What’s hot at mathoverflow 17/17

3D Billiards problem inside a torus

71, the Monster, and c = 24 CFTs

What’s with equivariant homotopy theory over a compact Lie group?

Kodaira-Spencer maps and deformation theory

Solving ODE via contact geometry

Does every Coxeter group arise from a BN-Pair? Does \(PGL_2({\mathbb Z})\)?

Are countable dense subspaces of \({\mathbb R}^n\) homeomorphic to \({\mathbb Q}^n\)?