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Published online by Cambridge University Press: 03 April 2025
It is proven that a matched pair of actions on a Hopf algebra H is equivalent to the datum of a Yetter–Drinfeld brace, which is a novel structure generalizing Hopf braces. This [-30pt] improves a theorem by Angiono, Galindo, and Vendramin, originally stated for cocommutative Hopf braces. These Yetter–Drinfeld braces produce Hopf algebras in the category of Yetter–Drinfeld modules over H, through an operation that generalizes Majid’s transmutation. A characterization of Yetter–Drinfeld braces via 1-cocycles, in analogy to the one for Hopf braces, is given.
Every coquasitriangular Hopf algebra H will be seen to yield a Yetter–Drinfeld brace, where the additional structure on H is given by the transmutation. We compute explicit examples of Yetter–Drinfeld braces on the Sweedler’s Hopf algebra, on the algebras $E(n)$, on
$\mathrm {SL}_{q}(2)$, and an example in the class of Suzuki algebras.
The authors were partially supported by the Ministry for University and Research (MUR) within the National Research Project (PRIN 2022) “Structures for Quivers, Algebras and Representations” (SQUARE) Project 2022S97PMY. The first-named author was partially funded by the Vrije Universiteit Brussel Bench Fee for a Joint Doctoral Project, grant number OZR4257, and partially supported through the FWO Senior Research Project G004124N.