76.5 LeftDescentSet

LeftDescentSet( W, w )

The set of generators s such that l(sw), given as a list of integers.

    gap> W := CoxeterGroup( "A", 2 );;
    gap> w := PermCoxeterWord( W, [ 1, 2 ] );;
    gap> LeftDescentSet( W, w );
    [ 1 ]