# Character polynomials for two rows and hook partitions

## TL;DR

This paper introduces combinatorial class functions related to Young diagram tilings, providing new uniform expressions and relations that lead to proofs of identities for Kronecker coefficients of specific partitions.

## Contribution

It develops a new combinatorial framework for class functions on symmetric groups and proves identities linking these functions to Kronecker coefficients for hook and two-row partitions.

## Key findings

- Established a relation between combinatorial class functions in the character ring.
- Proved Goupil's generating function identity.
- Derived Rosas' formula for Kronecker coefficients of hook and two-row partitions.

## Abstract

Representation theory of the symmetric group $\mathfrak{S}_n$ has a very distinctive combinatorial flavor. The conjugacy classes as well as the irreducible characters are indexed by integer partitions $\lambda \vdash n$. We introduce class functions on $\mathfrak{S}_n$ that count the number of certain tilings of Young diagrams. The counting interpretation gives a uniform expression of these class functions in the ring of character polynomials, as defined by \cite{murnaghanfirst}. A modern treatment of character polynomials is given in \cite{orellana-zabrocki}. We prove a relation between these combinatorial class functions in the (virtual) character ring. From this relation, we were able to prove Goupil's generating function identity \cite{goupil}, which can then be used to derive Rosas' formula \cite{rosas} for Kronecker coefficients of hook shape partitions and two row partitions.