Welschinger--Witt invariants

Fuente: arXiv
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Main Authors: Brugallé, Erwan, Rau, Johannes, Wickelgren, Kirsten
Format: Preprint
Published: 2025
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author Brugallé, Erwan
Rau, Johannes
Wickelgren, Kirsten
author_facet Brugallé, Erwan
Rau, Johannes
Wickelgren, Kirsten
contents Welschinger invariants are signed counts of real rational curves satisfying contraints. Quadratic Gromov--Witten invariants give such counts over general fields of characteristic different from 2 and 3. For rational del Pezzo surfaces over a field, we propose a conjectural relationship between Welschinger and quadratic Gromov--Witten invariants. We construct multivariable unramified Witt invariants, in the sense of Serre, from Welschinger invariants and call them Welschinger--Witt invariants. We show that quadratic Gromov--Witten invariants are also Witt invariants and control their ramification. We then conjecture an equality between these Witt invariants, in particular giving a conjectural computation of all the quadratic Gromov--Witten invariants of $k$-rational surfaces. We prove this conjecture for $k$-rational del Pezzo surfaces of degree at least 6.
format Preprint
id arxiv_https___arxiv_org_abs_2509_04172
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Welschinger--Witt invariants
Brugallé, Erwan
Rau, Johannes
Wickelgren, Kirsten
Algebraic Geometry
K-Theory and Homology
Symplectic Geometry
Welschinger invariants are signed counts of real rational curves satisfying contraints. Quadratic Gromov--Witten invariants give such counts over general fields of characteristic different from 2 and 3. For rational del Pezzo surfaces over a field, we propose a conjectural relationship between Welschinger and quadratic Gromov--Witten invariants. We construct multivariable unramified Witt invariants, in the sense of Serre, from Welschinger invariants and call them Welschinger--Witt invariants. We show that quadratic Gromov--Witten invariants are also Witt invariants and control their ramification. We then conjecture an equality between these Witt invariants, in particular giving a conjectural computation of all the quadratic Gromov--Witten invariants of $k$-rational surfaces. We prove this conjecture for $k$-rational del Pezzo surfaces of degree at least 6.
title Welschinger--Witt invariants
topic Algebraic Geometry
K-Theory and Homology
Symplectic Geometry
url https://arxiv.org/abs/2509.04172