Tel Aviv University Colloquium Hello everyone, The next colloquium talk will be held on: Monday, 22/10/2012, 12:15, Schreiber 006, Tel Aviv University. Speaker: Michael Polyak (Technion) Title: Knot and 3-manifold invariants via counting graphs and surfaces The abstract is given below. Tea and coffee at 12:00, same room. Hope to see you there. For information about future colloqiua, see <http://www.math.tau.ac.il/~ostrover/colloquium/colloq2012.html> Yours, Yaron -------------- Abstract: I will start with a short overview of the so-called perturbative invariants of links and 3-manifolds. While these invariants were intensively studied in the last two decades, many questions, inconsistencies and problems persist. The reason is that the construction is based on some complicated Feynman integrals in the perturbative Chern-Simons theory and a lot of technicalities are involved. In the main part of the talk I will describe an alternative elementary combinatorial construction of these invariants. It involves counting similar trivalent graphs in a link diagram. This approach immediately extends to invariants of 3-manifolds. Our construction can be restated in terms of counting certain surfaces ending on a link diagram. The latter description seem to be a combinatorial counterpart of a so-called "large N duality conjecture" by Gupakomar-Vafa, relating Chern-Simons theory to open strings. --------------------------------------------------------- Technion Math Net-2 (TECHMATH2) Editor: Michael Cwikel <techm@math.technion.ac.il> Announcement from: <ostrover@post.tau.ac.il>