Generic Multiplicities of Hilbert Schemes on Thickened Lines

Let T_(n,beta) be the Hilbert scheme of n points on the thickened line defined by y^beta=0 over C. For the component indexed by a partition lambda of n with largest part at most beta, we compute its ambient generic multiplicity as the product of binomial(beta,lambda_i). The proof uses disjoint-support factorization and a cyclic chart in which a monic polynomial divides t^beta; the remainder equations form a weighted complete intersection. In particular, a chart of T_(2,3) has generic local ring K[u]/(u^3), whereas imposing a repeated-root discriminant produces K[u]/(u^2). This distinguishes ambient multiplicity from the multiplicity of a support stratum. We compare with the known multinomial multiplicity of the characteristic-polynomial nilpotent fiber, and describe reduced Jordan strata and their closure obstruction. The stated geometric theorem is complete; the broad AIM categorical cell question remains unresolved. This preprint is unrefereed and makes no absolute-priority or formal-verification claim.

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Publication Details

Journal
Zenodo (CERN European Organization for Nuclear Research)
Published
2026-10-14
DOI
https://doi.org/10.5281/zenodo.23377435
Primary Topic
Algebraic Geometry and Number Theory
Type
preprint
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preprint

Generic Multiplicities of Hilbert Schemes on Thickened Lines

Alper Ferudun
Zenodo (CERN European Organization for Nuclear Research)
Algebraic Geometry and Number Theory
preprint

Generic Multiplicities of Hilbert Schemes on Thickened Lines

Alper Ferudun
preprint en

Abstract

Let T_(n,beta) be the Hilbert scheme of n points on the thickened line defined by y^beta=0 over C. For the component indexed by a partition lambda of n with largest part at most beta, we compute its ambient generic multiplicity as the product of binomial(beta,lambda_i). The proof uses disjoint-support factorization and a cyclic chart in which a monic polynomial divides t^beta; the remainder equations form a weighted complete intersection. In particular, a chart of T_(2,3) has generic local ring K[u]/(u^3), whereas imposing a repeated-root discriminant produces K[u]/(u^2). This distinguishes ambient multiplicity from the multiplicity of a support stratum. We compare with the known multinomial multiplicity of the characteristic-polynomial nilpotent fiber, and describe reduced Jordan strata and their closure obstruction. The stated geometric theorem is complete; the broad AIM categorical cell question remains unresolved. This preprint is unrefereed and makes no absolute-priority or formal-verification claim.

Zenodo (CERN European Organization for Nuclear Research)
Algebraic Geometry and Number Theory
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