Mathematics Colloquium: Andrew Goh
Topic: k-Pop Stack Sorting
In 1981 Avis and Newborn characterised permutations sorted by 1-pass pop stack, initiating the study of pop stack sorting. Pudwell and Smith characterised permutations sorted by 2-pass pop stack, in terms of avoiding a finite set of patterns of a certain type, and enumerated them by giving a bijection to a special family of polynominoes. Claesson and Guomundsson then gave a general enumeration formula for k passes.
In this talk, I will explain about 3-pass pop stack as well as some general results for k-pass pop stack.