Workshop on Comparing Description and Frame Logics

The specification of reusable terminological knowledge is one of the key issues in today’s knowledge engineering. Providing formal languages with precise semantics and inference support can significantly support this activity. The aim of the workshop was to understand and to compare existing approaches developed in other research communities. We investigated research on description languages and research on object-oriented databases. Both provide the combination of rich terminological modelling primitives with well studied semantics and inference support. To better understand and compare them as well as to highlight common aspects and differences were the goals of the workshop. Knowledge-based systems (KBSs) consist of large amount of domain knowledge and problem-solving methods that describes the inference process of the system [SWA+94]. The domain knowledge defines concepts, properties, relationships, heuristic rules, instances etc. that are necessary to define the application problem and its solution process. Recent work on ontologies aim at developing reusable terminological knowledge which improves knowledge sharing and prevents a development from scratch for each new system ([ToA94], [FFR97], [Gua97], [HSW97]). Therefore, the specification of terminological knowledge is one of the key issues in today’s knowledge engineering. Given this fact, there is clear need to improve existing approaches to specification languages for KBSs. Some of them are rather weak in supporting terminological representation because they focus on other aspects (for example, (ML) 2 [vHB92] or DESIRE [vLPT93]); others use different techniques for representing terminologies and provide little understanding of the advantages and disadvantages of the different choices. Specification approaches that aim at rich terminological specification formalisms are either inspired by Description Logics or by approaches of object-oriented databases and logic programming. 2 The language KARL [FAS] uses a customization of Frame logic [KLW95] for this purpose. Frame logic (FL) accounts in a clean, declarative fashion for most of the structural aspects of object-oriented and framebased languages. The EXPECT approach [SwG95] for specifying and implementing knowledge based systems is based on LOOM [Mac90], a Description Logic (DL) with high expressive power. The representation language CARIN [LeR96a], [LeR96b] combines DL with a Datalog like rule language. Therefore it was quite natural to organize a workshop that aims at a better understanding of the different possibilities by comparing the existing approaches. We focused our attention on DLs and FL, which are the technical core of many of 1. March 26-27, 1997 at the Institut AIFB, University of Karlsruhe, Karlsruhe, Germany. For more information see http:// www.aifb.uni-karlsruhe.de/WBS/dfe/dlfl. 2. See [FvH94] and [Fen95] for surveys of specification languages in knowledge engineering.