The Poincaré polynomial of the type B analogue of $\overline{\mathcal{M}}_{0,n+1}$

Fuente: arXiv
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Main Authors: Ferroni, Luis, Pagaria, Roberto, Vecchi, Lorenzo
Format: Preprint
Published: 2026
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author Ferroni, Luis
Pagaria, Roberto
Vecchi, Lorenzo
author_facet Ferroni, Luis
Pagaria, Roberto
Vecchi, Lorenzo
contents We establish formulas for the Poincaré polynomial of the type B analogue of the Deligne--Knudsen--Mumford moduli space of rational curves with $n$ marked points, providing type B counterparts to results by Keel, Manin, Getzler and Yuzvinsky. We establish functional and differential equations satisfied by the bivariate exponential generating function of these polynomials. We show how this generating function relates to the classical one in type A. We deduce the gamma-positivity of these polynomials via a quadratic recursion and discuss a type B analogue of a formula found by Aluffi, Marcolli and Nascimento in type A.
format Preprint
id arxiv_https___arxiv_org_abs_2603_01956
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle The Poincaré polynomial of the type B analogue of $\overline{\mathcal{M}}_{0,n+1}$
Ferroni, Luis
Pagaria, Roberto
Vecchi, Lorenzo
Combinatorics
Algebraic Geometry
We establish formulas for the Poincaré polynomial of the type B analogue of the Deligne--Knudsen--Mumford moduli space of rational curves with $n$ marked points, providing type B counterparts to results by Keel, Manin, Getzler and Yuzvinsky. We establish functional and differential equations satisfied by the bivariate exponential generating function of these polynomials. We show how this generating function relates to the classical one in type A. We deduce the gamma-positivity of these polynomials via a quadratic recursion and discuss a type B analogue of a formula found by Aluffi, Marcolli and Nascimento in type A.
title The Poincaré polynomial of the type B analogue of $\overline{\mathcal{M}}_{0,n+1}$
topic Combinatorics
Algebraic Geometry
url https://arxiv.org/abs/2603.01956