Using KIV to specify and verify architectures of knowledge-based systems

Abstract

examples. E.g. we have verified with KIV theorems of [3] used to distinguish different complexity classes in abduction. 7 Notice that these proofs are in no way trivial: the informal proof for theorem 5.3 of [3] took one page. It states that for the class of ordered monotonic abduction problems using a specific preference criterion, there is a polynomial algorithm for finding a best explanation. This is proved by presenting an algorithm that in polynomial time returns such a best explanation. Formalizing the informal arguments of the correctness proof for this algorithm results in several hundred (machine checkable) proof steps.Roughly, the interactive theorem proving system of KIV is comparable with systems as PVS [5] and Isabelle [22]. For our purpose, the KIV system is especially well suited due to its facilities for structuring specifications and software modules (including automatic generation of proof obligations), its proof engineering facilities (like an elaborated graphical user interface and reuse mechanisms), and the underlying dynamic logic.[20] identifies two kinds of approaches in software reuse: Supporting the software development process with reusable components or making parts of the development process reusable via program transformation techniques. Our approach provide support by formally specified and verified building blocks i.e. components. The latter approach is taken by KIDS/SPECWARE [28], [29] which provides support in the derivation of efficient implementations from formal specifications. Here, problem-solving methods are not "first-order citizens" that describe reusable components or architectures but secondorder transformation rules working on specifications. As in our approach, system development is viewed as a semiautomatic activity. At the technical level, the main differences are the use of dynamic logic for the declarative specification of procedural constructs in KIV and the use of category theory and sheaf theory to express transformations of algebraic specifications in SPECWARE.AMPHION ([18], [19]) is a knowledge-based software engineering system for the formal specification and automatic deductive synthesis of programs which consist of calls of subroutines from a library. It is specialized to application domains by means of a declarative domain theory and a library of subroutines. This specialization allows the automatic synthesis of programs from specifications. Our approach is more general-purpose (but, of course, less automatic): the programs developed are combinations and instantiations of (mostly domain-7. Theorem 4.4 and (the more difficult) theorem 5.3. For both theorems only the total correctness of the algorithms and, of course, not their complexity bounds have been proven. independent) problem-solving methods rather then simply a sequence of calls of subroutines from a library. Furthermore the (normal) user of the AMPHION system is not intended to create or modify the domain theory or the subroutine library. In our approach, the verification of user-defined problem-...

Knowledge engineering: Principles and methods

“…Meanwhile several papers have appeared providing declarative characterizations of PSMs (e.g. [17], [59], [139], [42]) and we assume that this will become an important line of future works on PSMs.…”

“…This shows strong similarities to recent work on problem-solving methods that define the competence of problem-solving methods in terms of assumptions over domain knowledge (which can be viewed as one or several components of a KBSs) and the functionality of elementary inference steps (cf. [59]). …”

“…As a consequence, verification of the functionality of a system with respect to its formal specification is not possible. Only recently, the need was recognized for formal specifications and conceptual models that guide and structure the validation and verification process ( [103], [78], [59]). …”

A software architecture for knowledge-based systems

“…We use the KIV system (Karlsruhe Interactive Veri®er) (see Reif, 1995) for this purpose. Fensel and SchoÈ negge (1997) and Fensel et al (1998c describe the veri®cation of our architectural speci®cations using KIV. It is an advanced tool for the construction of provably correct software.…”

Knowledge modeling directed by situation-specific models

“…KARL is one language for formalizing the procedural parts of a conceptual model as dynamic logic programs (involving loops, KNOWLEDGE MODELING WITH SSM-DKM conditional statements, etc. ), which a system called KIV can use to check that those procedural parts achieve their required function (Fensel & Schoenegge, 1997).…”