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Let $B$ be a smooth projective curve and let $\pi: \mathcal{X} \to B$ be a smooth integral model of a geometrically integral Fano variety over $K(B)$. Geometric Manin's Conjecture predicts the structure of the irreducible components $M…

Algebraic Geometry · Mathematics 2025-04-01 Brian Lehmann , Eric Riedl , Sho Tanimoto

Let $X$ be a smooth projective Fano variety over the complex numbers. We study the moduli spaces of rational curves on $X$ using the perspective of Manin's Conjecture. In particular, we bound the dimension and number of components of spaces…

Algebraic Geometry · Mathematics 2019-04-17 Brian Lehmann , Sho Tanimoto

We classify families of free rational curves on all smooth Fano threefolds over the complex numbers. In particular, we prove the family of very free rational curves representing any fixed numerical curve class is either irreducible or…

Algebraic Geometry · Mathematics 2024-09-04 Andrew Burke , Eric Jovinelly

We prove several classification results for the components of the moduli space of rational curves on a smooth Fano threefold. In particular, we prove a conjecture of Batyrev on the growth of the number of components as the degree increases.…

Algebraic Geometry · Mathematics 2022-07-12 Roya Beheshti , Brian Lehmann , Eric Riedl , Sho Tanimoto

We describe the irreducible components of the moduli spaces of rational curves on Artin-Mumford double solids. This provides the first example of Fano varieties that satisfy Geometric Manin's Conjecture with multiple Manin components in…

Algebraic Geometry · Mathematics 2025-01-17 Fumiya Okamura

Geometric Manin's conjecture for complex Fano varieties describes the structure of the moduli space of curves. We propose a version of this conjecture in characteristic $p$ and describe its connection to the Batyrev--Manin--Peyre--Tschinkel…

Algebraic Geometry · Mathematics 2026-01-15 Brian Lehmann , Sho Tanimoto

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…

Algebraic Geometry · Mathematics 2026-02-10 Matthew Hase-Liu

We prove a structural result for geometrically non-reduced varieties and give applications to Fano varieties. For example, we show that if $X$ is the generic fibre of a Mori fibre space of relative dimension $n$, and the characteristic is…

Algebraic Geometry · Mathematics 2023-01-06 Lena Ji , Joe Waldron

Let $X$ be a smooth cubic threefold. By invoking ideas from Geometric Manin's Conjecture, we give a complete description of the main components of the Kontsevich moduli space of genus one stable maps $\overline{M}_{1,0}(X)$. In particular,…

Algebraic Geometry · Mathematics 2026-05-12 Enhao Feng

We study the moduli spaces of rational curves on prime Fano threefolds of index 1. For general threefolds of most genera we compute the dimension and the number of irreducible components of these moduli spaces. Our results confirm Geometric…

Algebraic Geometry · Mathematics 2019-08-26 Brian Lehmann , Sho Tanimoto

Let $X_\mathcal{A}$ be the projective toric variety corresponding to a finite set of lattice points $\mathcal{A}$. We show that irreducible components of the Fano scheme $\mathbf{F}_k(X_\mathcal{A})$ parametrizing $k$-dimensional linear…

Algebraic Geometry · Mathematics 2019-11-26 Nathan Ilten , Alexandre Zotine

We study the spaces of rational curves on Fano threefolds with Gorenstein terminal singularities. We generalize the results regarding Geometric Manin's Conjecture for smooth Fano threefolds, including the classification of subvarieties with…

Algebraic Geometry · Mathematics 2025-05-23 Fumiya Okamura

We describe the moduli space of rational curves on smooth Fano varieties of coindex 3. For varieties of dimension 5 or greater, we prove the moduli space has a single irreducible component for each effective numerical class of curves. For…

Algebraic Geometry · Mathematics 2024-09-04 Eric Jovinelly , Fumiya Okamura

Suppose that $X$ is a smooth projective variety and that $C$ is a general member of a family of free rational curves on $X$. We prove several statements showing that the Harder-Narasimhan filtration of $T_{X}|_{C}$ is approximately the same…

Algebraic Geometry · Mathematics 2021-04-09 Brian Lehmann , Eric Riedl

Let V be a plane smooth cubic curve over a finitely generated field k. The Mordell-Weil theorem for V states that there is a finite subset P \subset V(k) such that the whole V(k) can be obtained from P by drawing secants and tangents…

Algebraic Geometry · Mathematics 2008-02-07 Bogdan G. Vioreanu

We use Gromov-Witten theory to study rational curves in holomorphic symplectic varieties. We present a numerical criterion for the existence of uniruled divisors swept out by rational curves in the primitive curve class of a very general…

Algebraic Geometry · Mathematics 2020-05-01 Georg Oberdieck , Junliang Shen , Qizheng Yin

We study a geometric version of the dimension growth conjecture. While it is closely related in spirit to themes arising in geometric Manin's conjecture, it applies in greater generality and provides more uniform bounds. For an irreducible…

Number Theory · Mathematics 2026-04-09 Tijs Buggenhout , Yotam I. Hendel , Floris Vermeulen

The Manin-Peyre conjecture is established for smooth spherical Fano threefolds of semisimple rank one and type N. Together with the previously solved case T and the toric cases, this covers all types of smooth spherical Fano threefolds. The…

Number Theory · Mathematics 2024-06-14 Valentin Blomer , Jörg Brüdern , Ulrich Derenthal , Giuliano Gagliardi

We extend some results of [BF12] on subfactor projections to show that the projection of a free factor B to the free factor complex of the free factor A is well-defined with uniformly bound diameter, unless either A is contained in B or A…

Geometric Topology · Mathematics 2016-01-20 Samuel J. Taylor

We study the geometry of the Fano schemes $\mathrm{\textbf{F}}_{k}(\mathrm{SD}_n^r)$ of the projective variety $\mathrm{SD}_n^r$ defined by the $r\times r$ minors of a symmetric $n\times n$ matrix filled with indeterminates. These schemes…

Algebraic Geometry · Mathematics 2023-10-12 Ahmad Mokhtar
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