ALEXANDROS CHORTARAS
School of Electrical and Computer Engineering, National Technical University of Athens, 157 80 Zografou, Athens, Greece
GIORGOS STAMOU
School of Electrical and Computer Engineering, National Technical University of Athens, 157 80 Zografou, Athens, Greece
ANDREAS STAFYLOPATIS
School of Electrical and Computer Engineering, National Technical University of Athens, 157 80 Zografou, Athens, Greece

Received 26 October 2006
Revised 1 October 2008

Fuzzy logic programming has been lately used as a general framework for representing and handling imprecise knowledge. In this paper, we define the syntax and the semantics of definite weighted fuzzy logic programs, which extend definite fuzzy logic programs by allowing the inclusion of different significance weights in the individual atoms that make up the antecedent of a fuzzy logic rule. The weights add expressiveness to a fuzzy logic program and allow the determination of the level up to which an atom in the antecedent of a rule may affect the truth value of its consequent. In describing the semantics of definite weighted fuzzy logic programs we introduce the notion of the generalized weighted fuzzy conjunction operator, which can be regarded as a weighted t-norm based aggregation. We determine the properties of generalized weighted fuzzy conjunction operators and provide several examples. A methodology for constructing generalized weighted fuzzy conjunction operators using generator functions of existing t-norms is also introduced. Finally, a method for setting up a parametric weighted fuzzy logic program and automatically adapting the weights of its rules using a numerical dataset is developed.

Fuzzy logic programming; fuzzy logic; logic programming; triangular norms; weighted conjunctions; knowledge adaptation; rule extraction