PermCosetsSubgroup( W, H )
returns the list of permutations induced by the standard generators of
the Coxeter group W on the cosets of the Coxeter subgroup H. The
cosets are in the order determined by the result of the function
ReducedRightCosetRepresentatives( W, H ).
gap> W := CoxeterGroup( "F", 4 );;
gap> PermCosetsSubgroup( W, ReflectionSubgroup( W, [ 1, 2, 3 ] ) );
[ ( 4, 5)( 6, 7)( 8,10)(16,18)(17,20)(19,21),
( 3, 4)( 7, 9)(10,12)(14,16)(15,17)(21,22),
( 2, 3)( 4, 6)( 5, 7)( 9,11)(12,14)(13,15)(17,19)(20,21)(22,23),
( 1, 2)( 6, 8)( 7,10)( 9,12)(11,13)(14,15)(16,17)(18,20)(23,24) ]
This function requires the package "chevie" (see RequirePackage).
GAP 3.4.4