This paper reports on an investigation into a formal language for specifying kads models of expertise. After arguing the need for and the use of such formal representations, we discuss each of the layers of a kads model of expertise in the subsequent sections, and define the formal constructions that we use to represent the kads entities at every layer: order-sorted logic at the domain layer, meta-logic at the inference layer, and dynamic-logic at the task layer. All these constructions together make up (ml) 2 , the language that we use to represent models of expertise. We illustrate the use of (ml) 2 in a small example model. We conclude by describing our experience to date with constructing such formal models in (ml) 2 , and by discussing some open problems that remain for future work. 1 Introduction One of the central concerns of "knowledge engineering" is the construction of a model of some problem solving behaviour. This model should eventually lead to the construction of a...

A novel approach to the verification of meta-interpreters is introduced. We apply a general purpose verification method for logic programs, proposed in [28], to the case study of the Vanilla and other logic meta-interpreters. We extend the standard notion of declarative correctness, and design a criterion for proving correctness of meta-interpreters in a general sense, including amalgamated and reflective meta-interpreters. The contribution of this paper can be summarized as follows: under certain natural assumptions, all interesting verification properties lift up from the object program to the meta-program, including partial correctness, termination, absence of errors, call patterns persistence, correct instances of queries, computed instances of queries. Interestingly, it is possible to establish these results on the basis of purely declarative reasoning, using the mentioned proof method. We believe that the obtained results illustrate the broad applicability of the adopted verifi...

. This paper reports on a number of implementations for a suite of composition operations of logic programs. We present and compare three implementations, which rely on different techniques: metaprogramming, program transformations, and extensions to the WAM, respectively. In particular, we show how the third approach reduces the drawbacks of the other two approaches, while retaining their advantages. 1 Introduction The use of logic programming in different application domains has called for various extensions of the basic paradigm grounded on Horn clauses, in order to increase the expressive power of the formalism and to broaden its applicability. Indeed, the main aim of projects such as the Esprit Basic Research Action Compulog [9] is to identify the extension(s) of the basic paradigm of logic programming, which could form a computational logic for addressing the various aspects of computing. Some of these extensions are aimed at providing enhanced knowledge representation an...

In this paper we discuss an extension of Partial Deduction in the framework of structured logic programs. The class of programs we consider includes statically configured systems such as block- and inheritance-based systems, as well as more dynamic configurations which support hypothetical reasoning and viewpoints. We show that the basic Partial Deduction definition can be extended to deal with a richer class of programs while maintaining, under appropriate closedness conditions, the properties of soundness and completeness of the transformation which hold in the case of logic programming. 1