On $n$-isoclinism of skew braces
Risa Arai, Cindy Tsang
TL;DR
This work extends the group-theoretic notion of n-isoclinism to skew braces by developing a verbal/marginal framework tailored to the dual-operation structure of braces. It introduces verbal left/right series and verbal sub-skew braces, along with marginal left ideals, to provide robust invariants for isoclinism that avoid issues with naive star-product-based definitions. A new W-isoclinism is proposed, using Core$_A$(M_W(A)) to form quotients and commuting diagrams for skew-brace words, with the strength of the notion decreasing as n grows. The paper also provides concrete brace examples showing genuine differences between quotient constructions and connects the new framework to classical isoclinism in suitable special cases.
Abstract
The purpose of this paper is to explore possible definitions of $n$-isoclinism for skew braces. We also introduce the notions of verbal sub-skew braces and marginal left ideals.
