factor system


Using the notation in the entry Group CohomologyMathworldPlanetmathPlanetmathPlanetmath, a 2-cocycle or factor system is a map ϕ:G×GM such that for all α,β,γG, we have

αϕ(β,γ)-ϕ(αβ,γ)+ϕ(α,βγ)-ϕ(β,γ)=0.

Factor systems play a role in determing classes of group extensionsMathworldPlanetmath of G by M in the case where M is taken to be an abelianMathworldPlanetmath normal subgroupMathworldPlanetmath of G.

Title factor system
Canonical name FactorSystem
Date of creation 2013-03-22 14:23:28
Last modified on 2013-03-22 14:23:28
Owner mathcam (2727)
Last modified by mathcam (2727)
Numerical id 4
Author mathcam (2727)
Entry type Definition
Classification msc 20J06