The Research Of Construction Algorithm Of Fuzzy Concept Lattice Based On Constraints

Concept lattices are the core data structures in the theory of formal concept analysis. It has been widely used in many fields such as knowledge discovery and information retrieval. The concept lattice based on precise formal context can represent precisely and definite information. In real applications, however, the messages are often vague and uncertain. So the fuzzy concept lattice is proposed by the scholars, combining fuzzy logic and the formal concept analysis theory. Constructing fuzzy concepts directly is still one of most important issues. However, the general process of constructing fuzzy concept lattice does not take user’s requirement into account. Users sometimes are not interested in all intensions of attributes set in fuzzy concept lattice node. In order to enhance the practicability of the fuzzy concept lattice which can meet the need of users, this paper conducted the following research:First, the attribute in which the user is interested and the degree of membership which is greater than the threshold value are defined as a constraint condition. We divide the constraints into five categories: Single-constraint, And-constraint, Or-constraint, And-or-constraint and Or-and-constraint bye the relations among attributes. And then, a construction algorithm based on constraints(Upper Interval Concept Lattice, UICL) is presented. This algorithm presents a bottom-up method to compute the fuzzy concept lattice by making use of the monotone relation between father fuzzy concept’s intent and child fuzzy concept’s intent. And the efficiency of building the fuzzy concept lattice is improved by pruning technology.Then, based on the UICL algorithm, the attribute in which the user is interested and the degree of membership in any interval are defined as a constraint condition. And a construction algorithm based on interval constraint(Interval Fuzzy Concept Lattice, IFCL) is presented. This algorithm adopts the combination of bottom-up and top-down method to structure the fuzzy concept lattice which meets the interval constraint.Finally, the experiment results that UICL algorithm and IFCL algorithm can structure the fuzzy concept lattice which meets the constraints and can reduce the storage space of fuzzy concept lattice.