=+Let T(m)(w) = (T(")(w) ,..., T.") (@) be that permutation

(f) ,. . ., (1) of

(1 ,. .., n) for which X, (w) < X,(w) < ... < X, (w). Let Y, be the rank of X among X1 ,..., X ,,: Y =r if and only if X; < X ,, for exactly r - 1 values of i preceding n.