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