? about Godel's incomplete theorm

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Discussion Overview

The discussion revolves around Gödel's incompleteness theorem, its implications, and its applicability to various branches of mathematics. Participants express confusion about the theorem's use, particularly in relation to statements that are unprovable and its relevance to concepts like the equality of 0.999... and 1.

Discussion Character

  • Exploratory
  • Debate/contested
  • Technical explanation

Main Points Raised

  • Some participants seek clarification on when Gödel's theorem is applied and what specific statements are unprovable, noting its apparent non-application to Euclidean geometry.
  • One participant asserts that the theorem indicates the existence of undecidable statements but does not specify what they are, mentioning examples like the Continuum hypothesis and Goodstein's theorem.
  • Another participant argues that the claim linking Gödel's theorem to the assertion that 0.999... does not equal 1 is a misuse of the theorem, emphasizing that this equality follows from the definition of the base 10 numeration system.
  • Some participants express skepticism about the validity of arguments that misuse Gödel's theorem, suggesting that those who do so may lack understanding of the theorem itself.
  • There is a correction regarding the terminology, clarifying that it is the "incompleteness" theorem, not "incomplete," and discussing the nature of the theorem's proof and its implications for axiomatic systems.

Areas of Agreement / Disagreement

Participants generally disagree on the application of Gödel's theorem to specific mathematical statements and concepts, particularly regarding the equality of 0.999... and 1. There is no consensus on the validity of the claims made by those who misuse the theorem.

Contextual Notes

Participants note that finding specific undecidable statements is complex and that Gödel's theorem does not provide explicit examples of such statements.

raven1
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I read the theorem and the proofs, but what i am unclear about is when is it used or what statements are unprovable. as far as i know it doesn't apply to Euclidean geometry so what branchs of math does it apply. part of the reason i am asking is on another website i seen someone try to use this theorem to show that .99... does not equal 1 and math itself is very flawed , i felt that the theorem is being misused but i probably shouldf learn more before i say anything
 
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First, it is "incompleteness" theorem, not "incomplete" theorem. The theorem itself is complete. Essentially, it says that in any axiom system large enough to include the natural numbers is "incomplete"- that is that there exist statement which can neither be proven nor disproven. The proof of that theorem itself "constructs" a statement that can be proven nor disproven but in a very abstract way- it uses a way of assigning numbers to statements (the Godel numbering) such that the statement assigned a certain number be shown to neither provable nor disprovable- but doesn't tell us exactly what that number is and certainly not what the theorem is. Indeed, given a statement that cannot be proven nor disproven, we could take that statement (or its negation) as an axiom and have a new system- which would then have a new statement that could not be proved nor disproved.

I can't imagine that having anything to do with 1= 0.999... That follows immediately from the definition of the base 10 numeration system.
 
As either Halls or Hurkyl is very keen to point out, the theory of Real Fields is complete and not remotely susceptible to this line of attack. Please post a link to this person's attempted disproof; I'm sure many people here would like to point out their egregious error.
 
raven1 said:
I read the theorem and the proofs, but what i am unclear about is when is it used or what statements are unprovable. as far as i know it doesn't apply to Euclidean geometry so what branchs of math does it apply. part of the reason i am asking is on another website i seen someone try to use this theorem to show that .99... does not equal 1 and math itself is very flawed , i felt that the theorem is being misused but i probably shouldf learn more before i say anything
First off, godel's theorem talks about the existence of such a statement. It doesn't tell us what they are. Finding one/showing that a statement is undecidable is a lot harder. Examples: The Continuum hypothesis was shown to be undecidable within ZFC. I also know that the Goodstein's thoerem is an undecidable statement within peano arithmetic, however it can be proven with a stronger system. Whoever used godel's thm. to show that .999... does not equal 1 is 99.999999% probably a crackpot that has no idea what they are talking about.
 
Last edited:
matt grime said:
As either Halls or Hurkyl is very keen to point out, the theory of Real Fields is complete and not remotely susceptible to this line of attack. Please post a link to this person's attempted disproof; I'm sure many people here would like to point out their egregious error.

I started to ask for a link but then it occurred to me that I waste entirely too much time on that sort of thing already!
 

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