20 Answers votes newest views recent 6Is there a simplicial volume definition of Chern Simons invariants? 5When is a Riemannian metric equivalent to the flat metric on $\mathbb R^n$? 3Why is the standard definition of cocycle the one that _always_ comes up?? 3Stable w-length 6What are CR manifolds like? 10Circle bundles over $RP^2$ 8What’s an example of a space that needs the Hahn-Banach Theorem? 3Lie Groups and Manifolds 28What should be offered in undergraduate mathematics that’s currently not (or isn’t usually)? 2What is an example of a function on M_g? 6Independence of the continuum hypothesis on ZFC 6Dolbeault cohomology 9Rational Group Cohomology 3Symmetrical Presentation of 4-Dimensional Rotation Matrix 4can you fool SnapPea? 2Minimal surface in a ball 8Algorithm generalizing continued fractions for non-quadratic algebraic numbers 17Is a subgroup of a free abelian group free abelian? 9What is the right way to think about / represent general tilings? 5What’s a non-abelian totally ordered group?