Chevalley Polytopes and Newton-Okounkov Bodies

Fuente: arXiv
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Autori principali: Spacek, Peter, Wang, Charles
Natura: Preprint
Pubblicazione: 2024
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author Spacek, Peter
Wang, Charles
author_facet Spacek, Peter
Wang, Charles
contents We construct a family of polytopes, which we call Chevalley polytopes, associated to homogeneous spaces $X=G/P$ in their projective embeddings $X\hookrightarrow \mathbb{P}(V_{\varpi})$ together with a choice of reduced expression for the minimal coset representative $w^P$ of $w_0$ in $W/W_P$. When $X$ is minuscule in its minimal embedding, we describe our construction in terms of order polytopes of minuscule posets and use the associated combinatorics to show that minuscule Chevalley polytopes are Newton-Okounkov bodies for $X$ and that the Plücker coordinates on $X$ form a Khovanskii basis for $\mathbb{C}[X]$. We conjecture similar properties for general $X$ and general embeddings $X\hookrightarrow\mathbb{P}(V_\varpi)$, along with a remarkable decomposition property which we consider as a polytopal shadow of the Littlewood-Richardson rule. We highlight a connection between Chevalley polytopes and string polytopes and give examples where Chevalley polytopes possess better combinatorial properties than string polytopes. We conclude with several examples further illustrating and supporting our conjectures.
format Preprint
id arxiv_https___arxiv_org_abs_2411_10276
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Chevalley Polytopes and Newton-Okounkov Bodies
Spacek, Peter
Wang, Charles
Algebraic Geometry
Combinatorics
14M25, 14M17, 52B20, 06A07, 05E14, 20G20
We construct a family of polytopes, which we call Chevalley polytopes, associated to homogeneous spaces $X=G/P$ in their projective embeddings $X\hookrightarrow \mathbb{P}(V_{\varpi})$ together with a choice of reduced expression for the minimal coset representative $w^P$ of $w_0$ in $W/W_P$. When $X$ is minuscule in its minimal embedding, we describe our construction in terms of order polytopes of minuscule posets and use the associated combinatorics to show that minuscule Chevalley polytopes are Newton-Okounkov bodies for $X$ and that the Plücker coordinates on $X$ form a Khovanskii basis for $\mathbb{C}[X]$. We conjecture similar properties for general $X$ and general embeddings $X\hookrightarrow\mathbb{P}(V_\varpi)$, along with a remarkable decomposition property which we consider as a polytopal shadow of the Littlewood-Richardson rule. We highlight a connection between Chevalley polytopes and string polytopes and give examples where Chevalley polytopes possess better combinatorial properties than string polytopes. We conclude with several examples further illustrating and supporting our conjectures.
title Chevalley Polytopes and Newton-Okounkov Bodies
topic Algebraic Geometry
Combinatorics
14M25, 14M17, 52B20, 06A07, 05E14, 20G20
url https://arxiv.org/abs/2411.10276