44.7 Abelian Invariants for Subgroups

Using variations of coset enumeration it is possible to compute the abelian invariants of a subgroup of a finitely presented group without computing a complete presentation for the subgroup in the first place.

  • AbelianInvariantsSubgroupFpGroup( G, H ) F

    is a synonym for AbelianInvariantsSubgroupFpGroupRrs(G,H).

  • AbelianInvariantsSubgroupFpGroupMtc( G, H ) F

    uses the Modified Todd-Coxeter method to compute the abelian invariants of a subgroup H of a finitely presented group G.

  • AbelianInvariantsSubgroupFpGroupRrs( G, H ) F
  • AbelianInvariantsSubgroupFpGroupRrs( G, table ) F

    uses the Reduced Reidemeister-Schreier method to compute the abelian invariants of a subgroup H of a finitely presented group G.

    Alternatively to the subgroup H, its coset table table in G may be given as second argument.

  • AbelianInvariantsNormalClosureFpGroup( G, H ) F

    is a synonym for AbelianInvariantsNormalClosureFpGroupRrs(G,H).

  • AbelianInvariantsNormalClosureFpGroupRrs( G, H ) F

    uses the Reduced Reidemeister-Schreier method to compute the abelian invariants of the normal closure of a subgroup H of a finitely presented group G.

    See Subgroup Presentations for details on the different strategies.

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    GAP 4 manual
    February 2000