56 understanding Steenrod squares 2009-10-13T21:44:45.610

43 Can $N^2$ have only digits 0 and 1, other than $N=10^k$? 2009-09-29T00:20:06.940

23 How do you see the genus of a curve, just looking at its function field? 2009-10-06T22:02:56.257

18 Can you explicitly write $\mathbb{R}^2$ as a disjoint union of two totally path disconnected sets? 2009-10-06T22:06:19.480

17 Which sequences can be extended to analytic functions? (e. g., Ackermann's function) 2009-10-27T23:50:08.043

15 Cohomology and Eilenberg-MacLane spaces 2009-10-27T20:41:56.053

12 How should I approximate real numbers by algebraic ones? 2009-10-27T18:27:59.433

11 How much "Morse theory" can be accomplished given only a continuous transformation of a space? 2009-11-08T21:44:08.243

10 Can you describe the image of the exponential map B(H)->B(H). 2009-10-06T22:05:03.273

10 When does the sheaf direct image functor f_* have a right adjoint? 2009-10-27T19:58:07.950

8 When does the sequence of iterates of a rational function converge? 2009-10-06T22:05:32.477

8 What is an example of a topological space that is not homotopy equivalent to a CW-complex? 2009-10-18T21:36:34.523

7 Critical points on a fiber bundle 2009-10-06T04:45:11.800

7 Analogues of the Weierstrass p function for higher genus compact Riemann surfaces 2009-10-27T22:18:09.573

6 How can you find small denominators inside triangles? 2009-10-04T20:19:43.440

6 Is there a category in which finite limits and directed colimits *don't* commute 2009-10-06T22:04:16.100

6 Can I finitely color Z^2 such that (x,a) and (a,y) are different for every x,y,a? 2009-10-23T22:56:10.343

5 Characterizing the Radon transforms of log-concave functions 2009-10-13T21:08:59.743