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Main Author: Kaygun, Atabey
Format: Preprint
Published: 2026
Subjects:
Online Access:https://arxiv.org/abs/2601.05715
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author Kaygun, Atabey
author_facet Kaygun, Atabey
contents We study quadratic moduli schemes $X$ of algebra laws on a fixed vector space $W$ under the transport-of-structure action of $GL(W)$ on $Hom(W^{\otimes 2},W)$. We construct an intrinsic three-term deformation complex on $X$ whose fibers encode transverse first-order classes and primary obstructions, and whose cohomology agrees on the operadic loci with the standard low-degree deformation cohomology (à la Gerstenhaber and Nijenhuis--Richardson). We then define a canonical quadratic map $κ^{inc}_{2,μ}\colon H^2_{inc}(μ)\to H^3_{inc}(μ)$ that controls second-order lifts modulo isotriviality. If $μ$ is smooth point in a reduced component and $(κ^{inc}_{2,μ})^{-1}(0)=\{0\}$, then the $G$-orbit of $μ$ is Zariski open in that component. This provides a coordinate-free explanation of Richardson-type geometric rigidity even when the second deformation cohomology does not vanish.
format Preprint
id arxiv_https___arxiv_org_abs_2601_05715
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Geometric Rigidity in Moduli Stacks of Algebras
Kaygun, Atabey
Algebraic Geometry
14D23 13D10
We study quadratic moduli schemes $X$ of algebra laws on a fixed vector space $W$ under the transport-of-structure action of $GL(W)$ on $Hom(W^{\otimes 2},W)$. We construct an intrinsic three-term deformation complex on $X$ whose fibers encode transverse first-order classes and primary obstructions, and whose cohomology agrees on the operadic loci with the standard low-degree deformation cohomology (à la Gerstenhaber and Nijenhuis--Richardson). We then define a canonical quadratic map $κ^{inc}_{2,μ}\colon H^2_{inc}(μ)\to H^3_{inc}(μ)$ that controls second-order lifts modulo isotriviality. If $μ$ is smooth point in a reduced component and $(κ^{inc}_{2,μ})^{-1}(0)=\{0\}$, then the $G$-orbit of $μ$ is Zariski open in that component. This provides a coordinate-free explanation of Richardson-type geometric rigidity even when the second deformation cohomology does not vanish.
title Geometric Rigidity in Moduli Stacks of Algebras
topic Algebraic Geometry
14D23 13D10
url https://arxiv.org/abs/2601.05715