Algebraic invariants of the special fiber ring of ladder determinantal modules

Fuente: arXiv
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Autori principali: Costantini, Alessandra, Fouli, Louiza, Goel, Kriti, Lin, Kuei-Nuan, Lindo, Haydee, Liske, Whitney, Mostafazadehfard, Maral
Natura: Preprint
Pubblicazione: 2025
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author Costantini, Alessandra
Fouli, Louiza
Goel, Kriti
Lin, Kuei-Nuan
Lindo, Haydee
Liske, Whitney
Mostafazadehfard, Maral
author_facet Costantini, Alessandra
Fouli, Louiza
Goel, Kriti
Lin, Kuei-Nuan
Lindo, Haydee
Liske, Whitney
Mostafazadehfard, Maral
contents We provide explicit formulas for key invariants of special fiber rings of ladder determinantal modules, that is, modules that are direct sums of ideals of maximal minors of a ladder matrix. Our results are given in terms of the combinatorial data of the associated ladder matrix. In particular, we compute its dimension, regularity, $a$-invariant, and multiplicity, which via \textsc{Sagbi} degeneration coincide with those of Hibi rings associated to a distributive lattice. Then, via Gröbner degeneration these calculations are reduced to quotients of polynomial rings by monomial ideals. Our formula for the multiplicity of the special fiber ring of these ladder determinantal modules is obtained by counting the number of standard skew Young tableaux associated to a certain skew partition, and so provides a natural generalization of the classical formula for the degree of the Grassmannian.
format Preprint
id arxiv_https___arxiv_org_abs_2507_22167
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Algebraic invariants of the special fiber ring of ladder determinantal modules
Costantini, Alessandra
Fouli, Louiza
Goel, Kriti
Lin, Kuei-Nuan
Lindo, Haydee
Liske, Whitney
Mostafazadehfard, Maral
Commutative Algebra
Primary 13A30, 13C40, 13F65, Secondary 14M12, 13F50, 05E40
We provide explicit formulas for key invariants of special fiber rings of ladder determinantal modules, that is, modules that are direct sums of ideals of maximal minors of a ladder matrix. Our results are given in terms of the combinatorial data of the associated ladder matrix. In particular, we compute its dimension, regularity, $a$-invariant, and multiplicity, which via \textsc{Sagbi} degeneration coincide with those of Hibi rings associated to a distributive lattice. Then, via Gröbner degeneration these calculations are reduced to quotients of polynomial rings by monomial ideals. Our formula for the multiplicity of the special fiber ring of these ladder determinantal modules is obtained by counting the number of standard skew Young tableaux associated to a certain skew partition, and so provides a natural generalization of the classical formula for the degree of the Grassmannian.
title Algebraic invariants of the special fiber ring of ladder determinantal modules
topic Commutative Algebra
Primary 13A30, 13C40, 13F65, Secondary 14M12, 13F50, 05E40
url https://arxiv.org/abs/2507.22167