Hierarchical Constraint Logic Programming Languages

约束逻辑编程（CLP）是扩展逻辑编程语言以包含约束的通用方案。然而，CLP语言，以及大多数其他基于约束的语言和系统，只允许程序员指定必须保持的约束。在许多应用程序中，例如交互式图形、页面布局和决策支持，需要表达偏好和严格的要求。作者设计了一种CLP方案的推广，层次约束逻辑规划（HCLP），它允许程序员用任意数量的偏好强度来表达所需约束和偏好约束。HCLP的开发将继续在实践方面进行，目标是改进语言方案实例的实现，包括结合有效的约束求解器和添加比较潜在解决方案的新方法。将通过使用交互式图形、文档格式、决策支持和调度作为测试应用程序来测试它的实用性。在理论方面，计划扩展约束层次结构的形式，包括只读变量和部分有序层次。

Constraint Logic Programming (CLP) is a general scheme for extending logic programming languages to include constraints. However, CLP languages, as well as most other constraint-based languages and systems, only allow the programmer to specify constraints that must hold. In many applications, such as interactive graphics, page layout, and decision support, one needs to express preferences as well as strict requirements. The authors have designed a generalization of the CLP scheme, Hierarchical Constraint Logic Programming (HCLP), which allows a programmer to express both required and preferential constraints, with an arbitrary number of strengths of preference. Development of HCLP will continue on the practical side, a goal is to improve the implementation of an instance of the language scheme, including incorporating efficient constraint solvers and adding new ways of comparing potential solutions. Its utility will be tested by using interactive graphics, as well as document formatting, decision support, and scheduling, as test applications. On the theoretical side, it is planned to extend the constraint hierarchy formalism to include read-only variables and partially ordered hierarchies.