Combinatorics Seminar - Fall 2014
Room 209, Goldsmith building
The Combinatorics Seminar is an introductory seminar for combinatorics. The talk should be accesible to first year graduate students.
Tuesday September 30
Speaker: Yan Zhuang
Title: Counting Permutations by Alternating Descents
Abstract: We find the exponential generating function for permutations with all valleys even and all peaks odd, and use it to determine the asymptotics for its coefficients, answering a question posed by Liviu Nicolaescu. We give two proofs for the generating function. The first proof uses a system of differential equations whose solution gives the generating function. For the second proof, we develop a new method for counting permutations by alternating descents using noncommutative symmetric functions. This is joint work with Ira Gessel.
Tuesday October 7
Tuesday October 14