An Integration of Prolog and Neural Networks to Deal with Sensibility

Abstract

This paper depicts the integrated system Neuro-Prolog/II which is a synergistic cooperation of both Prolog interpreter C-Prolog and neural network simulator SunNet, each focusing on different aspects of the problem. By using Neuro-Prolog/II, users can deal with both logical information (i. e. laws, well-defined knowledge and logical rules) and non-logical information (i. e. human sensibility, ill-defined knowledge and taste) concurrently in a single system. In Neuro-Prolog/II, logical information is handled in Prolog and non-logical information is handled in neural network. This paper discusses how they may be integrated to provide a more unified and comprehensive treatment of these kinds of information. Prolog and neural network communicate with each other by execution of P-rule and N-rule. P-rule is a conventional rule used in Prolog, whereas N-rule is newly proposed for Neuro-Prolog/II to activate its corresponding neural network. The syntactic structure of N-rule is "head : ～body" which is very similar to the syntax of P-rule. We also describe a general protocol for interaction between P-rule and N-rule. If a goal can be unified with the head of N-rule, the neural network whose input layer and output layer are respectively assigned to the body and head of N-rule is activated. Since, both P-rule and N-rule can activate each other in Neuro-Prolog/II, this protocol enables Neuro-Prolog/II to deal with problems containing both logical and non-logical information in an unified manner. Furthermore, we have also developed a trial application system in Neuro-Prolog/II to demonstrate the advantages of Neuro-Prolog/II in real world problems. The trial system selects appropriate color arrangement of an outline picture among candidate colors. In the trial system, images of colors are handled in N-rules and heuristic rules of color arrangement are described in P-rules. As a result, a lot of features of human sensibility (i. e. individuality) can be handled in logic programs by using Neuro-Prolog/II. Neuro-Prolog/II is now running on SPARC station 330.