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math.CO2026
Twisted primitive group association schemes
Akihiro Higashitani, Masanari Kamiya, Hirotake Kurihara
We give results on the question of whether the intersection numbers of a primitive group association scheme determine it up to combinatorial isomorphism. For $G=\operatorname{PSL}(…
math.CO2026
Indecomposability of 0/1-polytopes
Akihiro Higashitani, Arnau Padrol, Raman Sanyal
We prove that every 0/1-polytope has a unique Minkowski decomposition into indecomposable polytopes, up to translation of summands. The summands lie in pairwise orthogonal subspace…
math.CO2026
Imprimitive association schemes and elimination theory
Akihiro Higashitani, Hirotake Kurihara
We prove that a commutative association scheme is imprimitive if and only if it admits a multivariate - or -polynomial structure with respect to an elimination-type monomial…