Overlarge sets of mixed4 triangle decomposition,denoted by OLT_4(v,1,4),is a collection {(Xx},A_x):(x∈X},)where X is a(v+1)-set,each(Xx},A_x) is a mixed4 triangle decomposition.

The large set problem in the combinatorial design theory has a long history and a variety of applications.

A large set of disjoint PMTS(v,λ)denoted by LPMTS(v,λ),is a collection of(v_2)/λdisjoint pure Mendelsohn triple systems on X,and∪_iB_i is a partition of all cyclic triples from X.

It is shown that largest maximal set α(a)is a filter,when L is a non-trivial complete distributive lattice or the largest element 1 in L isn′t a molecular.

Thus it certainly reduces the amount of scanning transactions when finding the k+1-large itemsets next time and optimizes the AprioriTid algorithm to some extent.

Association rule is an important database discovery method,whose kernel is the acquisition of large itemsets.

Discussion is made,in terms of economic globalization,on the necessity to implement the strategy of large group enterprises and the problems concerning the transnational management of businesses.

According to possible issues met in the coal mine resources integration in the coal mine groups and national policy requirements on building large groups and large bases, it is pointed out that coal mining groups should take measures in strategic development such as resources, investment, and going out, which has certain guiding significance for expansion of coal enterprises.