Several important classes of normal logic programs, including the classes of acyclic, acceptable, and locally hierarchical programs, have the property that every program in the class has a unique two-valued supported model. In this paper, we call such classes unique supported model classes. We analyse and characterize these classes by means of operators on three-valued logics. Our studies will motivate the definition of a larger unique supported model class which we call the class of Phi-accessible programs. Finally, we show that the class of Phi -accessible programs is computationally adequate in that every partial recursive function can be implemented by such a program.
Seda, A. K.,
& Hitzler, P.
(1999). Characterizations of Classes of Programs by Three-Valued Operators. Proceedings of the 5th International Conference on Logic Programming and Nonmonotonic Reasoning, 357-371.