18 Answers votes newest views recent 12What are the most attractive Turing undecidable problems in mathematics? (2) -7What would you want to see at the Museum of Mathematics? 4What’s your favorite equation, formula, identity or inequality? 4Are there any very hard unknots? 0What is Realistic Mathematics? 1Arguments against large cardinals 3Would Euler’s proofs get published in a modern math Journal, especially considering his treatment of the Infinite? 6Writing “Semi-Formal” Proofs 1Can we color Z^+ with n colors such that a, 2a, …, na all have different colors for all a? 0“Simpler” statements equivalent to Con(PA) or Con(ZFC)? 0A decision problem in graph coloring 5Ask for recommendations for textbook on mathematical logic 1What is the reverse mathematics of first-order logic and propositional logic? 2Are any natural examples of Gödel speed-up known? 1How to prove Con(PA) in ZFC? 1Can invariant of transitive reflexive closure in FOL+PA always been proven? 1Measuring how “heavily linked” a node is in a graph 0Remove unnecessary dependencies in a task graph?