Powers of binary forms and derived Hermite reciprocity

Fuente: arXiv
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Auteurs principaux: Raicu, Claudiu, Sam, Steven V, Weyman, Jerzy, Yang, Fuxiang
Format: Preprint
Publié: 2026
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author Raicu, Claudiu
Sam, Steven V
Weyman, Jerzy
Yang, Fuxiang
author_facet Raicu, Claudiu
Sam, Steven V
Weyman, Jerzy
Yang, Fuxiang
contents For $a,b \ge 1$, Hilbert found in 1886 a collection of polynomial equations that cut out set-theoretically the variety X parametrizing a-th powers of binary forms of degree b. We determine the ideal of all polynomials vanishing on X, showing that it is generated in degree b+1 and that it has a linear minimal free resolution. We do this by generalizing results of Abdesselam and Chipalkatti on an analogue of the Foulkes--Howe map and by establishing a derived analogue of the classical Hermite reciprocity theorem for complexes of ${\rm SL}_2$-representations. In our investigation, we are led to the ideal generated by the subrepresentation ${\rm Sym}^{ab}({\Bbb C}^2) \subset {\rm Sym}^a({\rm Sym}^b {\Bbb C}^2)$. We determine its Castelnuovo--Mumford regularity in general and the minimal free resolution for small values of b.
format Preprint
id arxiv_https___arxiv_org_abs_2602_15175
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Powers of binary forms and derived Hermite reciprocity
Raicu, Claudiu
Sam, Steven V
Weyman, Jerzy
Yang, Fuxiang
Commutative Algebra
Algebraic Geometry
13D02
For $a,b \ge 1$, Hilbert found in 1886 a collection of polynomial equations that cut out set-theoretically the variety X parametrizing a-th powers of binary forms of degree b. We determine the ideal of all polynomials vanishing on X, showing that it is generated in degree b+1 and that it has a linear minimal free resolution. We do this by generalizing results of Abdesselam and Chipalkatti on an analogue of the Foulkes--Howe map and by establishing a derived analogue of the classical Hermite reciprocity theorem for complexes of ${\rm SL}_2$-representations. In our investigation, we are led to the ideal generated by the subrepresentation ${\rm Sym}^{ab}({\Bbb C}^2) \subset {\rm Sym}^a({\rm Sym}^b {\Bbb C}^2)$. We determine its Castelnuovo--Mumford regularity in general and the minimal free resolution for small values of b.
title Powers of binary forms and derived Hermite reciprocity
topic Commutative Algebra
Algebraic Geometry
13D02
url https://arxiv.org/abs/2602.15175