On Blecher and Knopfmacher's Fixed Points for Integer Partitions

Abstract

Recently, Blecher and Knopfmacher explored the notion of fixed points in integer partitions and hypothesized on the relative number of partitions with and without a fixed point. We resolve their open question by working fixed points into a growing number of interconnected partition statistics involving Frobenius symbols, Dyson's crank, and the mex (minimal excluded part). Also, we generalize the definition of fixed points and connect that expanded notion to the $\text{mex}_j$ defined by Hopkins, Sellers, and Stanton as well as the $j$-Durfee rectangle defined by Hopkins, Sellers, and Yee.