76.3 CoxeterLength

CoxeterLength( W , w )

returns the length of the permutation w, which corresponds to an element in the Coxeter group W, as a reduced expression in the standard generators.

    gap> W := CoxeterGroup( "F", 4 );;
    gap> p := PermCoxeterWord( W, [ 1, 2, 3, 4, 2 ] );
    ( 1,44,38,25,20,14)( 2, 5,40,47,48,35)( 3, 7,13,21,19,15)
    ( 4, 6,12,28,30,36)( 8,34,41,32,10,17)( 9,18)(11,26,29,16,23,24)
    (27,31,37,45,43,39)(33,42)
    gap> CoxeterLength( W, p );
    5
    gap> CoxeterWord( W, p );
    [ 1, 2, 3, 2, 4 ] 

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