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math.CO2026

Minkowski decomposability of symmetric edge polytopes

Akihiro Higashitani, Aki Mori

In this paper, we study the Minkowski decomposability of symmetric edge polytopes of a finite simple graph on vertex set . More precisely, we give a complete cha…

math.CO2026

A matroidal criterion for flow polytopes to be order polytopes

Akihiro Higashitani, Hidefumi Ohsugi

Flow polytopes of directed acyclic graphs form a central class of lattice polytopes in algebraic, geometric, and enumerative combinatorics. Order polytopes are one of the best unde…

math.CO2026

Characterization and chromatic number of triangle-free graphs with diameter 2

Akihiro Higashitani, Diogo Kendy Matsumoto, Naoki Matsumoto

In this paper, we consider triangle-free graphs with diameter 2. If a triangle-free graph with diameter 2 is not isomorphic to a star, then the radius of is also 2, where s…

math.CO2025

Order polytopes of graded posets are gamma-effective

Alessio D'Alì, Akihiro Higashitani

Order polytopes of posets have been a very rich topic at the crossroads between combinatorics and discrete geometry since their definition by Stanley in 1986. Among other notable r…

math.CO2025

New kinds of block diagonal matching fields and toric degenerations of Grassmannians

Akihiro Higashitani, Nobukazu Kowaki

Block diagonal matching field has many previous works. In general, a coherent matching field induces a monomial order to Plücker algebra, and block diagonal matching fields are a k…

math.CO2024

On the Ehrhart Theory of Generalized Symmetric Edge Polytopes

Robert Davis, Akihiro Higashitani, Hidefumi Ohsugi

The symmetric edge polytope (SEP) of a (finite, undirected) graph is a centrally symmetric lattice polytope whose vertices are defined by the edges of the graph. SEPs have been stu…