Reiji Nakajima

Hierarchical program specification and verification -- a many-sorted logical approach

SummaryThe notion of abstractions in programming is characterized by the distinction between specification and implementation. As far as the specification structures are concerned, hierarchical program development with abstraction mechanisms is naturally regarded as a process of theory extensions in a many-sorted logic. To support such program development, a language called t is proposed with which one can structuredly build up theories and write their program implementation. There, the implementation is regarded as another level of theory extension, and the relation between the specification and the implementation of an abstraction is characterized in terms of a homomorphism between the two theories. On this formalism, a mechanizable proof method is introduced for validation of implementations of both data and procedural abstraction. Finally, a new data type concept is introduced to generalize the so-called type-parametrization mechanism. A justification of this concept within the first order logic is provided as well as its applications to program structuring and verification.

Modularization and Abstraction in Logic Programming

In knowledge information processing, the structuring of knowledge and algorithms is one of the key issues. The goal of this work is to introduce the concepts and mechanisms of abstraction, modularization and parameterization into logic programming, which is one of the preliminary steps toward creating a kernel language for fifth generation computer systems.

PROBLEM SOLVING AND INFERENCE MECHANISMS.

The heart of the fifth generation computer in prospect is powerful mechanisms for problem solving and inference. A deduction-oriented language is planned to be designed, which, with its processor, will form the core of the whole computing system. The language is based on predicate logic with the extended features of structuring facilities, meta structures and relational data base interfaces. Parallel computation mechanisms and specialized hardware architectures are extensively investigated to make possible efficient realization of the language features. The project includes an intelligent programming system, a knowledge representation language and system, and a meta inference system to be built on the core.