CharTableFactorGroup( tbl, classes_of_normal_subgroup )
returns the table of the factor group of tbl with respect to a
particular normal subgroup: If the list of irreducibles stored in
tbl.irreducibles
is complete, this normal subgroup is the normal
closure of classes_of_normal_subgroup;
otherwise it is the intersection of kernels of those irreducibles stored
on tbl which contain classes_of_normal_subgroups in their kernel
--that may cause strange results.
gap> s4:= CharTable( "Symmetric", 4 );; gap> PrintCharTable( CharTableFactorGroup( s4, [ 3 ] ) ); rec( size := 6, identifier := "S4/[ 3 ]", order := 6, name := "S4/[ 3 ]", centralizers := [ 6, 2, 3 ], powermap := [ , [ 1, 1, 3 ], [ 1, 2, 1 ] ], fusions := [ ], fusionsource := [ "S4" ], irreducibles := [ [ 1, -1, 1 ], [ 2, 0, -1 ], [ 1, 1, 1 ] ], orders := [ 1, 2, 3 ], classes := [ 1, 3, 2 ], operations := CharTableOps ) gap> s4.fusions; [ rec( map := [ 1, 2, 1, 3, 2 ], type := "factor", name := "S4/[ 3 ]" ) ]
GAP 3.4.4