============================== Bar-Ilan Combinatorics Seminar ============================== The next meeting of the seminar this year will take place, IYH, on (when) Tuesday, 3 Kislev (Nov. 13) refreshments at 11:45, talk at 12:00 noon (where) Room 331 (Math Dept Seminar Room), Math and CS Building (216), Bar-Ilan University (who) Eli Bagno (Jerusalem College of Technology) will talk about (what) "The Excedance of colored permutation groups: recursion, symmetry and excedance sets" Abstract: --------- The excedance number defined for the symmetric group S_n is well known to have an Eulerian distribution. Nevertheless, the classical proof uses the descent number rather than proving it directly from the definitions. We present a direct proof based on recursion which seems to be folklore, and extend it to the group of colored permutations G_{r,n}. We also show that the generating function of the excedance number defined on G_{r,n} is symmetric. In the second part of the talk we define the excedence set and the excedance word on G_{r,n} and use the inclusion - exclusion principle to calculate the number of colored permutations having a prescribed excedance word. If time permits, we show some symmetric properties as Log concavity and unimodality of a specific sequence of excedance words. (Joint work with David Garber and Robert Shwartz) Forthcoming Events ================== * 10 Kislev (Nov. 20) Ron Holzman (Technion): "On the independence numbers of the cubes of odd cycles" * 17 Kislev (Nov. 27) Zur Izhakian (Bar-Ilan University and Univ. Paris 6): "Extended tropical algebra - basic notions" ************************************************************************* You are all invited ! (Graduate students especially welcome) If you want to give a talk at the seminar, or know a prospective speaker, please contact Ron Adin . Seminar's homepage: see *************************************************************************