Liminal reciprocity and factorization statistics

Abstract

Let $M_{d,n}(q)$ denote the number of monic irreducible polynomials in ${\mathbb{F}}_q[x_1,x_2,\dots ,x_n]$ of degree $d$. We show that for a fixed degree $d$, the sequence $M_{d,n}(q)$ converges $q$-adically to an explicitly determined rational function $M_{d,\infty }(q)$. Furthermore we show that the limit $M_{d,\infty }(q)$ is related to the classic necklace polynomial $M_{d,1}(q)$ by an involutive functional equation, leading to a phenomenon we call liminal reciprocity. The limiting first moments of factorization statistics for squarefree polynomials are expressed in terms of a family of symmetric group representations as a consequence of liminal reciprocity.

22 pages. To appear in Algebraic Combinatorics