Assumptions of problem-solving methods refer to necessary applicability conditions of problem-solving methods, indicating that a problem-solving method is only applicable to realize a task, if the assumptions are met. In principle, such assumptions may refer to any kind of condition involved in a problem-solving method's applicability, including its required domain knowledge. In this paper, we propose a conceptual organization for assumptions of problem-solving methods and suggest a formal language to describe them. For illustration we take examples from the Propose & Revise problem-solving method and from diagnosis.

This paper deals with the formal specification of goals and their development. It addresses two issues: first, how goals can be formally specified and next, how genericity and reuse of knowledge can be supported by formal methods in Knowledge Engineering. At the knowledge level, goals and methods are distinct components. Various formal languages have been proposed to formalize methods (DESIRE, KARL, KBS SF, ML 2 , TFL etc). But goals have not precisely been defined nor really formally specified. This paper precisely focuses on the formal specification of goals by Abstract Data Types. Furthermore, the incremental development of a goal specification in reusing modular specifications by successive refinement and instantiation is emphasized. This approach for developing specifications from generic knowledge modules can be fruitfully extended to other categories of knowledge. The specification is based on PLUSS, an algebraic specification language offering several mechanisms for reuse: ge...

This paper presents the TASK framework which is intended to cover the life cycle of a Knowledge-Based System. TASK provides (i) a conceptual language which enable an informal specification at the knowledge level, (ii) a formal language TFL which permits an unambiguous specification and (iii) an operational shell TASK + which allows an efficient execution even for bad structured problems. This paper presents the different languages, the links between them and emphasizes the implementation stage. We show how TASK proposes a nice compromise solution between efficiency and expressivity. Introduction Now, the modeling approach [15] where the KnowledgeBased System (KBS) life-cycle is decomposed into several stages, is generally adopted in Knowledge Acquisition. Three main stages are considered: ffl the conceptualization stage allows to produce the model of expertise (ME). This model is an abstract description of an agent's problem-solving behavior (human or artifact). Different methodolog...

Meta-reasoning for flexible problem-solving and reuse of methods in Knowledge Engineering both needs a clear separation between the statement of problems or expected goal, and the description of methods to solve problems. Various formal languages have been proposed to formalize the methods (DESIRE, ML 2 , K BS SF, TFL etc), however the formal specification of goals has not been considered until now. This paper precisely focuses on the specification of goals by Abstract Data Types. The incremental development of a goal specification in reusing modular specifications by successive refinement and specialization is stressed. The specification is based on PLUSS, a language offering several mechanisms for reuse: genericity, enrichment of completed modules or of draft modules. The assignment problem type, and examples from Sisyphus I and Sisyphus II are used for illustration.

. This paper proposes a framework for the formal specification of a knowledge-based system and its intra-model verification. At a conceptual level, a knowledge-based system is specified in terms of problems, methods, knowledge. In previous papers we had propose a formal language to specify problem goals and process (methods) in using abstract data types. At present, the aim is to investigate how it is possible to prove that a process is relevant and correct with respect to a given problem. In this paper, we propose a formalization of the correctness and relevance notions for knowledge-based system specified at a conceptual level. Then, we present how the correctness proof of a process w.r.t a problem specification can be brought back to its relevance proof w.r.t this problem. 1. INTRODUCTION A large number of present engineering frameworks, referred as task-method frameworks, (e.g. TASK [10], Method-to-Task approch [16], Generic Tasks [6] [16], Components of Expertise [17] reflects N...