Reuse: Revisiting Sisyphus-VT

Reuse has long been a major goal of the Knowledge Engineering community. The focus of this paper is the reuse of domain knowledge acquired for an initial problem solver, with a further problem solver. For our analysis we chose a knowledge base system written in CLIPS based on the propose-andrevise (PnR) problem solver, and which had a lift/elevator knowledge base (KB). Given the nature of the problem solver, the KB contained 4 components, namely an ontology, procedural statements which specify how the artifact, the lift, could be enhanced/modified, a set of constraints to be satisfied, and a set of fixes to be applied when constraint violations occurred. These 4 components were first extracted manually, and were used with both an Excel spreadsheet and a constraint problem solver (ECLiPSe) to solve a range of tasks. The next phase was to implement ExtrAKTor which extracts the same 4 knowledge sources virtually automatically from the CLIPS knowledge base (held by Protégé), and transforms these so that they are usable with a number of problem solvers. To date Excel & ECLiPSe have been selected, and again we have demonstrated that the resulting systems are able to solve a variety of lift configuration tasks. This is in contrast to earlier work which produced abstract formulations of the problem but which were unable to perform reuse of actual knowledge bases.