15 Answers votes newest views recent 3analogue of a set with n binary operations 0Euclidean inside Hyperbolic 2Time scale calculus vs Lebesgue–Stieltjes calculus 4What are some examples of colorful language in serious mathematics papers? 3Proofs that require fundamentally new ways of thinking 5More open problems 2Suggestions for good notation 1What is the indefinite sum of tan(x)? 2Modern algebraic geometry vs. classical algebraic geometry 1Books you would like to see translated into English. 2Statements reliant on conjectures 2How should the Math Subject Classification (MSC) be revised or improved? 2Quick proofs of hard theorems 10Consolidation: Aftermathematics of fads 3why haven’t certain well-researched classes of mathematical object been framed by category theory?