BGU Seminar on Algebraic Combinatorics (Note unusual day of meeting ! ) Date: Thursday, April 21, 2011 Time: 12:10 - 14:00 Place: The Deichmann Building for Mathematics, room -101 Speaker: Alexandre Zvonkine University of Boredeaux 1, France Dept. of Computer Science Title: Belyi functions and "dessins d'enfants" Abstract Belyi function is a rational or a meromorphic function having only three ramification points; traditionally, these points are fixed as 0, 1, and infinity. The preimage of the segment [0,1] under a Belyi function is a combinatorial map, i.e., a graph embedded in (or drawn on) a 2-dimensional surface; it was Grothendieck who called these maps "dessins d'enfants", which means in French "children's drawings". The above construction permits to establish profound relations between combinatorics of maps, Riemann surfaces, Galois theory, permutation groups, and various other subjects. In the talk, we will give a general introduction to the subject, and then illustrate it by certain examples. ******************************************************************** Dr. Mikhail Klin Department of Mathematics Ben-Gurion University of the Negev P.O.Box 653, Beer Sheva 84105, Israel Tel: (0)8/6477-811 (office) (0)8/641-37-15 (home) Fax: +972-(0)8/6477-648 e-mail: <klin@cs.bgu.ac.il> --------------------------------------------------------- Technion Math Net-2 (TECHMATH2) Editor: Michael Cwikel <techm@math.technion.ac.il> Announcement from: Mikhail Klin <klin@cs.bgu.ac.il>