Non-abelian tensor and exterior products modulo \(q\) and universal \(q\)- central relative extension
Let \(G\) be a discrete group and \(q\) a positive integer. For two crossed \(G\)-modules, \textit{R. Brown} and \textit{J.-L. Loday} [Topology 26, 311-335 (1987; Zbl 0622.55009)] introduced notions of a non-abelian tensor product and of an exterior product. In the paper under review, analogues modulo \(q\) are proposed and their properties are studied. Thereafter notions of a \(q\)-central relative extension and that of a universal \(q\)- central relative extension are introduced, a condition is given for the existence of a universal \(q\)-central relative extension, and a description of the latter is offered involving the exterior product modulo \(q\).
universal \(q\)-central relative extension
scientific article; zbMATH DE number 60680
scientific article