Diagonal operators, $q$-Whittaker functions and rook theory

Fuente: arXiv
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Main Authors: Ram, Samrith, Schlosser, Michael J.
Format: Preprint
Published: 2023
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author Ram, Samrith
Schlosser, Michael J.
author_facet Ram, Samrith
Schlosser, Michael J.
contents We discuss the problem posed by Bender, Coley, Robbins and Rumsey of enumerating the number of subspaces which have a given profile with respect to a linear operator over the finite field $\mathbb{F}_q$. We solve this problem in the case where the operator is diagonalizable. The solution leads us to a new class of polynomials $b_{μν}(q)$ indexed by pairs of integer partitions. These polynomials have several interesting specializations and can be expressed as positive sums over semistandard tableaux. We present a new correspondence between set partitions and semistandard tableaux. A close analysis of this correspondence reveals the existence of several new set partition statistics which generate the polynomials $b_{μν}(q)$; each such statistic arises from a Mahonian statistic on multiset permutations. The polynomials $b_{μν}(q)$ are also given a description in terms of coefficients in the monomial expansion of $q$-Whittaker symmetric functions which are specializations of Macdonald polynomials. We express the Touchard--Riordan generating polynomial for chord diagrams by number of crossings in terms of $q$-Whittaker functions. We also introduce a class of $q$-Stirling numbers defined in terms of the polynomials $b_{μν}(q)$ and present connections with $q$-rook theory in the spirit of Garsia and Remmel.
format Preprint
id arxiv_https___arxiv_org_abs_2309_06401
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Diagonal operators, $q$-Whittaker functions and rook theory
Ram, Samrith
Schlosser, Michael J.
Combinatorics
15B33, 05A15, 05A18, 05A05, 05E05, 11B65
We discuss the problem posed by Bender, Coley, Robbins and Rumsey of enumerating the number of subspaces which have a given profile with respect to a linear operator over the finite field $\mathbb{F}_q$. We solve this problem in the case where the operator is diagonalizable. The solution leads us to a new class of polynomials $b_{μν}(q)$ indexed by pairs of integer partitions. These polynomials have several interesting specializations and can be expressed as positive sums over semistandard tableaux. We present a new correspondence between set partitions and semistandard tableaux. A close analysis of this correspondence reveals the existence of several new set partition statistics which generate the polynomials $b_{μν}(q)$; each such statistic arises from a Mahonian statistic on multiset permutations. The polynomials $b_{μν}(q)$ are also given a description in terms of coefficients in the monomial expansion of $q$-Whittaker symmetric functions which are specializations of Macdonald polynomials. We express the Touchard--Riordan generating polynomial for chord diagrams by number of crossings in terms of $q$-Whittaker functions. We also introduce a class of $q$-Stirling numbers defined in terms of the polynomials $b_{μν}(q)$ and present connections with $q$-rook theory in the spirit of Garsia and Remmel.
title Diagonal operators, $q$-Whittaker functions and rook theory
topic Combinatorics
15B33, 05A15, 05A18, 05A05, 05E05, 11B65
url https://arxiv.org/abs/2309.06401