73.15 Operations for crossed modules

Special operations defined for crossed modules are stored in the record structure XModOps. Every crossed module X has X.operations := XModOps;.

    gap> RecFields( XModOps );
    [ "name", "operations", "Elements", "IsFinite", "Size", "=", "<", 
      "in", "IsSubset", "Intersection", "Union", "IsParent", "Parent", 
      "Difference", "Representative", "Random", "Print", "Kernel", 
      "IsAspherical", "IsSimplyConnected", "IsConjugation", 
      "IsTrivialAction", "IsCentralExtension", "DirectProduct", 
      "IsAutomorphismXMod", "IsZeroBoundary", "IsRModule",
      "InclusionMorphism", "WhiteheadPermGroup", "Whitehead", "Norrie",
      "Lue", "Actor", "InnerMorphism", "Centre", "InnerActor",
       "AutomorphismPermGroup", "IdentityMorphism", "InnerAutomorphism", ] 

Crossed modules X,Y are considered equal if they have the same source, boundary, range, and action. The remaining functions are discussed below and following section About actors.

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