Central series of cocommutative Hopf braces

Fuente: arXiv
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Main Authors: Bevilacqua, Maria, Gran, Marino, Sciandra, Andrea
Format: Preprint
Published: 2026
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_version_ 1866914531270197248
author Bevilacqua, Maria
Gran, Marino
Sciandra, Andrea
author_facet Bevilacqua, Maria
Gran, Marino
Sciandra, Andrea
contents By extending some classical results known for groups and skew braces, we define and investigate central series of cocommutative Hopf braces. Both left and right central series are defined using a $\star$-product that measures the difference between the two algebra operations, and naturally leads to introducing the notions of socle and of annihilator of a cocommutative Hopf brace. We characterize the central extensions relative to the subcategories of cocommutative Hopf algebras and of commutative and cocommutative Hopf algebras, respectively. Since the category of cocommutative Hopf braces is semi-abelian and it has enough projectives with respect to the class of cleft extensions, one can then establish suitable Hopf formulae for their homology. These are expressed in terms of the corresponding notions of relative commutators of cocommutative Hopf braces. In particular, the one relative to the subcategory of commutative and cocommutative Hopf algebras turns out to be the Huq commutator.
format Preprint
id arxiv_https___arxiv_org_abs_2605_03798
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Central series of cocommutative Hopf braces
Bevilacqua, Maria
Gran, Marino
Sciandra, Andrea
Rings and Algebras
Category Theory
Quantum Algebra
Representation Theory
Primary 16T05, 18E13, Secondary 18G50, 18A40, 16T25
By extending some classical results known for groups and skew braces, we define and investigate central series of cocommutative Hopf braces. Both left and right central series are defined using a $\star$-product that measures the difference between the two algebra operations, and naturally leads to introducing the notions of socle and of annihilator of a cocommutative Hopf brace. We characterize the central extensions relative to the subcategories of cocommutative Hopf algebras and of commutative and cocommutative Hopf algebras, respectively. Since the category of cocommutative Hopf braces is semi-abelian and it has enough projectives with respect to the class of cleft extensions, one can then establish suitable Hopf formulae for their homology. These are expressed in terms of the corresponding notions of relative commutators of cocommutative Hopf braces. In particular, the one relative to the subcategory of commutative and cocommutative Hopf algebras turns out to be the Huq commutator.
title Central series of cocommutative Hopf braces
topic Rings and Algebras
Category Theory
Quantum Algebra
Representation Theory
Primary 16T05, 18E13, Secondary 18G50, 18A40, 16T25
url https://arxiv.org/abs/2605.03798