English

A converse to geometric Manin's conjecture for general low degree hypersurfaces and Poincar\'e duality

Algebraic Geometry 2026-02-10 v2 Number Theory

Abstract

Geometric Manin's conjecture predicts that components of the moduli space of curves on a Fano variety parametrizing non-free curves are pathological and arise from "accumulating" morphisms that increase the Fujita invariant. By passing to positive characteristic and employing a higher genus generalization of the circle method, we prove a converse to this conjecture for general hypersurfaces XX in Pn\mathbb{P}^{n} of degree dn/4+3/2d\le n/4+3/2, namely that there are no such accumulating maps to XX. One consequence of this is a version of Poincar\'e duality for these moduli spaces in a range.

Keywords

Cite

@article{arxiv.2501.12506,
  title  = {A converse to geometric Manin's conjecture for general low degree hypersurfaces and Poincar\'e duality},
  author = {Matthew Hase-Liu},
  journal= {arXiv preprint arXiv:2501.12506},
  year   = {2026}
}

Comments

18 pages; fixed typos, improved exposition, and added an application