Constructing geometric realizations of birational maps between Mori Dream Spaces

Fuente: arXiv
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Auteurs principaux: Barban, Lorenzo, Occhetta, Gianluca, Conde, Luis E. Sol á
Format: Preprint
Publié: 2025
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author Barban, Lorenzo
Occhetta, Gianluca
Conde, Luis E. Sol á
author_facet Barban, Lorenzo
Occhetta, Gianluca
Conde, Luis E. Sol á
contents We construct geometric realizations -- projective algebraic versions of cobordisms -- for birational maps between Mori Dream Spaces. We show that these geometric realizations are Mori Dream Spaces, as well, and that they can be constructed so that they induce factorizations of the original birational maps as compositions of wall-crossings. In the case of toric birational maps between normal $\mathbb{Q}$-factorial, projective toric varieties, we provide several SageMath functions to work with $\mathbb{C}^*$-actions and birational geometry; in particular we show how to explicitly construct a moment polytope of a toric geometric realization. Moreover, by embedding Mori Dream Spaces in toric varieties, we obtain geometric realizations of birational maps of Mori Dream Spaces as restrictions of toric geometric realizations. We also provide examples and discuss when a geometric realization is Fano.
format Preprint
id arxiv_https___arxiv_org_abs_2503_23790
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Constructing geometric realizations of birational maps between Mori Dream Spaces
Barban, Lorenzo
Occhetta, Gianluca
Conde, Luis E. Sol á
Algebraic Geometry
Primary 14E30, Secondary 14L30, 14L24, 14M25
We construct geometric realizations -- projective algebraic versions of cobordisms -- for birational maps between Mori Dream Spaces. We show that these geometric realizations are Mori Dream Spaces, as well, and that they can be constructed so that they induce factorizations of the original birational maps as compositions of wall-crossings. In the case of toric birational maps between normal $\mathbb{Q}$-factorial, projective toric varieties, we provide several SageMath functions to work with $\mathbb{C}^*$-actions and birational geometry; in particular we show how to explicitly construct a moment polytope of a toric geometric realization. Moreover, by embedding Mori Dream Spaces in toric varieties, we obtain geometric realizations of birational maps of Mori Dream Spaces as restrictions of toric geometric realizations. We also provide examples and discuss when a geometric realization is Fano.
title Constructing geometric realizations of birational maps between Mori Dream Spaces
topic Algebraic Geometry
Primary 14E30, Secondary 14L30, 14L24, 14M25
url https://arxiv.org/abs/2503.23790