Skip to main content
Search type Search syntax
Tags [tag]
Exact "words here"
Author user:1234
user:me (yours)
Score score:3 (3+)
score:0 (none)
Answers answers:3 (3+)
answers:0 (none)
isaccepted:yes
hasaccepted:no
inquestion:1234
Views views:250
Code code:"if (foo != bar)"
Sections title:apples
body:"apples oranges"
URL url:"*.example.com"
Saves in:saves
Status closed:yes
duplicate:no
migrated:no
wiki:no
Types is:question
is:answer
Exclude -[tag]
-apples
For more details on advanced search visit our help page
Results tagged with
Search options answers only not deleted user 23141

the mathematical discipline that applies mathematical methods to the study of mathematical theories themselves.

4 votes

How necessary is Godel's Condensation Lemma

It's been 25 years since I struggled through it, but I clearly remember that Godel's book Consistency of the Axiom of Choice and of the Generalized Continuum Hypothesis with the Axioms of Set Theory g …
Nik Weaver's user avatar
  • 42.8k
12 votes

Which kind of foundation are mathematicians using when proving metatheorems?

One direction could go like this. Let ${\rm ZFC}^+$ be the theory in the language of set theory augmented by a constant symbol ${\bf M}$ with the axioms $\bullet$ every axiom of ${\rm ZFC}$ $\bullet …
Nik Weaver's user avatar
  • 42.8k
3 votes

How can you formalize the metamathematics conventionally used to state Godel’s theorem?

I think this question is clearly asking for provability logic. This is the basic modal logic K with the additional axiom $$\square(\square A \to A) \to \square A.$$ "$\square A$" is interpreted as " …
Nik Weaver's user avatar
  • 42.8k
6 votes

Formal proof of Con(ZFC) => Con(ZFC + not CH) in ZFC

The other answers are perfectly correct, but I'd like to add that the implication Con(ZFC) $\to $Con(ZFC + $\neg$CH) is not only provable in ZFC, it is provable in Peano arithmetic. I consider this a …
Nik Weaver's user avatar
  • 42.8k