Prolog for logic programming is one of the most intensively studied software languages in the 1980s. During the same period, the data-flow model for parallel computation attracted a lot of attention of researchers in the computer science; hence, it was very natural that several approaches were tried toward combining the two and implementing logic programs in parallel machines with the data-flow architecture. These approaches, however, were rather indirect ones in the sense that they developed programs describing AND/OR-parallelism for deduction using a data-flow language and executed them in a data-flow computer, and yet did not devise a ‘direct’ model for parallel execution (reasoning) of a logic program. This book discusses fuzzy logic inferencing for Pong; dislog; SEProlog; and provides direct graphical representations of first-order logic for inference.