FusionCharTableTom( tbl, tom )
FusionCharTableTom determines the fusion of the classes of elements
from the character table tbl into classes of cyclic subgroups on the
table of marks tom.
gap> a5c := CharTable( "A5" );;
gap> fus := FusionCharTableTom( a5c, a5 );
[ 1, 2, 3, 5, 5 ]
GAP 3.4.4