21 Answers votes newest views recent 9What are some examples of ingenious, unexpected constructions? -2Set theories without “junk” theorems? 1A result of Shelah about the nonstationary ideal 2Why are some axioms preserved in generic extensions? 1The set-theoretic multiverse as a (bi)category 4Are there examples of statements that have been proven whose consistency proofs came before their proofs? 1M.A.D family question 5Intended interpretations of set theories 2If a result is apparently provable with AC, is actually independent of ZF? 29A Book You Would Like to Write 17Awfully sophisticated proof for simple facts 2An ordinal invariant for spaces based on a hierarchy of closed sets from z-sets 1Why is it OK to rely on the Fundamental Theorem of Arithmetic when using Gödel numbering? 0What is your favorite proof of Tychonoff’s Theorem? 3Which mathematicians have influenced you the most? 5Examples of non-metrizable spaces -3Most intricate and most beautiful structures in mathematics 3Topological Rings 1Distinct well-orderings of the same set 4Proving theorems by using functions with fixed points. 6What are some reasonable-sounding statements that are independent of ZFC?