Development of Knowledge Representation Language Based on the Inheritance Hierarchy Prolog

在本研究中，我们构建了一个知识表示系统PAL89，它是PA186的扩展，即处理继承层次的扩展Prolog，继承层次是由类和实例之间的包含关系形成的树结构。PA186采用类绑定变量(CBV)，即具有类约束的变量。CBV通过抑制不必要的回溯和穷举搜索，极大地提高了推理效率。CBV的扩展功能。(1)变量可以具有通过集合操作(差、并和交)计算的任何约束，这使得系统能够提供声明性多重继承表示。(2)实现了继承层次编译器和继承层次子句索引，提高了系统的运行速度。打字的诈骗案模式。PAL89中使用的所有对象都可以有类型。因此，PAL89可以看作是一个类型化的序言。类型在部分求值、学习和程序自动生成中起着重要的作用。带约束的变量。用户可以引入带有约束的新变量类及其统一。因此，用户可以通过带约束的变量来定义新的对象，并可以表示它们之间的关系。这就引出了“双重编程”的概念，即两步编程，第一步是定义对象，第二步是定义关系。

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.