Interlacing triangles, Schubert puzzles, and graph colorings

Fuente: arXiv
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Autori principali: Gaetz, Christian, Gao, Yibo
Natura: Preprint
Pubblicazione: 2024
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author Gaetz, Christian
Gao, Yibo
author_facet Gaetz, Christian
Gao, Yibo
contents We show that interlacing triangular arrays, introduced by Aggarwal-Borodin-Wheeler to study certain probability measures, can be used to compute structure constants for multiplying Schubert classes in the $K$-theory of Grassmannians, in the cohomology of their cotangent bundles, and in the cohomology of partial flag varieties. Our results are achieved by establishing a splitting lemma, allowing for interlacing triangular arrays of high rank to be decomposed into arrays of lower rank, and by constructing a bijection between interlacing triangular arrays of rank 3 with certain proper vertex colorings of the triangular grid graph that factors through generalizations of Knutson-Tao puzzles. Along the way, we prove one enumerative conjecture of Aggarwal-Borodin-Wheeler and disprove another.
format Preprint
id arxiv_https___arxiv_org_abs_2408_07863
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Interlacing triangles, Schubert puzzles, and graph colorings
Gaetz, Christian
Gao, Yibo
Combinatorics
Algebraic Geometry
Probability
We show that interlacing triangular arrays, introduced by Aggarwal-Borodin-Wheeler to study certain probability measures, can be used to compute structure constants for multiplying Schubert classes in the $K$-theory of Grassmannians, in the cohomology of their cotangent bundles, and in the cohomology of partial flag varieties. Our results are achieved by establishing a splitting lemma, allowing for interlacing triangular arrays of high rank to be decomposed into arrays of lower rank, and by constructing a bijection between interlacing triangular arrays of rank 3 with certain proper vertex colorings of the triangular grid graph that factors through generalizations of Knutson-Tao puzzles. Along the way, we prove one enumerative conjecture of Aggarwal-Borodin-Wheeler and disprove another.
title Interlacing triangles, Schubert puzzles, and graph colorings
topic Combinatorics
Algebraic Geometry
Probability
url https://arxiv.org/abs/2408.07863