Existing explanation systems for deductive databases show forests of proof trees. Although proof trees are often useful, they are only one possible interesting representation. We argue that an explanation system for deductive databases must be able to generate explanations at several levels of abstraction. One possible and well known technique to achieve this exibility is to instrument meta-int...

This paper introduces a temporal deductive database system featuring a logic programming language and an algebraic front-end. The language, called Temporal Datalog, is an extension of Datalog based on a simple temporal logic with two temporal operators, namely first and next. Programs of Temporal Datalog are considered as temporal deductive databases, specifying temporal relationships among dat...

The goal of deductive design is the systematic construction of a system implementation starting from its behavioural specification according to formal, provably correct rules. We use Gofer/Haskell to formulate a functional model of directional, synchronous and deterministic systems with discrete time. The associated algebraic laws are then employed in deductive hardware design of basic combinat...

Formal deductive systems play an important role in computer science, particularly in the areas of logic and semantics of programming languages. They are employed in three different, but obviously related roles. Firstly, they are used to specify logics, type systems, operational semantics and other aspects of languages. Secondly, they form the basis for the implementation of such deductive syste...

This paper presents the declarative extension of the deductive database system LOLA to the object-oriented deductive database system O!-LOLA. The model used for O!-LOLA is \objects as theories", extended by state evolution. O!-LOLA combines logic programming and OO programming in two diierent w ays: First, methods are implemented as logic programs. These methods can be inherited, encapsulated a...