Development of Knowledge Representation Language Based on the Inheritance Hierarchy Prolog

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In this research we have constructed a knowledge representation system PAL89 which is an extention of pa186, that is, an extended prolog to deal with inheritance hierarchy which is a tree structure formed by the inclusion relation among classes and instances. Pa186 adopts class bound variables (CBVs), which are variables with class constraints. CBVs improve the inferential efficiency greatly by suppressing unnecessary backtracking and exhaustive searches.The characteristics of PAL89 include1. Extended functions of CBVs. (1) Variables can have any constraints which are computed by set operations (difference, union and intersection), which enables the system to provide declarative multiple inheritance representation. (2) A inheritance hierarchy compiler and inheritance hierarchy clause indexing are implemented, which makes the system faster.2. Typed cons patterns. AII objects used in PAL89 can have types. So PAL89 can be regarded as a typed prolog. Types play an important role in partial evaluation, learning and automatic program generation.3. Variables with constraints. Users can introduce new classes of variables with constraints and their unification. Therefore the user can define new objects by variables with constraints and can represent relations between them. This leads us to the concept of "DUAL PROGRAMMING", that is, two step Programming whose first step is defining objects and second step is defining relations.