English

A counterexample to the parity conjecture

Algebraic Geometry 2024-02-06 v2 Commutative Algebra

Abstract

Let [Z]HilbdA3[Z]\in\text{Hilb}^d \mathbb A^3 be a zero-dimensional subscheme of the affine three-dimensional complex space of length d>0d>0. Okounkov and Pandharipande have conjectured that the dimension of the tangent space of HilbdA3\text{Hilb}^d \mathbb A^3 at [Z][Z] and dd have the same parity. The conjecture was proven by Maulik, Nekrasov, Okounkov and Pandharipande for points [Z][Z] defined by monomial ideals and very recently by Ramkumar and Sammartano for homogeneous ideals. In this paper we exhibit a family of zero-dimensional schemes in Hilb12A3\text{Hilb}^{12} \mathbb A^3, which disproves the conjecture in the general non-homogeneous case.

Cite

@article{arxiv.2305.18191,
  title  = {A counterexample to the parity conjecture},
  author = {Franco Giovenzana and Luca Giovenzana and Michele Graffeo and Paolo Lella},
  journal= {arXiv preprint arXiv:2305.18191},
  year   = {2024}
}

Comments

13 pages. Final version

R2 v1 2026-06-28T10:49:24.206Z