1.6 SubgroupGPL

SubgroupGPL( pres, number )
SubgroupGPL( pres, sgrname )

SubgroupGPL( pres, number ) returns the subgroup labeled by entry number number in the list pres.subgroups. pres must be a presentation. Note that a presentation is not a group:

   gap> m12 := GroupPresentationGPL( "M12", 1);
   GroupPresentationGPL( "M12", 1 )
   gap> InitializeGroupPresentationGPL( m12 );
   gap> m11 := SubgroupGPL( m12, 1);
   M11
   gap>  Index(m12, m11);
   Error, <G> must be a group in
   Index( m12, m11 ) called from
   main loop
   brk> 
   gap> gm12 := m12.group;
   M12
   gap> Index(gm12, m11);
   12

SubgroupGPL( pres, sgrname ) returns the subgroup of name sgrname defined in the list pres.subgroups :

  gap> m12 := GroupPresentationGPL( "M12", 1);
  GroupPresentationGPL( "M12", 1 )
  gap> InitializeGroupPresentationGPL( m12 );
  gap> s6 := SubgroupGPL(m12, "S6");
  S6
  gap> gm12 := m12.group;
  gap> opsm12s6 :=  OperationCosetsFpGroup( gm12, s6 );;
  gap> Size(opsm12s6);
  95040