Inversion polynomials for 321-avoiding permutations: addendum

TL;DR

This paper presents additional results on inversion number and major index polynomials for 321-avoiding permutations, focusing on properties like symmetry, unimodality, and signed enumeration, complementing previous work.

Contribution

It provides new insights into the combinatorial properties of inversion and major index polynomials for 321-avoiding permutations, specifically addressing symmetry, unimodality, and modulo 2 behavior.

Findings

Analysis of symmetry and unimodality of polynomials

Results on behavior modulo 2

Signed enumeration outcomes

Abstract

This addendum contains results about the inversion number and major index polynomials for permutations avoiding 321 which did not fit well into the original paper. In particular, we consider symmetry, unimodality, behavior modulo 2, and signed enumeration.