“…(2) A superficial element of a for M is an element be a for which there exist integers c > 0, d > 0 such that (a n+c M:b) n a d M = a n M for all sufficiently large n. Thus, we call a 1 ,..., a T an a-superficial M-sequence if a i is a superficial element of q for M/q^-^ M, i = l,...,r, cf. (6). Superficial elements (hence, by reduction,superficial sequences) have been proved as a useful concept in studying Hilbert-Samuel functions and multiplicities, see, for example, ( 18, ch.…”