Two Littlewood identities for fully inhomogeneous spin Hall-Littlewood symmetric rational functions

Fuente: arXiv
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Main Authors: Fischer, Ilse, Gangl, Moritz
Format: Preprint
Published: 2026
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_version_ 1866917375123652608
author Fischer, Ilse
Gangl, Moritz
author_facet Fischer, Ilse
Gangl, Moritz
contents Fully inhomogeneous spin Hall-Littlewood symmetric rational functions $F_λ$ arise as partition functions of certain path configurations in the $\mathfrak{sl}_2$ higher spin six vertex models. They are multiparameter generalizations of the classical Hall-Littlewood symmetric polynomials. We establish two new generalizations of the classical Littlewood identity, where we express a weighted sum of $F_λ$'s over all partitions $λ$ as a product of the Littlewood kernel and another simple product in one case, and a product of the Littlewood kernel and a Pfaffian in the other case. As a corollary we obtain a novel Littlewood identity for Hall-Littlewood symmetric polynomials. We also elaborate on the newly established connection between the fully inhomogeneous spin Hall-Littlewood symmetric rational functions $F_λ$ and the modified Robbins polynomials, the latter being multivariate generating functions for alternating sign matrices. This connection allowed us to discover the two generalizations of the Littlewood identity and we provide a bijection between the underlying combinatorial models in the case where $λ$ is strictly decreasing.
format Preprint
id arxiv_https___arxiv_org_abs_2603_29836
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Two Littlewood identities for fully inhomogeneous spin Hall-Littlewood symmetric rational functions
Fischer, Ilse
Gangl, Moritz
Combinatorics
05E05, 05A15, 82B23, 81R50
Fully inhomogeneous spin Hall-Littlewood symmetric rational functions $F_λ$ arise as partition functions of certain path configurations in the $\mathfrak{sl}_2$ higher spin six vertex models. They are multiparameter generalizations of the classical Hall-Littlewood symmetric polynomials. We establish two new generalizations of the classical Littlewood identity, where we express a weighted sum of $F_λ$'s over all partitions $λ$ as a product of the Littlewood kernel and another simple product in one case, and a product of the Littlewood kernel and a Pfaffian in the other case. As a corollary we obtain a novel Littlewood identity for Hall-Littlewood symmetric polynomials. We also elaborate on the newly established connection between the fully inhomogeneous spin Hall-Littlewood symmetric rational functions $F_λ$ and the modified Robbins polynomials, the latter being multivariate generating functions for alternating sign matrices. This connection allowed us to discover the two generalizations of the Littlewood identity and we provide a bijection between the underlying combinatorial models in the case where $λ$ is strictly decreasing.
title Two Littlewood identities for fully inhomogeneous spin Hall-Littlewood symmetric rational functions
topic Combinatorics
05E05, 05A15, 82B23, 81R50
url https://arxiv.org/abs/2603.29836