The Math Conspiracy
6 2017-09-22 by MrNeoson
There are fewer people in the deep state than in the public community, including in science. So how can the deep state remain having an upper hand?
True knowledge is power. False knowledge is detrimental. By tricking the public scientific community into adopting false theories, the deep state clandestine scientific community can retain their control and power.
This includes knowledge in mathematics. As an example of how the public scientific community has been tricked, let's examine the set of real numbers between 0.0 and 1.0 and call this set S. The claim is that the set S is uncountable.
We can construct a bijection from N to S with binary representation like this: n(x) = sum(2xsi), where xsi is the i:th binary digit of the real number x in S. The set S is therefore countable. Cantor's theorem is false and a conspiracy to mislead the public scientific community.
EDIT: To clarify, the value n(x) represents the natural number for x in S. And only bits that are 1 should be included, so n(x) = sum(xi2i ), [xi is x subscript i] and for example with x = 0.1001101...
Then n(x) = 20 + 23 + 24 + 26 + ...
A cop out claim is that real numbers can have an infinite number of decimals and that Cantor's theorem therefore is true, but at the same time a common definition of the set of real numbers uses Dedekind cuts, which only are gaps between subsets of the set of rational numbers R which doesn't prove uncountability. The number 1/3 for example has an infinite number of decimals, yet R has the same cardinality as N.
412 comments
1 Corpuscle 2017-09-22
Except, of course, for irrational numbers.
1 MrNeoson 2017-09-22
Including irrational numbers. The real number x in S has the binary form 0.x0 x1 x2 x3 ...
The bijection is made by taking the sum of 2xi for all positions i. Each distinct x, including the irrational numbers, will in this way be mapped to a corresponding natural number.
1 birdman5000 2017-09-22
yeah it's the same technique used to have bitmaskable enumerations (ie. giving an enumerated item twice the prior value so that you can combine and separate each item).
1 Prunestand 2017-09-22
Then give me a natural for pi.
1 Prunestand 2017-09-22
Then give me a natural for pi.
1 trjb 2017-09-22
That's not a cop out. Is it a cop out claim to say irrational numbers have an infinite number of decimals? Or are you not including them in the set of reals?
Regardless this is my favorite post on this sub ever.
1 MrNeoson 2017-09-22
Numbers in S having an infinite number of decimals is no proof that S is uncountable. Take the rational number 1/3 again, it has an infinite number of decimals. Irrational numbers are commonly defined as Dedekind cuts which are merely cuts between two subsets of the set of rational numbers. The number of possible Dedekind cuts doesn't make S uncountable.
1 Neuro_Skeptic 2017-09-22
That's incorrect, but even assuming it was true, what does this have to do with "the deep state"?
1 MrNeoson 2017-09-22
By keeping true knowledge to themselves and tricking the public community into defending false knowledge, the clandestine "black op" deep state scientific community can remain having an upper hand.
1 kono_hito_wa 2017-09-22
Given that you're trying to make people believe false knowledge, you must be the actual "black op" here.
1 MrNeoson 2017-09-22
I still believe that my proposal is true. The problem is that when mathematicians claim that real numbers can have an infinite number of decimals, I can't fit my model into their models.
1 Firzen_ 2017-09-22
The rationals already contain all numbers with a finite number of decimals.
If reals couldn't have an infinite decimal expansion what would be the point?
1 MrNeoson 2017-09-22
That's a good point. And when I looked up the definition of e and found sum(1/n!), that's a rational number! Because infinity is not a number that can be reached. But I understand that in mathematics iterating to, and including, infinity is used, and that's how e is said to be irrational.
Anyway, as a side note I found on Wikipedia: "Moreover, R has the same number of elements as the power set of N."
That's interesting. 2N can be mapped to N like this (me shooting from the hip here :D):
P = 2N
p = a unique natural number for the subsets in P
n(p) = 2p
Bijection! And therefore the set of real numbers R and the set of natural numbers N have the same cardinality.
1 Firzen_ 2017-09-22
No set can be mapped to its powerset. I wrote a proof for that down in this thread before...
I also proved before that the powerset of the naturals is isomorphic to R.
You are assuming what you want to show here. Why would there be a unique natural number for every subset in P? That's only the case if a bijection exists, so you are already assuming your conclusion.
1 MrNeoson 2017-09-22
I was thinking of the same principle as when the set of even numbers get the same cardinality as the set of natural numbers. That can be done with the mapping n(e) = 2e. In this way the set of natural numbers is "stretched" to fit the set of even numbers.
Similarly, the idea is that n(p) = 2p is a mapping that stretches the set of natural numbers enough to always allow the natural numbers to be mapped one-to-one with the natural numbers of p.
1 Firzen_ 2017-09-22
Your function has to map from natural numbers to sets of natural numbers or the other way around. How else can it be a bijection?
If p is a set then 2p maps to a set of sets if p is a natural number 2p is a natural number.
None of this makes any sense.
1 MrNeoson 2017-09-22
Take a small example like S={0,1,2} and P = 2S = {0,1,2,3,4,5,6,7}. (I have converted the subsets in P to numbers.) With finite sets like these there is of course no bijection. With infinite sets however those can be stretched.
n(p) = 2p
n(0) = 1
n(1) = 2
n(2) = 4
...
n(7) = 128
And for the inverse, take for example the last element in P which is 7 mapped to 128 which with log2(128) becomes 7 again.
1 Firzen_ 2017-09-22
So first, this isn't a bijection because it isn't surjective, you are missing every natural number that isn't a power of 2.
And more importantly
That is only possible if there is a bijection to the natural numbers or a subset of them. You are assuming your conclusion.
Here's a crazy idea. If you can turn the subsets into numbers, just map every subset to the number. That's exactly what the point of the bijection is.
1 MrNeoson 2017-09-22
Yes, I made a big blunder. Instead the numbers can be assigned like this:
S = {0,1,2}
T = {1,2,4} which is 2s for all elements s in S.
P = 2T = {{}, {1}, {2}, {4}, {1,2}, {1,4}, {2,4}, {1,2,4}}
V = {0, 1, 2, 4, 3, 5, 6, 7} which is the sum of the numbers in each set in P.
Then there is a bijection between V and the set of natural numbers N.
1 Firzen_ 2017-09-22
Yes and if now S has infinitely many elements then there are infinitely many subsets with an infinite number of elements and your ""bijection"" would map all of them to infinity thus not being a function since infinity isn't in N and even less injective.
2N and 3N and 4N and so on are all going to be mapped to infinity.
1 MrNeoson 2017-09-22
All values in V are natural numbers and all natural numbers always have a finite number of digits. This means that all elements in V belong to N, even when S is infinite (S=N).
1 Firzen_ 2017-09-22
So what is the value in V corresponding to 2N?
1 MrNeoson 2017-09-22
I'm not familiar with the notation 2N. You mean the set of even numbers?
1 Firzen_ 2017-09-22
Yes, the set of all even numbers. What number does your bijection map it to?
1 MrNeoson 2017-09-22
The subset/member p in P that represents 2N looks like this:
{1, 4, 16, 64, 256, ...}
And the value for p in V is: sum(4i )
1 Firzen_ 2017-09-22
No, what number in N corresponds to that.
1 MrNeoson 2017-09-22
Oh, ok then it's the inverse function which is the same, so the value in N is also sum(4i ).
1 Firzen_ 2017-09-22
What is that notation supposed to mean? That's not a number in N
1 MrNeoson 2017-09-22
The value sum(4i ) is a member of N. It's the sum of 4 to the power of i, where i is a natural number iteration i=0, i=1, i=2, i=3 and so on. And since i is a natural number the index variable i will always have a finite number of digits and hence never reach infinity.
1 Firzen_ 2017-09-22
That's just plain wrong.
1 MrNeoson 2017-09-22
Not if the notation n = sum(4i ) is taken as an atomic expression representing a natural number. For example m = n + 1 and m > n. Compare with the value Pi. What is the exact value of Pi? 3.1415926 is just an approximation, not the actual exact value of Pi. Even tiny errors, no matter how small, can still produce chaotic butterfly effects.
1 Firzen_ 2017-09-22
If it represents a natural number it's finite and you can write it down.
1 MrNeoson 2017-09-22
One trick is to convert it to a rational number: q = sum(4-i ), i.e. the exponent is negated. Then q = 1 + 1/4 + 1/16 +...
q = 1.333333333... https://www.wolframalpha.com/input/?i=sum+4%5E-i
1 Roxor99 2017-09-22
That would still only account for the subset of 2N that are set of the power of a member of N. Where would all the others sets map to in Q?
1 MrNeoson 2017-09-22
I posted a version with rational numbers here: https://www.reddit.com/r/conspiracy/comments/71p28c/the_math_conspiracy/dnfs8us/
The entire power set of N is mapped into Q (unless I have missed something of course).
1 Firzen_ 2017-09-22
There is no reason to believe that all of these sums converge to rational numbers.
1 MrNeoson 2017-09-22
The iteration to infinity is done with index variable i as natural numbers. So the sum always remains rational.
1 Firzen_ 2017-09-22
That is incorrect as many people have pointed out to you before.
By that logic any infinite sum is finite since every finite sum is finite.
1 MrNeoson 2017-09-22
In my mapping all sums converge because of the negative exponent in the series.
1 Firzen_ 2017-09-22
No, that makes them cauchy sequences. It doesn't mean they converge in Q because Q isn't complete.
1 MrNeoson 2017-09-22
That explanation is a bit above my head. Can you give an example where the sum doesn't converge?
1 Firzen_ 2017-09-22
Imagine adding up the numbers 1/n with a small change.
If what you've summed up so far squared is bigger than 2 you subtract the next number otherwise you add normally.
Since you are only adding rational numbers every partial sum is rational. But the limit is obviously sqrt (2), which isn't a rational number. So the limit doesn't exist in Q.
1 MrNeoson 2017-09-22
Ok, I need to show that all my sums result in rational numbers. I think that is the case, but I don't know how to check that by attempting a formal proof.
1 Firzen_ 2017-09-22
Protip they don't.
1 Friek555 2017-09-22
Okay, let's take 1/3 and calculate your function: 1/3=0.01010101... in binary. So n(1/3)=22+24+26+28, this clearly diverges. So your function n does not map to the natural numbers. And even if you extend the natural numbers to include infinity, you would still get n(1/3)=n(2/3)=infty, so n would not be a bijection because is wouldn't be injective.
1 MrNeoson 2017-09-22
I think it's possible to define an inverse function of n(x), showing that it's a bijection, but I'm unsure about how to do that while still using math with natural numbers.
1 FUZxxl 2017-09-22
So you do not have a bijection.
1 hitbacio 2017-09-22
Your function isn't even well defined, let alone a bijection. What natural number does your function map 1/3 to?
1 MrNeoson 2017-09-22
That's easy. The number 1/3 in binary form is: 0.0101010101...
So n(1/3) = sum(22i + 1 )
The inverse is:
s(n(1/3)) = 1/3 = sum(n_i / 22i + 1 )
Bijection!
1 hitbacio 2017-09-22
That isn't a valid natural number.
1 MrNeoson 2017-09-22
True, but the set of rational numbers Q has the same cardinality as the set of natural numbers N. So instead of mapping the power set of N to N, it may be better to map it to Q.
1 hitbacio 2017-09-22
So you admit your function isn't well defined? Great!
Now go and find this mapping to Q.
1 MrNeoson 2017-09-22
Here is the version with rational numbers:
S = {0,1,2}
T = {1, 1/2, 1/4} which is 2-s for all elements s in S.
P = 2T = {{}, {1}, {1/2}, {1/4}, {1, 1/2}, {1, 1/4}, {1/2, 1/4}, {1, 1/2, 1/4}}
V = {0, 1, 0.5, 0.25, 1.5, 1.25, 0.75, 1.75} which is the sums of the numbers in each set in P.
Then there is an injection between V and the set of rational numbers Q.
For S = N, the set of natural numbers, there is through generalization of the above example an injection between V and Q. Therefore |2N| <= |Q|.
1 hitbacio 2017-09-22
Your map from P to V is not injective. For example the elements of p {1} and {1/2, 1/4, 1/8, ...} both map to the same element of V, namely 1.
1 MrNeoson 2017-09-22
No, the sum is always rational, so 0.99999... != 1.0. The iteration variable i is a natural number and can never reach infinity to make the sum equal to 1.
1 hitbacio 2017-09-22
1/2 + 1/4 + 1/8 + ... = 1 exactly. Do you dispute this?
1 MrNeoson 2017-09-22
I'm not using real numbers in the mapping. So in the mapping, 1/2 + 1/4 + 1/8 + ... = 0.99999... which is a rational number that is different the rational number 1.
1 Roxor99 2017-09-22
To which fraction does this 0.99999... correspond?
1 MrNeoson 2017-09-22
It's a well-defined rational number (I hope) but one has to write it as 0.9999... or as the sum(2-(i+1) ) I think.
1 Roxor99 2017-09-22
A rational number is ratio of two integers (natural numbers). I mean what two integers correspond to 0.99999...?
1 MrNeoson 2017-09-22
Yes, what I meant is that for a rational number in general it's impossible to determine the two integers for the rational number. Take the rational number closest to Pi (3.14159265...) for example. Really tricky (probably impossible) to find the two integers for that value.
1 Roxor99 2017-09-22
If you don't have the integers then how is it a rational number?
1 MrNeoson 2017-09-22
Rational numbers are always in the form a/b where a and b are integers, but to explicitly find what the values of a and b are is generally impossible or at least very difficult to do.
1 Roxor99 2017-09-22
No that's not hard at all. I can name any rational numbers and give you the integers associated with it.
1 MrNeoson 2017-09-22
So, for the rational number closest to Pi, can you find two integers that will define that number?
1 Roxor99 2017-09-22
No you can't, because that number doesn't exist.
1 MrNeoson 2017-09-22
Ok, so you mean 0.9999... doesn't exist either unless it's equal to 1?
1 Roxor99 2017-09-22
I think it's equal to 1 yes, but you said it was some other rational. So asked which one, but you couldn't name it.
1 MrNeoson 2017-09-22
I think it's valid to claim that 0.9999... != 1 when using rational numbers, but the value 0.9999... I can only define it as sum(2-(i+1) ). I can see a possible difficulty in that there is no end to how many nines can be added. It's always possible to add another 9.
1 Roxor99 2017-09-22
Well since that isn't a rational number your whole bijection falls apart.
1 MrNeoson 2017-09-22
Does it make a difference that I use injection instead of bijection? Maybe it's enough to show that the values in V "fit" into Q so to speak.
1 Roxor99 2017-09-22
If you make an injection between 2N and Q then you have shown that 2N is equal or smaller than Q. If you want to show that they are the same size then you need a bijection.
1 Prunestand 2017-09-22
There isn't a such rational number.
1 hitbacio 2017-09-22
1/2 + 1/4 + ... = 1 exactly. For a proof note that 1/2 + ... + 1/2n = 1 - 2-n, and 1 - 2-n converges to as n goes to infinity. Which part of the above do you think is wrong?
1 MrNeoson 2017-09-22
The value 1 - 2-n is always less that 1 when using rational numbers. You need to use real numbers to really squeeze down 2-n to zero.
1 hitbacio 2017-09-22
You don't need the real numbers to talk about limits, in the rational numbers 2-n converges to 0 using the standard topology.
1 MrNeoson 2017-09-22
Sounds like a convention. Are you sure that's a well-defined fact?
1 hitbacio 2017-09-22
Yes it is. Limits of rational numbers are defined as the limits in the usual topology. It's literally the definition of limits.
1 MrNeoson 2017-09-22
Then my definition is different. For example the rational number 1/n is never zero for any natural number n.
1 hitbacio 2017-09-22
Then state your definition for an infinite sum of rationals. Be very clear, no hand waving.
1 MrNeoson 2017-09-22
An infinite rational sum s = sum(q_i), where q_i are rational numbers indexed by natural number variable i.
1 hitbacio 2017-09-22
I don't know what sum(q_i) means when there are infinite q_i, please define it properly.
1 MrNeoson 2017-09-22
The value q_i is a member of Q. And i is a natural number variable iterating over all elements in N. So it's general definition. You can plug in all kinds of expressions in it as long as they match the definition.
1 hitbacio 2017-09-22
You still haven't defined it. At the basic level + only makes sense when dealing with summing two elements. It is easy to show that it makes sense to add up a finite number of elements (using induction), but you need to do a lot more for it to make sense for adding together infinitely many numbers.
1 MrNeoson 2017-09-22
Whoa, that sounds way too difficult for me to define. Heck, I don't even know how to define addition for a finite number of rational numbers.
1 hitbacio 2017-09-22
So once again you haven't defined a bijection, since your idea for a bijection relied on your own definition of infinite sums which you cannot give.
1 MrNeoson 2017-09-22
In my rational number mapping I only used injection instead of bijection since it's enough to show that all elements in V map to unique elements in Q and not necessarily all elements in Q mapping back to V as in a bijection. But yes, a formal definition of my sums seems too difficult for me to find at the moment.
1 hitbacio 2017-09-22
No matter how you define your sums you will never get injectivity. Have you seen cantors proof that a set is never in bijection with its power set? If not read it. If so where it the error in it?
1 MrNeoson 2017-09-22
I read about the proof for when X is countably infinite. They attempt to map N directly to P(N) and show that it fails. I use a different mapping into Q. It may be a difference since I "stretch" the numbers in the set representing P(N).
1 hitbacio 2017-09-22
The same proof holds for any set.
Since the rationals are in bijection with the naturals, any bijection P(N)->Q will give a bijection N->Q, so it's impossible.
1 MrNeoson 2017-09-22
If the proof is correct. My theory is that in Cantor's proof there is not enough stretching of the infinite sets, that the proof is too restrictive and that the infinite sets can be stretched to include their power sets.
1 hitbacio 2017-09-22
Where is the error in cantors proof? Can you point to the specific line he makes a mistake in?
1 MrNeoson 2017-09-22
From the proof: "Given such a pairing, some natural numbers are paired with subsets that contain the very same number."
Is that really true? Isn't it possible to construct such pairing so that no natural number is paired with a subset containing that number?
1 hitbacio 2017-09-22
Read it as some number may be paired with ...
Poor wording, but the it still works. It's just that the set of selfish numbers could be empty, which isn't a problem at all.
1 MrNeoson 2017-09-22
Ok, but here is another problem: "Let D be the set of all non-selfish natural numbers. By definition, the power set 𝒫(ℕ) contains all sets of natural numbers, and so it contains this set D as an element. If the mapping is bijective, D must be paired off with some natural number, say d."
It's possible to construct a pairing with no non-selfish numbers: n <-> {n, ...} and then D is the empty set and there is no number d.
1 hitbacio 2017-09-22
The empty set is an element of P(N). Indeed, the empty set is a subset of N.
1 MrNeoson 2017-09-22
Sure, but can you find any natural number d in the empty set?
1 hitbacio 2017-09-22
d is the number which is paired to the set of non-selfish numbers, which means that d is paired to the empty set. Since d is not in the empty set it means that it is a non-selfish number. But the set of non-selfish number sis empty, so cannot contain d. Contradiction.
1 MrNeoson 2017-09-22
Use the same proof for M = N u {} and pair the empty set in M with the empty set in P(M). And make all other other pairs n <-> {n, ...}.
Then D is the empty set and there is no number d, so by that proof |M| = |P(M)|. (If the proof is valid at all in that case since there is no number d.) And the claim is that the proof is without loss of generality.
1 hitbacio 2017-09-22
All you have showed there is that if you change the premise then you cannot use the exact same argument. Note that you haven't shown that |M|=|P(M)|, failing to derive a contradiction does not refute the premise.
What you've basically said here is that there is no flaw in the argument, because to find a flaw you have to change the argument itself.
1 MrNeoson 2017-09-22
Seems puzzling though. But I'm no expert. And also, I think I forgot to pair the {{}} in P(M).
1 hitbacio 2017-09-22
Not puzzling in the slightest that changing the proof makes it fail. In fact it's exactly what I would expect.
1 MrNeoson 2017-09-22
I can make a proof that contradicts Cantor's:
N = {0,1,2, ...} is the set of natural numbers.
T = {1,2,4, ...} which is 2n for all elements n in N.
P = 2T = {{}, {1}, {2}, {4}, {1,2}, {1,4}, {2,4}, {1,2,4}, ...}
V = {0, 1, 2, 4, 3, 5, 6, 7, ...} which is the sums of the numbers in each set in P.
N trivially injects into V. And if the mapping N to V in addition to being injective also is surjective then there is a bijection between N and V.
Claim the opposite, that the map N to V is non-surjective. Then there exists an element in V that is not mapped from N to V. This means that there is a number in V that is not a natural number. But by definition of V it is recognized that all elements in V are natural numbers. Therefore the claim is false and by proof by contradiction, the map N to V is bijective.
|V| = |P(N)| since V has the same number of elements as P and P is the power set of T and T has the same number of elements as N.
And because of the bijection N to V, |N| = |P(N)| (the cardinality of the set of natural numbers N equals the cardinality of the power set of N).
Q.E.D.
1 Firzen_ 2017-09-22
P and V do not have the same cardinality because you are mapping all infinite sets in O to infinity.
How many times does that have to be said?
1 MrNeoson 2017-09-22
Yes, I forgot about the infinite subsets. Tricky to deal with infinities. I can try the rational version again, with some general version of:
Lemma: The rational number 0.999... is not equal to 1.
Proof (loosely): Assume that 0.999... = 1 and then there exists an infinite decreasing sequence of natural numbers. That is false so by proof by contradiction 0.999... != 1.
1 Firzen_ 2017-09-22
Your proof doesn't really make any sense to me. Why would 0.999...=1 imply that there is an infinite decreasing sequence of natural numbers?
I'm assuming that in your understanding 0.999... is supposed to be the closest number to 1.
But obviously that doesn't exist, since (0.999...+1)/2 would be even closer still to 1.
In that case you might say that it's 0.999... again. Then let's say x=0.999... has the property that (x+1)/2=1. So let's see what x is, shall we?
(x+1)/2=1
x+1=2
x=1 Oh woops, something must have gone wrong, or 0.999... was 1 all along.
1 MrNeoson 2017-09-22
Because without an infinite decreasing sequence of natural numbers it's never possible to get from 0.999... to 1. And since there is no such sequence 0.999... != 1.
True, but I think sum(s-(i+1) ) still is a well-defined number 0.999...
It doesn't.
1 Firzen_ 2017-09-22
You are asserting that, but as far as I can tell there is no good reason at all to believe so.
Sure, it's also 1.
Yeah, I corrected it to (x+1)/2=x, my mistake.
1 MrNeoson 2017-09-22
Then, according to standard math, how does the rational number 0.999... become equal to 1? Is it just some convention or definition out of the blue? Does the claim have any solid mathematical foundation?
1 Firzen_ 2017-09-22
It doesn't become equal to 1. It is equal to one. Numbers don't change.
If you write 0.999... down as a series, you can check if the series converges and what value it converges to.
So let's use your sum definition for 0.999... for that.
x = sum(2-(i+1) ) = 1/2+1/4+1/8+...
2x = 2*(1/2) + 2*(1/4) + 2*(1/8) +...
2x = 1 + 1/2 + 1/4 + 1/8 + ... =1+x Because the bit after 1 + is exactly the same as x
2x=x+1
x=1
1 MrNeoson 2017-09-22
Not exactly. You have shifted the series one position.
1 Firzen_ 2017-09-22
You have invoked Hilberts Hotel yourself many times.
The stuff after the 1 is exactly the same as before. Nothing is missing ""at the end"" because there is no end.
1 MrNeoson 2017-09-22
I still think there is a problem with shifting series like that, but I have no proof yet. And it seems that there will be a problem with keeping Q a set if some elements become fused together like that. But that's just a guess.
1 Firzen_ 2017-09-22
The elements aren't ""fused"" together.
There are just different ways to write the same number,even though there is only one element in Q that corresponds to that.
0.999... = 1 = 2/2 = 2-1
And no there isn't a problem. There is no element missing. The ""shifted"" series is exactly the same after the "1+" because there is no gap and no element that is missing.
1 MrNeoson 2017-09-22
Then is the set V I defined actually the set of real numbers R?! Because the numbers in V can have an infinite number of decimals and include all combinations (because of the power set construction):
N = {0, 1, 2, ...} is the set of natural numbers.
T = {1, 1/2, 1/4, ...} which is 2-n for all elements n in N.
P = 2T = {{}, {1}, {1/2}, {1/4}, {1, 1/2}, {1, 1/4}, {1/2, 1/4}, {1, 1/2, 1/4}, ...}
R = {0, 1, 0.5, 0.25, 1.5, 1.25, 0.75, 1.75, ...} which is the sums of the numbers in each set in P.
1 Firzen_ 2017-09-22
No, it's not R, but it's the Interval [0,2] in R.
Congratulations, you've finally realized what people have been telling you for about 3 days now, the powerset of N is bijective to R.
1 MrNeoson 2017-09-22
Lol, I edited my comment because I had forgotten that it was only positive numbers, but yes it will be hard to produce numbers larger than 2 with my definition. :)
Here is a proof that |R| = |N|:
There can at most be only one Dedekind cut associated with each element in Q. Therefore R = Q u {cuts} has the same cardinality as the set of natural numbers N.
1 Firzen_ 2017-09-22
This again? I have discussed that nonsense with you before.
You are asserting again that there are only as many Dedekind cuts as there are elements in Q. That isn't correct and I've tried to explain to you why at length before, so I won't indulge that again.
1 MrNeoson 2017-09-22
Ok, but my interval [0,2] in R might be useful because it's a cleaner definition than Dedekind cuts. And make the interval [0, 1] instead and combine it with the set of integers to define the complete set R. Or has this already done? (I guess so, but just in case.)
1 Firzen_ 2017-09-22
You can not define a function into a set that doesn't exist yet.
You can't define R by having a function that maps to R, because that doesn't exist before being defined.
That's why the construction of the reals usually uses Dedekind cuts or equivalence classes of Cauchy sequences in Q, neither of which you seem to have even the tiniest amount of grasp on.
How about you spend some time reading up on this stuff before claiming to have overthrown well established knowledge?
How arrogant do you have to be, to think that for hundreds of years everyone that was presented this and concluded it made sense is wrong and that you, without even understanding basic concepts involved like what a set or a function is, have found the flaw in it that will overthrow mathematics as we know it?
There is no subjectivity in math, things are proven logically. If something is proven to be true, it will never stop being true with new knowledge being discovered or us achieving deeper insights into the universe or a regime change or whatever.
1 MrNeoson 2017-09-22
The set V = {0, 1, 0.5, 0.25, 1.5, 1.25, 0.75, 1.75, ...} doesn't map to R. It defines the interval [0, 2] in R, without R existing beforehand.
1 Firzen_ 2017-09-22
No, it doesn't. How can sqrt(2) be in that set without being defined? It doesn't define anything. A function is defined between two sets. It can't define one of the two sets.
Seriously dude, you don't even understand how functions work, MAYBE take a step back to at least learn what the terms you are using actually mean in mathematics.
1 MrNeoson 2017-09-22
I don't see why you need to define functions along with defining R. Surely it's possible to first define set R, and then after that define functions such as f:R->R.
1 Firzen_ 2017-09-22
Yes, that's not just possible, that's necessary.
But you can't define R with a function, because before being defined R doesn't exist.
1 MrNeoson 2017-09-22
I construct V from Q. So no set R needs to exist beforehand.
1 Firzen_ 2017-09-22
You can not define a set from a function.
Is that really so difficult to grasp? You can't define V from Q via a function and neither can you define R from V or R from Q that way...
1 Prunestand 2017-09-22
No, you can't. You can't define a new set by a function before you actually have the set.
1 MrNeoson 2017-09-22
But I have the set Q which is already defined, along with addition and so on.
1 Prunestand 2017-09-22
But you can't define a function from or to the real numbers if you don't have real numbers.
1 MrNeoson 2017-09-22
But the sums in V are rational numbers, although some on infinite number of elements! And all combinations included, so even irrationals like Pi and e become rational sum limits in V.
1 Firzen_ 2017-09-22
No, they don't. The sums aren't real numbers and we've been over this repeatedly.
1 MrNeoson 2017-09-22
Ok, then use the set P instead, which contains the subsets without summation as a definition of [0,1] in R. And from that, construct the complete set R together with the set of integers, and after that define addition and so on for R. And then the summation can be made just to get the numeric representation of the elements.
1 Firzen_ 2017-09-22
Congratulations!
You've just proposed a worse version of the construction of the real numbers as equivalence classes of Cauchy sequences in Q.
1 MrNeoson 2017-09-22
I thought it was an interesting idea, but sure I don't know enough to make a formal definition of R.
1 Firzen_ 2017-09-22
Well, aren't we all lucky that despite that you know enough to prove things about them.
1 Prunestand 2017-09-22
How about you actually learn about the things you try to debunk before trying to debunk them?
1 Prunestand 2017-09-22
So that's just essentially the Cauchy construction except it won't work at all. And it still doesn't prove reals are countable.
1 Prunestand 2017-09-22
No, the rationals are closed under addition. Are you an engineer or something?
1 MrNeoson 2017-09-22
Yes, I made a comment about it here: https://www.reddit.com/r/conspiracy/comments/71p28c/the_math_conspiracy/dnjgwuh/
1 Prunestand 2017-09-22
Worst definition ever, it won't even work. And it still doesn't prove what you claim; that reals are countable.
1 Prunestand 2017-09-22
This is false. You cannot map the set of all Dedekind cuts to the set of rationals, in a bijective manner.
1 MrNeoson 2017-09-22
No bijection needed in this case. It's enough to show that |{cuts}| <= |Q|,
1 Firzen_ 2017-09-22
There is no surjection from Q to the cuts, so good luck with that.
1 Prunestand 2017-09-22
There's no such surjection either.
1 Prunestand 2017-09-22
Because 0.999.. is defined in terms of limits, and this limit is 1.
1 Prunestand 2017-09-22
That sum is still 1 though.
1 MrNeoson 2017-09-22
Here is a proof that |N| = |P(N)| without using infinite sums:
Construct pairs between N and P(N) with 0 <-> {}, and for all other n in N: n <-> {n, ...}.
This is valid since for each n in N there is always an element in P(n) different from the empty set that is a subset of N containing n.
(Similar construct in Cantor's proof: "Note that the set D may be empty. This would mean that every natural number x maps to a set of natural numbers that contains x.")
Q.E.D.
1 hitbacio 2017-09-22
In your mapping from P to V (adding up all the elements), what does the subset of T {1,2,4,8,...} get mapped to? Because the sum of infinite natural numbers is not a natural number. Your map isn't even well defined (yet again), let alone a bijection.
1 MrNeoson 2017-09-22
Yes, I forgot that the sums of the infinite subsets will diverge to infinity. I may try the rational version again, although then there are numbers that are not closed or what it's called, and I need to define 0.999... != 1 and similar "collapses".
1 hitbacio 2017-09-22
Feel free to keep trying, but cantors proof is not wrong you you will never get a valid proof.
1 Prunestand 2017-09-22
Again, you map more than one element to infinity. So no bijektion.
1 Prunestand 2017-09-22
Then please tell us about the error in the proof.
1 MrNeoson 2017-09-22
I think I will have to give up on that. But what about Cantor's diagonal argument instead?
"Cantor considered the set T of all infinite sequences of binary digits"
Infinite sequence of binary digits? How could Cantor define such sequence?
1 Firzen_ 2017-09-22
Those are just the binary representation of the reals in the interval [0,1]
1 MrNeoson 2017-09-22
But for example:
x = sum(9*10-n)
y = sum(8*10-n + 10-(n-1)) - 19
x = 1
y = 1
Yet the decimal expansions differ:
x = 0.99999...)
y = 0.99998...))-19)
So those two binary sequences become "fused" together as the same element with the value 1 in the set of real numbers R.
1 Firzen_ 2017-09-22
1 MrNeoson 2017-09-22
A similar binary expansion can be made. The point is that many binary sequences like that become fused together in R. And Cantor can't use infinite induction in his diagonal proof.
1 Firzen_ 2017-09-22
What are you talking about, what do you even mean by fuse? There are only ever two infinite binary sequences that identify the same number.
One with a 0 followed by infinitely many 1s and a 1 followed by infinitely many 0s. Those are the only two sequences that will map to the same value.
And because those two always exist (except for 0) and are just two different respresentations of the same number you can just specify which of the two representations you want to pick.
1 Prunestand 2017-09-22
What do you mean by "fused"? A real number can at most have two different decimal expansions.
1 Prunestand 2017-09-22
It's just the decimal expansion in base two. Actually, you have to forbid decimal expansions ending in only ones because technical reasons. Otherwise you won't have unique decimal expansions.
1 Prunestand 2017-09-22
You can't even define addition for rationals, yet you claim that an infinite addition of rationals will give you a rational?
1 Prunestand 2017-09-22
But i becomes unbounded. How do you define the sum when adding infinitely many rationals?
1 MrNeoson 2017-09-22
Good point. With for all i in N the iteration never stops. So the sum can't be a rational value because the sum is never completed. Ok, scrap my idea about that kind of sum.
1 Prunestand 2017-09-22
Actually we can define it in terms of limits.
1 MrNeoson 2017-09-22
Yes, but I meant that the sum would make it so that 0.999... != 1 and the other cases like that.
1 Firzen_ 2017-09-22
0.999... is equal to 1.
1 Prunestand 2017-09-22
But 0.999... is defined in terms of a limit, and this limit is indeed 1. So 0.999... = 1.
1 Prunestand 2017-09-22
But i becomes unbounded. How do you define the sum when adding infinitely many rationals?
1 Prunestand 2017-09-22
No one ever claimed that. However, the limit as n approaches infinity will be zero. And you don't need reals for that.
1 Prunestand 2017-09-22
No, you don't need reals. The limit will be 1, even if you only consider rationals.
1 Prunestand 2017-09-22
But 0.999... is exactly 1 and considered as a limit.
1 Prunestand 2017-09-22
That's not a natural number.
1 MrNeoson 2017-09-22
True, the inverse uses rational numbers, so that's invalid if only natural numbers can be used for the inverse function.
1 Prunestand 2017-09-22
No, you it isn't still a bijection. You still map all irrationals to one element.
1 Prunestand 2017-09-22
That's not a natural number.
1 Prunestand 2017-09-22
That's not a natural number.
1 Prunestand 2017-09-22
That's not a natural number.
1 EmperorZelos 2017-09-22
Is not a natural number so it is not even a function.
1 Friek555 2017-09-22
No, it is impossible because 1/3 and 2/3 both map to infinity. Thus n is not injective, by the definition of injectivitiy. Any bijection is surjective and injective, so n is not bijective.
1 killerjavi98 2017-09-22
Can you provide some links of this you caught my interest.
1 MrNeoson 2017-09-22
Controversy over Cantor's theory -- https://en.wikipedia.org/wiki/Controversy_over_Cantor%27s_theory
Since that's a link to Wikipedia, no conspiracy theories there. However, the key problem with Cantor's theorem is that it compares numbers with equal number of digits, such as: https://en.wikipedia.org/wiki/Cantor%27s_diagonal_argument
In truth there are an infinite number of possible extensions of number of digits, so Cantor makes a mistake by comparing numbers of increasing yet equal number of digits. Because compare with the set of even numbers E which has the same (infinite) cardinality (size) as the set of natural numbers N. This can be shown by the mapping e(n) = 2n. In this case N is "stretched" to fit E, yet in Cantor's diagonal argument that kind of stretching has been limited.
1 EmperorZelos 2017-09-22
It hasn't, what cantor showed there is a quick and intuitively easy way that reals have higher cardinallity. The proper proof is more set theoretical.
1 DrDerpinheimer 2017-09-22
So an 1800s mathematician conspired to destroy mathematics. Meanwhile, in one line, you completely disproved him.
If you were confident in this, then you'd write a paper. Not post here.
1 MrNeoson 2017-09-22
Many math experts no doubt already know about this problem with Cantor's theorem and the set of real numbers. But for a century they have had to defend and whitewash it in order to protect their credibility. So any attempt to publish something like this in a paper will most likely be rejected by the public mathematical community.
1 DrDerpinheimer 2017-09-22
I see that there is debate over it, but it doesn't appear to be a meaningful one.
Just post on math.stackexchange.com and see what people have to say.
1 MrNeoson 2017-09-22
I have to make the presentation more formal. One idea I came to think of is to look at all the Dedekind cuts, and at most there can be only one cut between each rational number pair with minimal difference between the numbers. And then the rational numbers can be mapped to the set of even numbers and the cuts (which include the irrational numbers) can be mapped to the set of odd numbers, i.e. the set of real numbers R then is shown to have the same cardinality as the set of natural numbers, which means R is countable.
1 DrDerpinheimer 2017-09-22
I'd love to discuss it with you, but I don't really understand deep maths like this.
1 MrNeoson 2017-09-22
It's fairly simple math actually. What the experts do is try to obscure embarrassing past errors like that with all kinds of extremely complicated mathematical detours to distract from having to admit it's a collective mistake. They desperately need to save face to uphold their seeming credibility in the eyes of the laypeople, which serves the deep state scientific community well since it hampers progress in the public scientific community.
1 StickLick 2017-09-22
Next time you struggle on your homework you should ask for clarification not assume there's a big conspiracy to keep math hard.
1 TomSwirly 2017-09-22
HAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHA!
Refutation is here.
1 EmperorZelos 2017-09-22
Ooorrr again, it can be that you are ignorant and don't see the blantant error in your shit. It is quite trivial to show that R is uncountable, cantors is one of them with the diagonal arguement which shows that no matter what supposed list you have, he can find elements you missed.
Other is cantors theorem which is more general that shows that there is no surjection from S to P(S), and hten showing |P(N)|=|R|, both not difficult.
1 shaggorama 2017-09-22
Knock yourself out: neither does OP.
1 eario 2017-09-22
There is no such thing as "a rational number pair with minimal difference between the numbers". If you give me a pair of distinct rational numbers a and b, then I can find a rational number c between them, so that the difference between a and c and the difference between c and b is smaller than the difference between a and b (For example c=(a+b)/2 has this property). So what do you mean when you talk about a "rational number pair with minimal distance between the numbers".
If you have two distinct rational numbers, then there are infinitely many real numbers between them. And similarly if you have two distinct real numbers then there are infinitely many rational numbers between them. So I don´t see how "mapping the rationals to the even numbers and mapping the irrationals to the odd numbers" is supposed to work.
1 MrNeoson 2017-09-22
One way of describing it is to map the rational numbers to the natural numbers. And then it's easy to see that the minimum difference between a pair of natural numbers is 1 (the pair here is not allowed to contain the same number).
1 eario 2017-09-22
That doesn't work. There are bijection between the rational numbers and the natural numbers, but they are not monotonous.
As an example let´s just take a list of all rational numbers from a random website.
https://proofwiki.org/wiki/Rational_Numbers_are_Countably_Infinite#Proof_1
In this list the first entry is 0/1. The second entry is 1/1. As far as I understand you, you suggest that in this situation 0/1 and 1/1 have minimum distance. But 1/2 is inbetween them, and has smaller distance to both of them, so the distance between is not minimal. If you want your suggestion to work, then you need to find a list of all rational numbers where the entries are always getting bigger and never smaller, and that doesn´t exist.
1 TomSwirly 2017-09-22
And why is this an issue?
1 StickLick 2017-09-22
Wi th logic like that I'm surprised you don't post on holofractal.
1 iam_we 2017-09-22
Is that supposed to be an insult?
1 StickLick 2017-09-22
Yes that entire cult is a joke.
1 Neuro_Skeptic 2017-09-22
"I'm smarter than most people. Some people are as smart as me, but I'm braver than them." - you
1 TomSwirly 2017-09-22
Mathematician here.
HAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAHAH!
Er, sorry, but this is SO dumb.
Refutation at the top level.
1 TheDankestGrowaway 2017-09-22
I'm sorry, but any mathematician that was capable of completely rewriting portions of mathematics as we know it would never have to worry about their credibility. The problem is in the capability to do so. You're more than welcome to try, but literally everything you've mentioned here is so ill reasoned, I'm not sure you'll get very far.
1 EmperorZelos 2017-09-22
OOorrr a more possible explination is that you are too stupid to understand basic anything.
1 spacelord_rasputin 2017-09-22
I'm very confused by this, would you mind clarifying some things for me? You say n(x) = sum(2xsi ) where xsi is the ith bit of a real number in [0,1]. Since xsi is always 0 or 1, 2xsi is always 1 or 2 and n(x) diverges for all x. Did you mean something else?
1 MrNeoson 2017-09-22
The sum will diverge because it represents the natural numbers going to infinity. But ok, it's cleaner if the sum is only for bits that are 1. Take for example x = 0.1001101...
Then n(x) = 20 + 23 + 24 + 26 ...
1 spacelord_rasputin 2017-09-22
Oh, I see what you mean now. So to be more precise, n(x) = sum(2xsi*i ). However I must still take issue with this. Since n(x) diverges for all x in [0,1], as I see it, n(x) does not form a bijection between N and R as you claim, it maps all of R to infinity. N is infinite, but infinity is not in R.
1 MrNeoson 2017-09-22
Compare with the cardinality between the set of even numbers E {0, 2, 4, 6, ...} and the set of natural numbers N {1, 2, 3, 4, 5, ...} they have the same cardinality (size). A bijection can be made with e(n) = 2n. Do you have issue with that too? The set N is infinite, yes, but all natural numbers (the elements in N) all have a finite number of digits.
1 spacelord_rasputin 2017-09-22
I do not have a problem with that. I have a problem with n(x) being many-to-one by virtue of mapping all irrationals to infinity. Bijections are by definition one-to-one, so n(x) is not a bijection.
1 MrNeoson 2017-09-22
You mean irrational numbers have an infinite number of decimals? Compare with the rational number 1/3 which has an infinite number of decimals, yet the cardinality of R, the set of rational numbers, is the same as the cardinality of the set of natural numbers N.
1 spacelord_rasputin 2017-09-22
Yes, any irrational number will have infinitely many non-zero digits in any base, since irrationals have terminating expansions by definition. But as your example shows, we don't even need to consider the irrationals to show that n(x) is not a bijection between N and R. Any rational with a denominator that is not a power of 2 will have infinitely many 1 bits in its expansion, and thus map to infinity, which again shows that n(x) is many to one. e.g. n(1/3) and n(1/5) both map to infinity.
1 MrNeoson 2017-09-22
When defining the irrational numbers as Dedekind cuts, then as I wrote in another comment: at most there can be only one cut between each rational number pair with minimal difference between the numbers. And then the rational numbers can be mapped to the set of even numbers and the cuts (which include the irrational numbers) can be mapped to the set of odd numbers, i.e. the set of real numbers R then is shown to have the same cardinality as the set of natural numbers, which means R is countable.
1 spacelord_rasputin 2017-09-22
I'm afraid my expertise does not extend to Dedekind cuts. But I would imagine that someone who is versed enough to be familiar with Dedekind cuts would be capable of addressing my simple argument on the lower terms I have employed. This strikes me as similar to invoking calculus in an effort to prove that 1+1=2.
1 MrNeoson 2017-09-22
But even without Dedekind cuts the number 1/3 has the same number of decimals as an irrational number. In binary form 1/3 = .01010101...
And n(1/3) = 21 + 23 + 25 + ...
Or are you saying that an irrational number has more decimals than the rational number 1/3?
1 spacelord_rasputin 2017-09-22
True that 1/3 has infinitely many 1 bits in its binary expansion, as do all irrationals. But the crux of my argument is that all reals with infinitely many 1 bits in their binary expansions, whether rational or irrational, will map to infinity given your n(x). If more than one x maps to infinity, then n(x) is many to one, and therefore cannot be a bijection.
1 MrNeoson 2017-09-22
That's the conspiracy! Real numbers don't have an infinite number of decimals. And since the set of real numbers R can be defined using Dedekind cuts, and the number of those cuts is not larger than the number of rational numbers, R is countable. So the public scientific community has to whitewash and cover up that early deliberate mistake.
1 spacelord_rasputin 2017-09-22
I guess I'm confused again. Saying that all reals terminate is equivalent to saying that all reals are rational. Yet you mentioned Dedekind cuts, so you must believe irrationals exist. Of course R is countable if all reals are rational.
1 MrNeoson 2017-09-22
Not terminate, just as natural numbers there is no end to how many digits they can contain yet the number of digits is always finite! The set N itself is infinite, but:
"By induction, we conclude that S=NS=N. That is, every natural number has only finitely many digits when written in base 10 with no leading 0s." -- https://math.stackexchange.com/questions/58085/a-number-with-an-infinite-number-of-digits-is-a-natural-number
1 spacelord_rasputin 2017-09-22
But irrational numbers do have an infinite number of non-zero digits in their expansions:
>It can be shown that irrational numbers, when expressed in a positional numeral system (e.g. as decimal numbers, or with any other natural basis), do not terminate, nor do they repeat, i.e., do not contain a subsequence of digits, the repetition of which makes up the tail of the representation. For example, the decimal representation of the number π starts with 3.14159265358979, but no finite number of digits can represent π exactly, nor does it repeat.
1 MrNeoson 2017-09-22
"do not terminate" is not the same as infinite length. The size of the set of natural numbers N is the infinite ordinal number ω. But ω doesn't appear in the set N itself. That would be to mix apples and oranges.
1 almightySapling 2017-09-22
In this context, yes it is.
Well, no, ordinals don't denote size, they denote order type. The size of the set N is aleph_one. This happens to be the same set as ω so you aren't too far off here.
True, but so what? Nobody is claiming anything like this happens with irrational numbers. Each real number (rational or irrational) has infinitely many digits to the right of the decimal point (one digit for each natural number). Nobody is saying there's an "ω-th digit".
1 MrNeoson 2017-09-22
You agree at least I take it that infinite ordinal numbers are not natural numbers, yet the claim is that real numbers can have an infinite number of decimals. That's inconsistent. That's mixing apples and oranges.
1 almightySapling 2017-09-22
Yes
Why is that inconsistent? What does the number of digits in a real number have anything to do with whether infinite ordinals are natural numbers?
1 MrNeoson 2017-09-22
Because by claiming that real numbers can have an infinite number of decimals, it's impossible to form a set of real numbers. For example are 0.999... and 1.0 the same element in R?
1 Firzen_ 2017-09-22
Yes they are the same element.
1 MrNeoson 2017-09-22
See my reply about the continuum conspiracy.
1 almightySapling 2017-09-22
Wait, what? You are going to really need to elaborate on what you say here. Why can't I have a set of real numbers? Is [0,1] not a set? What does this have to do with the number of digits?
Yes, so?
1 MrNeoson 2017-09-22
The problem is the so-called continuum, another conspiracy to mislead the scientific community. There cannot be any continuum. Zeno's paradoxes show that.
1 Firzen_ 2017-09-22
If you think Zeno's paradoxes show anything, do you also think movement is impossible?
1 MrNeoson 2017-09-22
Movement is possible because in reality space is quantized, not a continuum.
1 almightySapling 2017-09-22
"I don't know enough to actually refute that, and I refuse to admit that I'm wrong, so I'll just toss out a non-sequitur"
Have a nice day dumbass.
1 MrNeoson 2017-09-22
Zeno's paradoxes work over Q, that I can believe, but not over R. That's the conspiracy.
1 almightySapling 2017-09-22
Zeno's paradoxes say the same things about Q and R. If you consider Zeno's paradox to prove any statement about one of these things, it proves the same thing about the other.
1 Prunestand 2017-09-22
Yes, they do.
1 MrNeoson 2017-09-22
See my other comment.
1 Firzen_ 2017-09-22
What makes you think that there are only countably many dedekind cuts?
1 MrNeoson 2017-09-22
My idea is that there can at most be only one cut between each rational number. And the set of rational numbers Q has the same cardinality (size) as the set of natural numbers N. And since the set of even numbers E also has the same cardinality as N, all the rational numbers can be mapped to E and all the cuts can be mapped to the set of odd numbers O. And E union O = N, i.e. the set of real numbers R is countable.
1 Firzen_ 2017-09-22
The set of rational numbers is dense in R, but does not have the same cardinality.
I get that that is counter intuitive. Nevertheless it is true.
If they had the same cardinality you'd be able to list the real numbers in a specific order, thus creating a bijection N <=> R, which Cantor has proved impossible quite conclusively.
As for some of the other things I read in this chat. Are you saying that no irrational numbers exist, or are you saying that they have terminating representations?
1 MrNeoson 2017-09-22
My claim is that Cantor's theorem is false. Because I showed how the set of natural numbers can be mapped into the real numbers between 0.0 and 1.0.
1 Firzen_ 2017-09-22
It'd be great if you did, alas you didn't.
The reason your function isn't a bijection has been pointed out to you repeatedly I think.
And Cantors theorem is something else than the Cantor diagonalization argument. It works just as well though.
We can pretty easily show that the powerset of the natural numbers is bijective to the real numbers in the interval [0,1].
The powerset is the set of all subsets of N.
Now every subset S of N corresponds to the number that has a 1 in it's n-th binary place exactly if S contains the n-th number in N.
So N maps to 1, the empty set maps to 0 and {1,2,3} maps to 0.111.
This is pretty clearly a bijection, so we know that P(n) has the same cardinality as [0,1].
Now Cantors theorem states that the cardinality of any set is strictly smaller than that of its powerset.
So since R and P(n) have the same cardinality N has to have smaller cardinality than R.
The proof for that is one I actually prefer to the diagonalization argument:
Assume a bijection f:N->P(N) exists, then it is also surjective.
Consider the set B that contains all numbers n that are mapped to a set that doesn't contain them. So B = {n in N | n not in f(n)}.
Since f is surjective it has to map to every subset of N, which contains B, so there is some x with f(x) = B. Now if f(x)=B, then B can not contain x, but if B doesn't contain x, then it should contain x.
This is clearly a contradiction, so such a bijection can not exist.
Therefore the cardinality of N is strictly smaller than that of P(n) and also R.
1 MrNeoson 2017-09-22
I claim that Cantor's theorem is false and that the cardinality of the power set of N is the same as the cardinality of N. Just look at Hilbert's hotel infinity.
1 Firzen_ 2017-09-22
I literally wrote the proof down for you.
If you claim that it's false disprove it, don't just declare it and invoke a completely unrelated thing.
The three steps in Hilberts Hotel prove that:
1. N is isomorphic to N+1
2. N is isomorphic to 2N
3. N is isomorphic to NxN where x is the cartesian product.
None of that has anything to do with the powerset.
1 MrNeoson 2017-09-22
But isn't N also isomorphic to 2N. I remember that Hilbert's Hotel Infinity even uses primes and things like that. Infinities within infinities within infinities.
1 Firzen_ 2017-09-22
No N isn't isomorphic to 2N because that would be the powerset and I proved literally 4 comments up this chain that they can not be isomorphic.
Hilberts Hotels last stage is having infinitely many busses with infinitely many guests. So for every number in N there is a bus containing one guest for every number in N.
That makes it NxN not 2N.
1 MrNeoson 2017-09-22
I don't get it. For example a set S={1,2,3} has a power set with 8 subsets. There is a bijection between 2S and the set {1,2,3,4,5,6,7,8}.
Isn't it possible to generalize that to the whole set of natural numbers? I didn't understand your proof earlier. Can you give a simpler explanation?
1 Firzen_ 2017-09-22
Yes there is a bijection between those two sets because they have the same number of elements.
I'll try to explain it more simply, but first answer this question:
Do you think that there can ever be a bijection between S and 2S ?
1 MrNeoson 2017-09-22
1 Firzen_ 2017-09-22
Your mapping is not a bijection and people have pointed out the reason for that repeatedly, so I'm not even going to engage that.
So let's take a look at 2N . It's the set of all subsets of N. Any subset of N either contains or doesn't contain the n-th natural number. So for example the set that contains all of them is N and the set that contains none of them is the empty set.
Now it's easy to see that this is bijective to [0,1].
Let's say that for a set A, A_n is 0 if A doesn't contain n and is 1 if it does.
Then f(A) = Sum A_n*2-n is obviously a bijection between P(A) and [0,1].
Are you with me so far?
1 MrNeoson 2017-09-22
Sorry, that's too complicated for me. And my claim is still that my mapping is a bijection:
n(x) = sum(x_i(2i )) s(n) = sum(n_i / (2i ))
s(n(x)) = x
1 Firzen_ 2017-09-22
As a variety of other people have already pointed out to you n(x) isn't an injection not even from the rationals, since it doesn't even map 1/3 or 2/3 and if it did it would map them to infinity, which isn't part of the natural numbers, hence it doesn't even map them at all.
1 MrNeoson 2017-09-22
That's only because you insist that real numbers can have an infinite number of decimals. That's philosophically speaking the same as claiming that a natural number can have an infinite number of digits (which it can't).
1 Firzen_ 2017-09-22
You say I insist, but there are obviously even rational numbers with infinite decimal expansions. Like 1/3.
The decimal representation of a number isn't the number, it's a representation. 0.25 = 1/4 =2/8. You can have lots of representations of the same number.
And yes, a real number can have infinitely many digits, because it is still bounded. Almost all real numbers between 0 and 1 have an infinite decimal representation. But none of them are bigger than 1. If natural numbers had infinitely many digits however then they would become infinitely large and not even be numbers anymore.
1 Prunestand 2017-09-22
The problem is that your supposed bijection is not a bijection. For starters, you would map all irrationals to infinity. The same is true for rationals with an infinite decimal representation. What you have shown is that a subset of the rationals, rationals p/q where q contain all the prime factors of 10, is countable.
1 MrNeoson 2017-09-22
I see in another comment that you claim that real numbers can have an infinite number of decimals. That's the mistake. That's the conspiracy. With unending number (not the same as infinite) of decimals there is a bijection.
As I wrote in another comment: When defining the real numbers using Dedekind cuts then at most there can be only one cut between each rational number pair with minimal difference between the numbers. And then the rational numbers can be mapped to the set of even numbers and the cuts (which include the irrational numbers) can be mapped to the set of odd numbers, i.e. the set of real numbers R then is shown to have the same cardinality as the set of natural numbers, which means R is countable.
1 Prunestand 2017-09-22
But almost all reals have an non-terminating non-repeating decimal expansion. Hence, almost all reals would be mapped to infinity.
The set of all Dedekind cuts is not countable. Between any two rationals, you can always find uncountably many irrational numbers. You assumption is false.
1 MrNeoson 2017-09-22
Each cut only defines one unique number, and a pair of rationals with minimal difference are the end of A and the beginning of B:
"... that cut defines a unique irrational number which, loosely speaking, fills the "gap" between A and B. In other words, A contains every rational number less than the cut, and B contains every rational number greater than or equal to the cut." -- https://en.wikipedia.org/wiki/Dedekind_cut
1 Prunestand 2017-09-22
The difference is not well-defined, because the cut contains rationals "infinitely close", so to speak.
1 MrNeoson 2017-09-22
Ok, but that sounds shaky. It seems to me that the whole real number business has been messed up deliberately to mislead the public scientific community. A bit off topic, but still a math conspiracy, I linked to this in another post, and if you know a lot about math you might be interested (it's about Einstein's flawed math): http://www.gsjournal.net/old/weuro/anderton78.pdf
1 Prunestand 2017-09-22
We know perfectly fine what real numbers are.
1 TomSwirly 2017-09-22
You keep talking about this idea: "a pair of rationals with minimal difference".
There is no such thing. Pick an irrational number like the 1/sqrt(2) - or, honestly, any irrational you like - now, what exactly are these "pair of rationals with minimal difference"?
1 MrNeoson 2017-09-22
Take two rational numbers a and b, a!=b, and construct a pair (a, b) such that a < b, and for all rational numbers c, c =!a and c != b, c is either smaller than a or larger than b.
1 TomSwirly 2017-09-22
This is impossible to do. Given any such pair or rationals a and b, it is trivial to find a rational number c between those two
Prove me wrong - let's see you actually do this calculation for any irrational number of your choice.
1 MrNeoson 2017-09-22
The constraint is that c is either smaller than a or larger than b, so there is no c between a and b.
1 TomSwirly 2017-09-22
Now you are assuming what you are trying to prove. That's a real no-no!
Here's your statement:
Well, my claim is that this is impossible because I can always find many examples of
c
that breaks your rules. An easy example is the averagec = (a + b) / 2
, which is a rational number that's always between a and b.So I know that for any pair of numbers a and b you give me, there are some numbers c so such that a < c < b. So you cannot construct such a pair a, b.
QED. :-D
1 erosPhoenix 2017-09-22
For any two rational numbers a and b, a != b, a<b, it is always possible to construct a rational number c = (a+b)/2 that is greater than a and less than b. Thus, there cannot exist a "pair of rationals with minimal distance"
1 MrNeoson 2017-09-22
Ok, scrap the minimal distance idea. But are you willing to accept that there can at most be only one cut between each rational number?
1 erosPhoenix 2017-09-22
What do you mean by "each rational number"? You can't mean "each successive rational number", because without the concept of minimal distance pairs, there's no such thing as successive rational numbers. And you can't mean "at most one cut between any two rational numbers" either, because then for any two cuts, you could find a rational number greater than the upper cut and a rational number less than the lower cut.
If you mean to say "For any two cuts there exists a rational number between them", that that's just a restatement of the theorem that there exists at least one rational number between any two irrational numbers, and I don't see how that helps your proof.
1 MrNeoson 2017-09-22
Yes, I see now that successive rational numbers can be tricky. Instead look at the set of rational numbers Q with arbitrary ordering of its elements. And, belonging to each element in Q, there can at most be only one Dedekind cut.
1 qlikers 2017-09-22
Can you explain dedekinds cut to me?
1 MrNeoson 2017-09-22
If we start with the Wikipedia definition: "In mathematics, a Dedekind cut is а method of construction of the real numbers. It is a partition of the rational numbers into two non-empty sets A and B, such that all elements of A are less than all elements of B, and A contains no greatest element."
So the partition is always so that A contains the smaller numbers and B contains the larger numbers. How many different such partitions are possible? The answer is at most |Q|, i.e. the cardinality ("size") of the set of rational numbers. So again, the number of Dedekind cuts is at most one for each rational number.
1 Firzen_ 2017-09-22
No, the answer is at most |P(Q)| since both A and B are subsets of Q and not elements, as has been pointed out to you repeatedly.
1 MrNeoson 2017-09-22
No, because there is an ordering where A contains the smaller numbers and B the larger numbers. So it's simply a split of Q in two, not some power sets of Q.
1 Firzen_ 2017-09-22
You can't describe the split in two with a finite number of rational numbers, that's the whole point.
As an exercise for you, which rational number do you think splits the rationals in two around the square root of 2? I can easily define the two sets, but there is no closest rational to the square root of two from either side. So which rational number would identify that?
1 MrNeoson 2017-09-22
Still, there is a clearly defined and unique split between A and B. Take the split at the sqrt(2). It's only one unique split possible for sqrt(2).
1 Firzen_ 2017-09-22
Yes, for every real number there is exactly one split, that's why the dedekind cuts are used to define the reals. Not for every rational one. Otherwise some rational number could describe sqrt(2).
1 qlikers 2017-09-22
So you can dedekind cut the real numbers between A < 1 and B >= 1. And this is valid because A is less than all elements of B, and A doesn't have a largest element.
Because if I said .99 is the largest element, you could just tack on another .009 and get .999 which is larger.
And then you can do this for all rational numbers, |Q|?
And then you can do this for sqrt(2) so the sqrt(2) is rational.
1 MrNeoson 2017-09-22
It's true that in your example A has no largest rational number. However there is a clear split between which elements in Q belong to A and which belong to B. There is only one possible split.
1 qlikers 2017-09-22
I guess I'm confused on how to get from the construction step, to at most |Q|.
1 Firzen_ 2017-09-22
The square root of 2 isn't rational.
You don't get to at most |Q|. /u/MrNeoson doesn't know what he's talking about.
1 MrNeoson 2017-09-22
So, you believe there can be more Dedekind cuts than elements in Q? That's obviously false. A and B contain rational numbers, not subsets of Q. A subset of a rational number is not a rational number.
1 Firzen_ 2017-09-22
What do you think a subset is? What do you think A and B are?
1 MrNeoson 2017-09-22
The cut is defined by the numbers in A and B. There are no subsets in A or B. For example the subsets {1/2} and {1/2, 1/3} are not rational numbers.
1 Firzen_ 2017-09-22
A and B are subsets. The fact that you need subsets to define the cuts is the point.
1 MrNeoson 2017-09-22
Of course, but the elements in A and B are all rational numbers. And with the smaller numbers in A and the larger numbers in B. So you cannot get the combinatorial explosion you seem to want.
1 Firzen_ 2017-09-22
Your mistake is that you think there is a next rational number for any given number. There isn't.
Assume for some rational number x there was a next rational number y. Then (x+y)/2 would be in between them, so y can't be the next one.
You can't "walk" the rational numbers. There are more ways to split the rational numbers into two halves than there are rational numbers.
The real numbers are those splits. You are assuming the result you want by claiming that they can't be split in more ways than there are elements in Q. That doesn't prove anything, you are just asserting this over and over again.
I wish I could give you a more intuitive example to wrap your head around it, but there isn't one.
Many people in this thread have spent time to write down proofs to show you that you are wrong, but you just go: "Oh that's too hard for me, don't get it"
Meanwhile you claim to have disproven an accepted mathematical fact, without any proof and with a ""bijection"" that isn't even a function and even less bijective.
1 MrNeoson 2017-09-22
That seems false. But I give up now. I admit that I haven't grasped the cardinality of power sets yet. I will have to look into that.
1 Firzen_ 2017-09-22
I agree that it seems false. It's certainly unintuitive.
But there are many ways to prove it. I wrote down a proof for that in our conversation here.
Just, you know, turn down your arrogance a tad. Those are basic concepts that anyone with a higher math education knows and you think you are overthrowing established knowledge without fully grasping it.
1 Firzen_ 2017-09-22
Sure.
But A has to contain infinitely many elements to do that.
Of course there is only one possible split, because there is only one square root of 2. If there was more than one, Dedekind cuts would do a poor job of defining the reals.
But if picking an element from Q isn't enough to define where that split is, then why do you think that there can only be as many splits as elements in Q?
Think about this. For any two distinct elements from Q that you select, there are infinitely many elements of Q between them.
1 MrNeoson 2017-09-22
It's the split into A and B that defines the cut. And A union B = Q. And because of the ordering with the smaller numbers in A and the larger numbers in B, the number of possible cuts cannot exceed the number of elements in Q.
1 Firzen_ 2017-09-22
Again, there is no largest number in A and no smallest number in B, so even if it goes against your intuition you need more than just a finite amount of rational numbers to define where the cut is.
Your intuition is right for the finite case, but the finite case doesn't always carry over to the infinite case.
If you think it does then surely a powerset of a set S having 2|S| elements ought to convince you that no set can have the same cardinality as its power set, which is actually true even in the infinite case.
1 MrNeoson 2017-09-22
Who said it has to be a finite number of elements in A and B? I can split the set of natural numbers into one set of even numbers and one set of odd numbers. Both those subsets are infinite.
1 Firzen_ 2017-09-22
If a finite number of elements in A and B were sufficient there'd be a bijection to Q, that's why it's relevant that you need an infinite number of elements to define them.
What does splitting the naturals into odd and even have to do with anything? We aren't talking about the natural numbers.
1 MrNeoson 2017-09-22
Ok, I will stick to the rational numbers. Take A with numbers less than sqrt(2) and B with numbers equal or greater than sqrt(2).
Is the set S = A u B u {cut} countable? Yes! And then add another cut. And another cut, and so on. When does the set S become uncountable?
1 Firzen_ 2017-09-22
With the process you are describing it will never become uncountable and it will never become the set of real numbers.
If you think in any kind of process it won't get you anywhere. If you can add things step by step then you can number the steps and the result will necessarily be listable.
The real numbers are the set of ALL dedekind cuts in the rationals.
1 Prunestand 2017-09-22
It's not clear what you mean. You can find one unique Dedekind cut for each rational, yes.
1 MrNeoson 2017-09-22
My idea is that each rational number in Q can have at most one cut associated with it. And then the set S = Q u {cuts} still has the same cardinality as N.
1 Prunestand 2017-09-22
This is simply not true, since there are more cuts than rational numbers.
1 MrNeoson 2017-09-22
Then there are cuts between cuts. Aren't cuts only allowed between sets A and B, both containing only rational numbers?
1 Prunestand 2017-09-22
I'm not sure what you mean. A cut always contain rational numbers.
1 Firzen_ 2017-09-22
He wants to make a counting argument because of the total order of Q and all a in A being smaller than all b in B.
1 Prunestand 2017-09-22
But that doesn't work for irrationals.
1 Firzen_ 2017-09-22
I know that, but he thinks every cut is uniquely determined by the rational ""in the middle"".
I've been down this road, sadly.
1 Prunestand 2017-09-22
But there may not be a rational number in "the middle". So his argument fails.
1 Firzen_ 2017-09-22
Yeah, I know.
1 MrNeoson 2017-09-22
The ordering of the elements in a set doesn't matter. The set {1,2,3,4,5,6,7} is the same as the set {3,5,2,7,1,6,4}. For a countable infinite set like the set of rational numbers Q all the elements can't be listed, but nevertheless there is a clearly defined ordering of the elements in Q allowing the construction of Dedekind cuts:
"It is a partition of the rational numbers into two non-empty sets A and B, such that all elements of A are less than all elements of B, and A contains no greatest element."
Take for example A containing all rational numbers less than 1 and B containing all rational numbers greater than or equal to 1. Then there is no limit to how many rational numbers there are 0.999... yet those numbers are still all elements of Q. A Dedekind cut doesn't add rational numbers to Q.
And it's clearly defined which rational numbers belong to A and which numbers belong to B. And because the ordering of the elements in A and B doesn't matter, there is only one possible split of Q into A and B for each cut.
Therefore the cardinality of the set of all cuts cannot be larger than the cardinality of Q.
1 Redingold 2017-09-22
Since a cut is defined by creating subsets of Q, the number of possible cuts must be less than equal to the number of subsets of Q, which is |P(Q)|. It turns out for this case it's equal, and since |P(Q)| is larger than |Q|, the number of possible cuts is larger than |Q|.
1 Prunestand 2017-09-22
Why? You can "cut" the rational line for each irrational. For example, sqrt(2) will "cut" the real line into two pieces and a such cut won't be considered by your argument.
1 Prunestand 2017-09-22
Yes, it does. Consider a cut for sqrt(2). This cut doesn't have rational "in the middle" as you claim.
1 Prunestand 2017-09-22
You can't do that. Given any two different rational numbers a and b, it's easy to show that (a + b)/2 will lie between a and b.
1 MrNeoson 2017-09-22
Yes, ok my constraint is invalid I see now.
1 almightySapling 2017-09-22
Look up the definition of cut. Depending on whose definition, either A has no "end" or B has no "beginning" so either way what you wrote here isn't true, by definition.
1 MrNeoson 2017-09-22
I recently wrote in another comment: My idea is that there can at most be only one cut between each rational number. And the set of rational numbers Q has the same cardinality (size) as the set of natural numbers N. And since the set of even numbers E also has the same cardinality as N, all the rational numbers can be mapped to E and all the cuts can be mapped to the set of odd numbers O. And E union O = N, i.e. the set of real numbers R is countable.
1 almightySapling 2017-09-22
And your idea would be incorrect.
"Between each rational" doesn't even make sense, think about the words you are using before you hit submit.
You should probably learn what a cut really is before saying more.
1 kogasapls 2017-09-22
A and B are specially defined sets of rationals, not rationals themselves.
1 MrNeoson 2017-09-22
Yet, there can at most be only one cut between each rational number. And as I wrote in another comment: The set of rational numbers Q has the same cardinality (size) as the set of natural numbers N. And since the set of even numbers E also has the same cardinality as N, all the rational numbers can be mapped to E and all the cuts can be mapped to the set of odd numbers O. And E union O = N, i.e. the set of real numbers R is countable.
1 kogasapls 2017-09-22
Your first sentence is critically wrong. Suppose a, b are rationals. Then (a+b)/2 is a rational between them. Then there exists an irrational between a and b, between a and (a+b)/2, and between (a+b)/2 and b. In fact, there are infinitely many rationals between any two rationals, and infinitely many irrationals between any two rationals.
1 MrNeoson 2017-09-22
Think instead of the set of rationals Q as containing an arbitrary ordering of its elements. And for each element in Q there can at most be only one Dedekind cut.
1 Firzen_ 2017-09-22
That's why dedekind cuts are identified by sets and not by rational numbers.
1 kogasapls 2017-09-22
The first sentence is incoherent. Please rephrase your argument.
1 kogasapls 2017-09-22
Dedekind cuts are not defined in terms of two rational numbers, but two special sets of rationals. However the contradiction is obvious even with your incorrect premise. Suppose an ordering gives a,b adjacency. Then let x be irrational s.t. a < x < b. Now suppose another ordering, since your statement should hold for all orderings since your choice was arbitrary, gives the ordering a,c,b. Then there exists an irrational y so a<y<c<b, i.e., a second irrational between x and y.
1 MrNeoson 2017-09-22
My point with arbitrary ordering of Q is to get rid of any ordering comparison. And then for each element of Q assign at most one Dedekind cut.
1 Firzen_ 2017-09-22
You can do that but then your dedekind cuts don't create the real numbers. Instead you defined Q as a subset of R.
1 kogasapls 2017-09-22
If you can't see that this is nonsensical there's no point in discussion. As far as I can tell you're literally assuming without justification that there exists exactly one irrational for every rational.
1 MrNeoson 2017-09-22
No, at most one irrational for every rational. The cardinality of R is still the same as the cardinality of N, even with fewer cuts, i.e. R is countable.
1 kogasapls 2017-09-22
Again, this is entirely without justification. You should review the definition of the reals using Dedekind cuts. Alternately, study Cantor's proof that there cannot exist a bijection from N to R.
1 Prunestand 2017-09-22
But a Dedekind cut is a set of rational numbers and cannot be identified by two specific rationals.
1 kogasapls 2017-09-22
Of course. But the claim that there exists at most 1 irrational between any two rationals is contradicted by the fact that there are infinitely many rationals between any two rationals as I demonstrated.
1 Prunestand 2017-09-22
No, it isn't. Between any real numbers a and b, assuming we don't have a = b, you can find infinitely many rationals as well as irrationals.
1 kogasapls 2017-09-22
I did just say that was true for rationals. It's true for all reals too, as I implied in my previous comment, but it's enough to say it about rationals to disprove the claim about irrationals.
1 Prunestand 2017-09-22
Between any two irrational numbers, you can fine infinitely many rationals and irrationals.
1 kogasapls 2017-09-22
I never disputed it
1 Prunestand 2017-09-22
I read your post wrong. Yeah, I agree with you. There are more than one irrational between two given rationals.
1 Prunestand 2017-09-22
But a Dedekind cut is a set of rational numbers and cannot be identified by two specific rationals.
1 Prunestand 2017-09-22
But a Dedekind cut is a set of rational numbers and cannot be identified by two specific rationals.
1 Prunestand 2017-09-22
But a Dedekind cut is a set of rational numbers and cannot be identified by two specific rationals.
1 Prunestand 2017-09-22
But a Dedekind cut is a set of rational numbers and cannot be identified by two specific rationals.
1 Prunestand 2017-09-22
But a Dedekind cut is a set of rational numbers and cannot be identified by two specific rationals.
1 Prunestand 2017-09-22
But a Dedekind cut is a set of rational numbers and cannot be identified by two specific rationals.
1 Prunestand 2017-09-22
But a Dedekind cut is a set of rational numbers and cannot be identified by two specific rationals.
1 Prunestand 2017-09-22
But a Dedekind cut is a set of rational numbers and cannot be identified by two specific rationals.
1 Prunestand 2017-09-22
Your supposed bijection is not a bijection, since you effectively map all irrationals to infinity.
1 MrNeoson 2017-09-22
See my other comment.
1 satanic_satanist 2017-09-22
It doesn't matter how you defined the real numbers. 0.1010101... and 0.11011011... are still real numbers
1 Yadnarav 2017-09-22
Not trying to make this an insult, but I encourage you to seek some therapy. You seem very paranoid, and this might be a symptom of some larger psychological issue that you'll want to get checked out.
All the best
1 MrNeoson 2017-09-22
Eh.. excuse me, this is the Conspiracy subreddit. What do you expect? Non-mainstream-big-pharma-defined-paranoia? Hahaha.
1 Firzen_ 2017-09-22
Logical consistency how about that?
1 MrNeoson 2017-09-22
You mean like in real numbers with an infinite number of decimals being possible members of a set? ;)
1 Firzen_ 2017-09-22
Yes, that is perfectly logically consistent. Feel free to produce a contradiction and collect your fields medal.
1 EmperorZelos 2017-09-22
And what is inconsistent with that? Nothing about an element in a set says it cannot have infinite decimals.
1 MrNeoson 2017-09-22
So, if the real numbers R is a set, then the element 0.4999... is the same element as 0.5. So how can Cantor use his diagonal argument when many real numbers become fused like that into the same element in R?
1 EmperorZelos 2017-09-22
That is because 0.4999.. and 0.5 are the same element. That is ONE element in the real numbers, it is ONE element with MULTIPLE REPRESENTATIONS, not two elements.
Just as 2/3 and 4/6 are the same element, just different representation.
This is because all elements in reals (and in almost any mathematical strucutre) is not an actual individual element, but a whole set of other elements that are collectively called an equivalence class. These equivalence classes are the the elements in the reals.
1 MrNeoson 2017-09-22
Fair enough, but: "An equivalence class is defined as a subset of the form {x in X:xRa}" -- http://mathworld.wolfram.com/EquivalenceClass.html
So, being a subset, then what is the proof that |R| > |N|? Certainly Cantor's diagonal argument is invalid in this case since lots of representations of the binary strings are collapsed into one element in R.
1 EmperorZelos 2017-09-22
Cantors diagonal argument works still because you can just pick the representations that are most favourable to work with and discard the representations that are not, as you are only discarding representations, not elements.
An alternative method is to use cantors theorem where |S|<|P(S)| and then show that |R|=|P(N)|, which can be done in steps by showing that |P(N)|=|[0,1]|
1 MrNeoson 2017-09-22
A counter argument can be made by representing the real numbers in the interval [0, 1) as a binary tree, where each path from the root and down represents a binary sequence. And then the natural numbers are assigned from the root of the tree left to right level after level. Hence |N| = |R|.
Cantor used a similar method when assigning the natural numbers to the set of rational numbers:
"Proposition 2. The set of rational numbers Q is countably infinite.
... The thing to notice is that given such a list of all elements of S, we can easily construct a bijection from N to S by sending 1 to the first term in the list, 2 to the second, and so on ..." -- http://www.math.northwestern.edu/~scanez/courses/300/notes/cardinality.pdf
1 EmperorZelos 2017-09-22
No, cause you only get FINITE digits, and none of the infinite digits, ergo it doesn't work as it is not surjective.
1 MrNeoson 2017-09-22
Yes, you are correct. But what if I add a cut between each node in the (infinite complete) binary tree? And the cuts represent infinite number of digits.
1 EmperorZelos 2017-09-22
Then it is no longer to the natural numbers. It doesn't matter how you try, Cantors thing showed it cannot be done.
1 EmperorZelos 2017-09-22
The beauty of cantors theorem is that no matter what list you think you can come up with in any fashion, NO MATTER WHAT LIST!, he can produce an element you missed. It doesn't matter how good you think the list is, you have missed some elements.
To even have a chance to defeat it you would have to show cantors theorem wrong. Something you cannot as it is possible to prove in multiple different methods.
1 MrNeoson 2017-09-22
I found a YouTube video where the presenter says that there is a problem with the Axiom of Choice allowing infinite sequences of digits: https://www.youtube.com/watch?v=4DNlEq0ZrTo&t=23m20s
1 EmperorZelos 2017-09-22
Yeah no, that is a nutorious crank and you shouldn't listen to him.
1 MrNeoson 2017-09-22
Ok, yes you could be right. I made an amateurish definition of the set of real numbers earlier that actually has numbers with an infinite number of decimals. The example is for the interval [0, 2) but can easily be scaled to [0, 1):
N = {0, 1, 2, ...} is the set of natural numbers.
T = {1, 1/2, 1/4, ...} which is 2-n for all elements n in N.
P = 2T = {{}, {1}, {1/2}, {1/4}, {1, 1/2}, {1, 1/4}, {1/2, 1/4}, {1, 1/2, 1/4}, ...}
The power set P of T contains subsets of rational numbers in such way that the combinations represent all real numbers in the interval.
And for example in the video the presenter said iirc that it's impossible to make a general equality comparison of two real numbers because of the possibility of an infinite number of decimals. Yet with my definition, value x and y are equal iif x and y are the same member in P. That's just a basic set comparison. (Of course 0.999... is then a different number than 1.0 but I think that's valid.) Maybe even addition and so on can be defined for P.
1 EmperorZelos 2017-09-22
Your P can be put into a surjection with the real numbers, but not a bijection, as it contains duplicates.
There is where youre definition fails, because in your P, two sets represent the same real number.
The guy you linked to is a finitist and a crank. Please do not use him, you will only do yourself a disfavour.
1 MrNeoson 2017-09-22
No, P doesn't contain duplicates. Adding the rational numbers in each subset gives a unique sum for each element in P such as {0, 1, 0.5, 0.25, 1.5, 1.25, 0.75, 1.75, ...}.
1 EmperorZelos 2017-09-22
it contains duplicates because it has the subset {1} and the subset {0,0.5,0.25,0.125,....} and {0.5,0.25,0.125,....} which all represent the same number
1 MrNeoson 2017-09-22
No, because zero is not a member of T. And I found this:
"Indeed one way of defining the real numbers, R, is as limits of sequences of rational numbers." -- https://www.quora.com/How-can-e-the-sum-of-many-rationals-be-irrational
So then it's possible to construct a new set D which is the limits of the sums of the rational numbers in each element in P. And then for example 0.4999... = 0.5. And then D is exactly the real numbers in the interval [0, 1] (If I start the natural numbers from 1 instead of 0). That's a much cleaner definition than using Dedekind cuts!
1 EmperorZelos 2017-09-22
Even then you got 2 sets being the same real number so the issue persists.
Actually it isn't as that assumes a craptonnes of things, for example it assumes a priori 1: The limit existing, which, if you only have rational numbers, most don't 2: It assumes you can do a sum of inifnitely many terms, which in rational numbers you cannot so there is an issue there.
To name a few, it is an increadibly ugly definition as it assumes a craptonne of things.
When you start going to the root of things for limits and all, defining what a limit is, you still suffer rom the limit not existing as an element. So to create this we need to use other things. This is where dedekinds cuts come in, we have the ability, by ZFC, to create sets like that and can show it will create the neccisery limits we desire.
We can also use cauchy sequences and do the same.
1 MrNeoson 2017-09-22
Notice that P is simply a representation of the collection of all possible infinite binary sequences. And with limits of sums there will be several limits that "fuse" into the same real number, such as 0.499... = 0.5, but that's exactly the same as what happen in the usual definitions of the set of real numbers.
But ok, defining limits of infinite sums is perhaps tricky.
1 EmperorZelos 2017-09-22
It is because the limit, when you only have rationsl, most often does not exist.
So when you ask for the limit, there is no limit to pick.
1 MrNeoson 2017-09-22
Hmm... So you mean for example that the irrational number e = sum(1/n!) is a case where a limit is possible to find, but that in general there is no way of determining such limits for all irrationals?
1 EmperorZelos 2017-09-22
No, I say that without constructing it PRIOR to doing the limit, the number e doesn't exist!
You asking for an object that you have not yet constructed mathematicly which is non-sense. It is like asking for the sum of all natural numbers squared, it doesn't make sense to proclaim something as "the limit" without first constructing the object before and then show it satisfies the criteria of being the limit.
1 MrNeoson 2017-09-22
But defining a limit of the sums in my case is easy. The worst case scenario is the binary sequence 0.111111111... which has the limit 1.0. All other limits of the sums are smaller than or equal to that (no negative numbers involved). The sums of the rational numbers in the elements in P are therefore guaranteed to converge.
1 EmperorZelos 2017-09-22
You are assuming the limit exists already.
1 MrNeoson 2017-09-22
The binary sequences have the form (b1, b2, b3, b4, b5, ...) where b_n can be either 0 or 1. Except for the case where all b_n are zero there is an m where b_m = 1 and for all k < m, b_k = 0. And sum(b_n/2n ) for n = m+1 to infinity is always less than 1/2m .
And for any p > m, sum(b_n/2n ) for n = p to infinity is always less than sum(b_n/2n ) for n = 1 to p-1.
Therefore the sums of all the binary sequences converge to a limit.
1 EmperorZelos 2017-09-22
Again, you assume that the limit exists which it may not do and in the rational number cases, msot don't.
1 MrNeoson 2017-09-22
Another alternative is to skip the limits and use the sums directly with the following axiom:
Axiom of Infinite Fraction Sum: The sum of an infinite number of digits in base b following the radix point in positional notation is a unique real number in the interval [0, 1) represented by the sequence of digits itself.
This removes the fusion conspiracy of the real numbers, so that for example 0.4999... != 0.5. In the traditional definitions of the set of real numbers R there are cases of fusion such as 0.999... = 1.0 which makes it impossible to distinguish whether that element in R belongs to the interval [0, 1) or belongs to the interval [1, 2).
1 EmperorZelos 2017-09-22
it is trivial to determine that 0.999... is not in [0,1) and that "axiom" is problematic in on itself, you are trying to define real numbers there but your definition will fail several key properties we have decided that the real numbers must satiesfy.
For starters, basic operations like multiplication, addition and division don't work properly.
1 MrNeoson 2017-09-22
I think the supremum property can be achieved by defining the less than and greater than operators. First the equality operator == is defined:
∀x∀y(({x}∪{y}={x} → x==y) ↔ (y==x))
And then the less than < and the greater than > operators:
∀x∀y(¬(x==y) → (x<y ↔ y>x))
And then partial order:
∀x(x≤x)
∀x∀y((x≤y ∧ y≤x) → x==y)
∀x∀y∀z((x≤y ∧ y≤z) → x≤z)
And lastly:
∀x∀y((¬(x==y) ∧ x≤y) → x<y)
1 EmperorZelos 2017-09-22
That doesn't work unfortunately as ordering of sets is only a partial ordering, it is not a total ordering.
1 MrNeoson 2017-09-22
I found: "4. Comparability (trichotomy law): For any a,b in S, either a<=b or b<=a.
The first three are the axioms of a partial order, while addition of the trichotomy law defines a total order." -- http://mathworld.wolfram.com/TotallyOrderedSet.html
Then for total ordering, the following condition is added:
∀x∀y(x≤y ∨ y≤x)
But yes, it is different than the set of real numbers, because in my definition for example 0.4999... is a different number than 0.5 whereas in the set of real numbers they are the same (due to the use of limits I assume).
Instead of the set of real numbers R it can be called the set of standard numbers D, by forming numbers z.f where z is an integer and f is a member of P (the power set of T I defined earlier):
D = {z.f | z∈Z, f∈P}
1 EmperorZelos 2017-09-22
Trichotomy is a property in an ordered set that says for any 2 elements a, b in S, that a<b, a=b or a>b, and only one at a time.
Which also kills the supremum property, your system doesn't have it and CANNOT have it.
Again, why would you do this? This satisfies none of the properties we want and have wonky things such as as not all elements are comparable and even your definition z.f is non-sense. You haven't said what kind of structure it really is. You can go with ordered pair (z,f) but how do you compare then? (z,f)>(x,g) when what?
z>x and g is subset of f?
You have illdefined things and you cannot throw any number of axioms at something and hope it works, your thing is incoherent selfdefeating.
I ask you, why are you doing this?
1 TiggersMyName 2017-09-22
Ok that's a reasonable question. If you suppose a map from the natural numbers to R and follow cantors argument to obtain a new real number which wasn't mapped to, the new one has only 0s and 1s. The trick is that whenever there was a '9' in the binary expansion of the nth real number mapped to, we have to be sure to make the nth digit of our new number 1 rather than 0. if we do this then there is no way that the new number was already in the sequence. (because we would have to have repeating 9s which is the same as a 0, not a 1).
That's a good question though, and a subtlety of the argument which is important to notice.
1 TomSwirly 2017-09-22
I am a mathematician. Your proof is wrong from the get-go.
You define
S
to be[0, 1]
- the set of all the real numbers from 0 to 1 - and then claim that the functionn
is a bijection fromN
ontoS
.However, the very first example you give,
n(x) = 2^0 + 2^3 + 2^4 + 2^6 + ...
does not in fact give you a number inS
, i.e. a real number between0
and1
- indeed, the sum seems to be unbounded ("goes to infinity").So you're obviously badly confused already.
In order to go further, I'd have to try to guess what "bijection" you really meant to talk about, which I'm not going to do. My idea is that if you cleaned up what you meant, you would eventually get a function
n
into[0, 1]
but that it would be an injection - a function that's one-to-one but not onto.As you can imagine, I'm very very very very doubtful you have a proof that the real numbers are countable. Were this true, all of measure theory and so basically all of calculus would be grossly inconsistent. But calculus does actually work - bridges stay up, airplanes don't fall out of the sky and so on.
However, if you're interested in going on, if you clean up your "bijection" I'll take a look at it for you.
1 MrNeoson 2017-09-22
The function n(x) gives a natural number. And x is a real number in [0, 1). Ok, let me try to define an inverse function of n(x) to show that it's really a bijection.
First n is represented in binary form, such as 12 = 1100, and ni is the bit at position i.
s(n) = sum(1/(2ni))
Q.E.D. :D
1 TomSwirly 2017-09-22
This new function is a mapping from the natural numbers to all decimals of a finite length. It is an injection - indeed, it misses almost all numbers in
[0, 1]
.For example, which natural number x gives you 1/sqrt(2) as a result? (Heck, which natural number gives you 1/3 as a result?)
1 MrNeoson 2017-09-22
You seem to assume that a real number can have an infinite number of decimals. I claim that that's false. So, yes all real numbers have a finite (yet some unending) number of decimals.
And therefore s:N->S and n:S->N form a bijection (there is a one-to-one mapping between the elements in set S and N).
1 Qqaim 2017-09-22
Wait, what? What's the decimal expansion of 1/3 then? Or π? If reals can only have finitely many decimals, then they'd all be rational...
1 MrNeoson 2017-09-22
Well, consider for example e = sum(1/n!). Adding two rational numbers results in a rational number. The same is therefore true for this sum tending to infinity. So e is then, actually a rational number.
1 Firzen_ 2017-09-22
The sum of two natural numbers is always finite. So if I sum together infinitely many natural numbers, their sum must also be finite.
See some similiarities and an obviously wrong conclusion?
Induction does not apply to the limit case.
1 MrNeoson 2017-09-22
Yes, that sum has a finite number of digits, or else it's not a natural number.
"By induction, we conclude that S=NS=N. That is, every natural number has only finitely many digits when written in base 10 with no leading 0s." -- https://math.stackexchange.com/questions/58085/a-number-with-an-infinite-number-of-digits-is-a-natural-number
1 Firzen_ 2017-09-22
Exactly!
Induction allows you to prove something for every natural number, which notably doesn't include infinity.
So what makes you think that your argument for e being rational should be true? Where is the difference between your line of arguing and my argument that an infinite sum of natural numbers is finite?
1 MrNeoson 2017-09-22
If e has a finite yet unending number of decimals, then yes it's a rational number, at least if the formula e = sum(1/n!) is correct.
1 Firzen_ 2017-09-22
What on earth does "finite yet unending" even mean?
That's an oxymoron if I've ever seen one.
1 MrNeoson 2017-09-22
Take the natural numbers for example. How many digits can a natural number have? The answer is: only a finite number of digits.
1 Firzen_ 2017-09-22
Yes and since it's finite it's ending. Explicitly not unending.
1 Prunestand 2017-09-22
"Finite" and "unending" are contradictory.
1 skysurf3000 2017-09-22
Why?
1 MrNeoson 2017-09-22
Because 1/1! + 1/2! + 1/3! + ... is a rational number. No matter how many additions are made like that, the sum remains a rational number.
1 skysurf3000 2017-09-22
You have that for any n, 1/1! + 1/2! + 1/3! + ... + 1/n! is a rational number. My question is: why does that imply that the result of the infinite sum is a rational number?
For example you also have that for all n, the set {1,2,3,...,n} is finite. But that does not imply that the set {1,2,3,...} is finite.
1 MrNeoson 2017-09-22
Take the last example, my claim is that 1/n is never zero for any n.
1 skysurf3000 2017-09-22
So your claim is that 1/1! + 1/2! + 1/3! + ... + 1/n! is rational for any n.
Not that 1/1! + 1/2! + 1/3! + ... is rational.
1 MrNeoson 2017-09-22
It depends on what is mean by an infinite series. Usually it means that the sum is done with an iteration of n that tends to infinity, not that n reaches infinity.
1 Firzen_ 2017-09-22
You what? An "uncomplete" infinite series is called a partial sum. An infinite series reaches infinity, hence infinite series.
1 skysurf3000 2017-09-22
But e is equal to the infinite sum 1/1! + 1/2! + 1/3! + ...
It is not equal to any 1/1! + 1/2! + 1/3! + ... + 1/n!, whichever n you choose.
1 Prunestand 2017-09-22
An series is always a limit. Otherwise, it's just a sum.
1 Prunestand 2017-09-22
An series is always a limit. Otherwise, it's just a sum.
1 Qqaim 2017-09-22
You're assuming that something true for finite sums is also true for infinite sums, which is not true.
Other than that, you haven't answered what the decimal expansions of 1/3 or π are (and we can add e to that list) since they're finite according to you.
1 MrNeoson 2017-09-22
The expansion of 1/3 in binary form is: 0.01010101...
The expansion of e is sum(1/n!).
Infinite sums of natural numbers always results in a natural numbers, and all natural numbers have a finite number of digits.
1 positron_potato 2017-09-22
Can you name one example of when this is the case? It's not possible unless you mean rational numbers instead of natural numbers, and even then it's not guaranteed. Infinite sums of rational numbers are often not rational.
You seem to think that inductance can tell you anything beyond finite cases, which is not true. As soon as you 'go to infinity' inductance goes out the window.
1 MrNeoson 2017-09-22
It's always the case! Adding natural numbers always results in a natural number. You can never go "outside" of the set of natural numbers N so to speak.
The set N itself is infinite (or transfinite) yet the natural numbers always only have a finite number of digits.
1 positron_potato 2017-09-22
You misunderstand me. Can you give me an infinite list of natural numbers and then tell me what they sum up to?
For example, what is 1+1+1+1+...?
1 MrNeoson 2017-09-22
First we need to define what we mean by 1+1+1+...
I claim that it's a sum as a result of endless repeated adding of 1, which is NOT the same as an infinite number of additions. And I guess that you mean that it means an infinite number of additions, but then you need to define infinity. What do you mean by infinity?
1 positron_potato 2017-09-22
Interpret it however you like. You said it equals a natural number. which natural number? If you can't tell me then I have no reason to take you seriously.
1 MrNeoson 2017-09-22
The sum equals ω-1, where ω is the smallest ordinal greater than every natural number.
1 positron_potato 2017-09-22
ω-1 does not exist. If it did, it would imply that there is a largest natural number, which would imply that there are only finitely many natural numbers. So what is the sum equal to, if it is a natural number? If the sum is a natural number, then it must have a finite number of digits, so must be expressible in decimal (or binary) representation.
1 MrNeoson 2017-09-22
From a philosophical viewpoint, I claim ω-1 does exist. At each moment in time there is a defined natural number ω-1. However, in the next moment ω-1 has increased. So from a mathematical perspective we can take a snapshot in time and deal with ω-1 as a uniquely defined natural number.
1 positron_potato 2017-09-22
This is math, not philosophy.
There is no definition of the natural numbers that has them depend on the time. None of this makes any sense. I asked you to produce a natural number that is equal to 1+1+1+1+..., and you keep dancing around the issue. The number either exists, in which case it can be written down in decimal notation, or it cannot. The fact that you keep resorting to new symbols or pseudo-philosophy to describe this sum tells me that you are unable to evaluate it as a natural number.
1 MrNeoson 2017-09-22
As I pointed out to Firzen_, there are no ended infinite processes. And using that kind of false construct in mathematics is a part of the conspiracy to mislead the public scientific community.
It's a similar problem with the claim that real numbers can have an infinite number of decimals while at the same time claiming that infinity is not a number. Another false conspiracy construct.
1 positron_potato 2017-09-22
Why not? Math processes don't take time, they're just done. Can you give me a good reason why 1+1/2+1/4+1/8+... doesn't equal 2?
If everything follows sound logic and works out to be consistent, then why shouldn't we be able to consider things like infinite sums?
That's not a problem at all. You can have infinite numbers, but these are usually ordinal numbers like you mentioned earlier, or cardinal numbers, such as in this case. Real numbers can have up to an Aleph_0 amount of digits, and there's no reason why they shouldn't.
1 MrNeoson 2017-09-22
I have heard that philosophers debate about whether ending infinite series is allowed or not. Personally I think one cannot iterate up to and including infinity, but it's debatable it seems.
1 positron_potato 2017-09-22
While we are not required for things in mathematics to conform to reality, let's consider a real world example of an infinite number of steps that can be completed in finite time.
Imagine you are on one side of a room. Your first task is to make it to the middle of the room. Your second task is to make it half way between that point and the far wall. Your third is to make it half way again, and so on. Clearly you have infinite tasks, but these can be completed in finite time by just crossing the room.
So even in the real world (which math is not limited to) there is no problem with infinite sums/processes.
1 MrNeoson 2017-09-22
As I see it, space is quantized. With a continuum movement is actually impossible.
1 Firzen_ 2017-09-22
If you can describe how space is quantized go get your nobel prize in physics right now!
1 positron_potato 2017-09-22
Is there any evidence that space is quantized?
1 MrNeoson 2017-09-22
You have ask Leonard Susskind about that. :) (I'm not an expert)
1 EmperorZelos 2017-09-22
Do you still think this junk?
1 MrNeoson 2017-09-22
No, my power set construction actually has numbers with an infinite number of decimals. And at least from an abstract mathematical perspective that's valid. Are there any actual objects like that in physical reality, such as a continuum? No, I don't think so, but as a precise mathematical definition it seems valid to have an infinite number of decimals.
1 EmperorZelos 2017-09-22
Who cares about reality?
1 Firzen_ 2017-09-22
Please, actually read up on this instead of spreading misinformation.
You can claim that ω-1 exists all you want if you can't prove or define it in a consistent way it doesn't matter.
The natural numbers aren't in a state of flux. They are a set that is static and unchanging. They are described by an infinite process, but the actual set is the result of the finished process.
1 MrNeoson 2017-09-22
From a philosophical perspective there are no such things as ended infinite processes. So I don't see how you can use that false construct in mathematics. Well, I CAN see it, in a conspiracy theory perspective.
1 Firzen_ 2017-09-22
This isn't philosophy, this is math. And even if it were philosophy then that obviously contains a notion of completed infinite processes as well. You yourself invoked Zenos paradoxes earlier. The fact that you can move shows you that you can complete an infinite process.
It is used everywhere in mathematics, that's what limits are, that's what the natural numbers are. There are extensive proofs for when talking about a completed infinite process makes sense and when it doesn't.
Your lack of basic mathematical knowledge doesn't mean there is a grand conspiracy, it means that you have a lot to learn and would rather believe that there is a massive conspiracy than that your intuition might be wrong.
1 Prunestand 2017-09-22
This is trivially false unless you consider 0 a natural number. Either case, limits don't have to be rational. So you're double wrong.
1 plumpvirgin 2017-09-22
No, just answer his very simple question: what is the decimal expansion of 1/3? If you can't answer that, then there's no point discussing anything with you. Don't avoid a very simple question by diverting attention to another one.
1 MrNeoson 2017-09-22
The decimal expansion of 1/3 is 0.3333... And ok, real numbers can have an infinite number of decimals, when using Cantor's infinite sets. But I still have doubts about the continuum and think that it's an abstraction without basis in physical reality.
1 Prunestand 2017-09-22
Who said mathematics was an empirical science? Show me the number 1 please.
1 EmperorZelos 2017-09-22
Congratulation, welcome to mathematics. We do not care about physical reality.
1 Prunestand 2017-09-22
This is false. A rational Cauchy sequence does not have to converge in the field of rational numbers.
1 EmperorZelos 2017-09-22
What is true for any amount of finite cases does notm ean it is true for the infinite case.
For any given finite set, if I attatch another element to this set, i get another finite set. This happens for any number of finite amount of itmes I do it, but if I do it infinitely, I have an infinite set!
1 EmperorZelos 2017-09-22
MrNeson you moron. Real numbers CAN have infinite decimals, that is one of their properties. Those with finite decimal expansions are 10-adic rationals which is a subset of rational numbers which is known to be countable.
So you have not proven anything new, but your own ignorance.
For your proposition to be true, you must find a rational number that gives squareroot of 2, but that doesn't exist so squareroot of 2 CANNOT have finite decimal expansions.
1 EmperorZelos 2017-09-22
WHat natural number do you get from \sqrt(2)/2?
1 -3than 2017-09-22
HAHAHAHAHAA
1 Gurkenglas 2017-09-22
Read this. http://lesswrong.com/lw/j8/the_crackpot_offer/
1 MrNeoson 2017-09-22
It's fairly simple math actually. What the experts do is try to obscure embarrassing past errors like that with all kinds of extremely complicated mathematical detours to distract from having to admit it's a collective mistake. They desperately need to save face to uphold their seeming credibility in the eyes of the laypeople, which serves the deep state scientific community well since it hampers progress in the public scientific community.
1 MrNeoson 2017-09-22
That's the conspiracy! Real numbers don't have an infinite number of decimals. And since the set of real numbers R can be defined using Dedekind cuts, and the number of those cuts is not larger than the number of rational numbers, R is countable. So the public scientific community has to whitewash and cover up that early deliberate mistake.
1 MrNeoson 2017-09-22
Each cut only defines one unique number, and a pair of rationals with minimal difference are the end of A and the beginning of B:
"... that cut defines a unique irrational number which, loosely speaking, fills the "gap" between A and B. In other words, A contains every rational number less than the cut, and B contains every rational number greater than or equal to the cut." -- https://en.wikipedia.org/wiki/Dedekind_cut
1 Neuro_Skeptic 2017-09-22
That's incorrect, but even assuming it was true, what does this have to do with "the deep state"?
1 Friek555 2017-09-22
Okay, let's take 1/3 and calculate your function: 1/3=0.01010101... in binary. So n(1/3)=22+24+26+28, this clearly diverges. So your function n does not map to the natural numbers. And even if you extend the natural numbers to include infinity, you would still get n(1/3)=n(2/3)=infty, so n would not be a bijection because is wouldn't be injective.
1 shaggorama 2017-09-22
Knock yourself out: neither does OP.
1 almightySapling 2017-09-22
And your idea would be incorrect.
"Between each rational" doesn't even make sense, think about the words you are using before you hit submit.
You should probably learn what a cut really is before saying more.
1 MrNeoson 2017-09-22
Yes, that sum has a finite number of digits, or else it's not a natural number.
"By induction, we conclude that S=NS=N. That is, every natural number has only finitely many digits when written in base 10 with no leading 0s." -- https://math.stackexchange.com/questions/58085/a-number-with-an-infinite-number-of-digits-is-a-natural-number
1 Firzen_ 2017-09-22
That's why dedekind cuts are identified by sets and not by rational numbers.
1 kogasapls 2017-09-22
The first sentence is incoherent. Please rephrase your argument.
1 kogasapls 2017-09-22
Dedekind cuts are not defined in terms of two rational numbers, but two special sets of rationals. However the contradiction is obvious even with your incorrect premise. Suppose an ordering gives a,b adjacency. Then let x be irrational s.t. a < x < b. Now suppose another ordering, since your statement should hold for all orderings since your choice was arbitrary, gives the ordering a,c,b. Then there exists an irrational y so a<y<c<b, i.e., a second irrational between x and y.
1 skysurf3000 2017-09-22
You have that for any n, 1/1! + 1/2! + 1/3! + ... + 1/n! is a rational number. My question is: why does that imply that the result of the infinite sum is a rational number?
For example you also have that for all n, the set {1,2,3,...,n} is finite. But that does not imply that the set {1,2,3,...} is finite.
1 qlikers 2017-09-22
Can you explain dedekinds cut to me?
1 Firzen_ 2017-09-22
The square root of 2 isn't rational.
You don't get to at most |Q|. /u/MrNeoson doesn't know what he's talking about.
1 MrNeoson 2017-09-22
The cut is defined by the numbers in A and B. There are no subsets in A or B. For example the subsets {1/2} and {1/2, 1/3} are not rational numbers.
1 Firzen_ 2017-09-22
I agree that it seems false. It's certainly unintuitive.
But there are many ways to prove it. I wrote down a proof for that in our conversation here.
Just, you know, turn down your arrogance a tad. Those are basic concepts that anyone with a higher math education knows and you think you are overthrowing established knowledge without fully grasping it.
1 MrNeoson 2017-09-22
As I pointed out to Firzen_, there are no ended infinite processes. And using that kind of false construct in mathematics is a part of the conspiracy to mislead the public scientific community.
It's a similar problem with the claim that real numbers can have an infinite number of decimals while at the same time claiming that infinity is not a number. Another false conspiracy construct.
1 Firzen_ 2017-09-22
That's just plain wrong.
1 Roxor99 2017-09-22
Well since that isn't a rational number your whole bijection falls apart.
1 MrNeoson 2017-09-22
Ok, but here is another problem: "Let D be the set of all non-selfish natural numbers. By definition, the power set 𝒫(ℕ) contains all sets of natural numbers, and so it contains this set D as an element. If the mapping is bijective, D must be paired off with some natural number, say d."
It's possible to construct a pairing with no non-selfish numbers: n <-> {n, ...} and then D is the empty set and there is no number d.
1 Prunestand 2017-09-22
This is simply not true, since there are more cuts than rational numbers.
1 Prunestand 2017-09-22
But that doesn't work for irrationals.
1 MrNeoson 2017-09-22
So, if the real numbers R is a set, then the element 0.4999... is the same element as 0.5. So how can Cantor use his diagonal argument when many real numbers become fused like that into the same element in R?
1 EmperorZelos 2017-09-22
Trichotomy is a property in an ordered set that says for any 2 elements a, b in S, that a<b, a=b or a>b, and only one at a time.
Which also kills the supremum property, your system doesn't have it and CANNOT have it.
Again, why would you do this? This satisfies none of the properties we want and have wonky things such as as not all elements are comparable and even your definition z.f is non-sense. You haven't said what kind of structure it really is. You can go with ordered pair (z,f) but how do you compare then? (z,f)>(x,g) when what?
z>x and g is subset of f?
You have illdefined things and you cannot throw any number of axioms at something and hope it works, your thing is incoherent selfdefeating.
I ask you, why are you doing this?
1 EmperorZelos 2017-09-22
And also 1.999... which makes it not unique