Regular subdivisions, bounds on initial ideals, and categorical limits

Fuente: arXiv
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Auteurs principaux: Balla, George, Corey, Daniel, Makhlin, Igor, Schleis, Victoria
Format: Preprint
Publié: 2024
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author Balla, George
Corey, Daniel
Makhlin, Igor
Schleis, Victoria
author_facet Balla, George
Corey, Daniel
Makhlin, Igor
Schleis, Victoria
contents Several known constructions relate initial degenerations of projective toric varieties and Grassmannians to regular subdivisions of appropriate point configurations. We define a general framework which allows for partial generalizations of these constructions to arbitrary projective schemes (as well as their very affine parts). We associate a point configuration $A$ with any homogeneous ideal $I$. We obtain upper and lower bounds on every initial ideal of $I$, defining them in terms of the regular subdivision of $A$ given by the same weight. Furthermore, both bounds are interpreted categorically via (co)limits over the face poset of the subdivision. We also investigate when these bounds are exact, showing that the respective weights form a subfan in the secondary fan of $A$.
format Preprint
id arxiv_https___arxiv_org_abs_2411_12819
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Regular subdivisions, bounds on initial ideals, and categorical limits
Balla, George
Corey, Daniel
Makhlin, Igor
Schleis, Victoria
Combinatorics
Algebraic Geometry
Several known constructions relate initial degenerations of projective toric varieties and Grassmannians to regular subdivisions of appropriate point configurations. We define a general framework which allows for partial generalizations of these constructions to arbitrary projective schemes (as well as their very affine parts). We associate a point configuration $A$ with any homogeneous ideal $I$. We obtain upper and lower bounds on every initial ideal of $I$, defining them in terms of the regular subdivision of $A$ given by the same weight. Furthermore, both bounds are interpreted categorically via (co)limits over the face poset of the subdivision. We also investigate when these bounds are exact, showing that the respective weights form a subfan in the secondary fan of $A$.
title Regular subdivisions, bounds on initial ideals, and categorical limits
topic Combinatorics
Algebraic Geometry
url https://arxiv.org/abs/2411.12819