The frequent subset problem is defined as follows. Suppose UU={1, 2,ldots…,N} is the universe, and S_{1}S1, S_{2}S2,ldots…,S_{M}SMare MM sets over UU. Given a positive constant alphaα, 0<alpha leq 10<α≤1, a subset BB (B eq 0B≠0) is α-frequent if it is contained in at least alpha MαM sets of S_{1}S1, S_{2}S2,ldots…,S_{M}SM, i.e. left | left { i:Bsubseteq S_{i} ight } ight | geq alpha M∣{i:B⊆Si}∣≥αM. The frequent subset problem is to find all the subsets that are α-frequent. For example, let U={1, 2,3,4,5}U={1,2,3