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arXiv · 2609.08553

Fundamentals of the cocyclic development of Hadamard matrices over loops

Raúl M. Falcón·Manuel González-Regadera·Félix Gudiel
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Abstract

This paper establishes a formal framework for the cocyclic development of Hadamard matrices over loops based on a novel cohomology theory with associativity obstructions. In this context, we formalize the notion of a loop-cocyclic Hadamard matrix, so that both the classical cocyclic Hadamard matrices over groups and the recently introduced pseudococyclic Hadamard matrices over loops are naturally embedded within this broader algebraic architecture. To validate the computational viability of this framework, we prove the existence of four new Hadamard equivalence classes of order 24 and eight new classes of order 28 that are strictly non-cocyclic over any finite group, arising uniquely as loop-cocyclic developments over Moufang and right Bol loops.

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Raúl M. Falcón, Manuel González-Regadera, Félix Gudiel. 2026-09-08. Fundamentals of the cocyclic development of Hadamard matrices over loops. https://arxiv.org/abs/2609.08553

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