Algebra and Combinatorics Seminar

Date: March 6, 2020

Time: 3:00PM - 3:50PM

Location: BLOC 628

Speaker: Catherine Yan, Texas A&M University

Title: Counting Rational Parking Functions

Abstract: Let $a,b$ be a pair of co-prime positive integers. An (a,b)-rational parking function is a sequence (x_1, x_2, ..., x_b) of non-negative integers such that x_{(i)} is less than or equal to ia/b for all i, where x_{(i)} is the i-th smallest term of x_1, x_2, ..., x_b. Rational parking functions are important in the study of rational Catalan combinatorics and representation theory of MacDonald polynomials. In this talk we consider rational parking functions of length n, where n is a multiple of b, and present a counting formula for the number of rational parking functions. The techniques are basic combinatorial tools, including lattice path counting, the cycle lemma, and the inclusion-exclusion principle. This is based on a joint work with Yue Cai.