Video Lectures

We show that if G=?S|E? is a discrete group with Property (T) then E, as a system of equations over S, is not stable (under a mild condition). That is, E has approximate solutions in symmetric groups Sym(n), n?1, that are far from every solution in...

You can make a paper Moebius band by starting with a 1 by L rectangle, giving it a twist, and then gluing the ends together. The question is: How short can you make L and still succeed in making the thing? This question goes back to B. Halpern and C...