53.17 FactorGroupNormalSubgroupClasses

FactorGroupNormalSubgroupClasses( G, classes )

returns the factor group of the group G modulo the normal subgroup of G that consists of the conjugacy classes whose positions are in the list classes.

    gap> ccl:= ConjugacyClasses( S4 );
    [ ConjugacyClass( S4, IdAgWord ), ConjugacyClass( S4, d ), 
      ConjugacyClass( S4, b ), ConjugacyClass( S4, a ), 
      ConjugacyClass( S4, a*d ) ]
    gap> S3:= FactorGroupNormalSubgroupClasses( S4, [ 1, 2 ] );
    Group( a, b )