We comment on the subsethood measure and weak subsethood measure defined by
Young and give some new definitions of subsethood measure. We present some
subsethood measure formulas from the point of view of set-theoretic approa
ch, and from fuzzy implication operator. Finally an application of subsetho
od measure to cluster validity is shown. (C) 1999 Elsevier Science B.V. All
rights reserved.