Refined lattice point counting on the moduli space of Klein surfaces

Fuente: arXiv
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Auteurs principaux: Chidambaram, Nitin Kumar, Garcia-Failde, Elba, Giacchetto, Alessandro, Osuga, Kento
Format: Preprint
Publié: 2026
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author Chidambaram, Nitin Kumar
Garcia-Failde, Elba
Giacchetto, Alessandro
Osuga, Kento
author_facet Chidambaram, Nitin Kumar
Garcia-Failde, Elba
Giacchetto, Alessandro
Osuga, Kento
contents We introduce the moduli space of metric Möbius graphs, which extend ribbon graphs to the non-orientable world. This space contains both the moduli space of Riemann surfaces and the moduli space of non-orientable Klein surfaces. Each metric Möbius graph is equipped with a measure of non-orientability. We count lattice points in this moduli space, weighted by the measure of non-orientability, and prove a refined version of Norbury's recursion for this count. Taking the limit as the mesh becomes finer, we deduce a recursion for the Euclidean volumes, yielding a refined version of the Witten--Kontsevich recursion. As an application, we give a geometric definition of the refined Euler characteristic of the moduli space and compute it explicitly, thereby answering a question of Goulden, Harer, and Jackson.
format Preprint
id arxiv_https___arxiv_org_abs_2605_09526
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Refined lattice point counting on the moduli space of Klein surfaces
Chidambaram, Nitin Kumar
Garcia-Failde, Elba
Giacchetto, Alessandro
Osuga, Kento
Algebraic Geometry
Mathematical Physics
Combinatorics
Geometric Topology
We introduce the moduli space of metric Möbius graphs, which extend ribbon graphs to the non-orientable world. This space contains both the moduli space of Riemann surfaces and the moduli space of non-orientable Klein surfaces. Each metric Möbius graph is equipped with a measure of non-orientability. We count lattice points in this moduli space, weighted by the measure of non-orientability, and prove a refined version of Norbury's recursion for this count. Taking the limit as the mesh becomes finer, we deduce a recursion for the Euclidean volumes, yielding a refined version of the Witten--Kontsevich recursion. As an application, we give a geometric definition of the refined Euler characteristic of the moduli space and compute it explicitly, thereby answering a question of Goulden, Harer, and Jackson.
title Refined lattice point counting on the moduli space of Klein surfaces
topic Algebraic Geometry
Mathematical Physics
Combinatorics
Geometric Topology
url https://arxiv.org/abs/2605.09526