Tel Aviv University Colloquium 
Hello everyone,
The next colloquium talk will be held on Monday, 7/3/2011, 12:15, Schreiber
006, Tel Aviv University. The speaker is
     Sergei Tabachnikov (Pennsylvania State University)
and the title of his talk is
     Geometry, algebra, and dynamics of the pentagram map
The abstract is given below. Tea and coffee at 12:00, same room.
Hope to see you there. For information about future colloquiua, see
You are all welcome to suggest colloquium speakers, especially for the next
academic year.
Abstract: Introduced by R. Schwartz almost 20 years ago, the pentagram map
acts on plane n-gons, considered up to projective equivalence, by drawing
the diagonals that connect second-nearest vertices and taking the new n-gon
formed by their intersections. I shall survey recent work on the pentagram
map, in particular, I shall demonstrate that the dynamics of the pentagram
map is very regular: the map is completely integrable. I shall show that the
pentagram map is a discretization of the Boussinesq equation, a well known
completely integrable partial differential equation. An unexpected relation
between the spaces of polygons and combinatorial objects called the 2-frieze
patterns (generalizing the frieze patterns of Coxeter) will be revealed.
Eight new configuration theorems of projective geometry will be
demonstrated. The talk will be illustrated by computer animation.
Technion Math Net-2 (TECHMATH2)
Editor: Michael Cwikel   <> 
Announcement from: Bo'az Klartag   <>