The maintenance of semantic integrity has been recognized as a cornerstone issue for the development of databases and knowledge bases alike. Despite the extensive research conducted during the last two decades, semantic integrity maintenance has yet to become a practical technology. Furthermore, the need for modeling evolving domains has given rise to challenging research issues relating to the incorporation of time in knowledge bases. In this thesis, we study the problem of maintaining the integrity of temporal deductive knowledge bases. We argue that existing approaches in either temporal or deductive databases do not address the problem in a satisfactory manner, nor do they deal with all the issues involved in a unified framework. At first, we propose an assertion language that permits us to express different types of temporal assertions that are not expressible in other formalisms. We define the notion of temporal constraint satisfaction in a bitemporal context. We then follow two ...

There have been a large number of systems that integrate logic and objects (frames or classes) for knowledge representation and reasoning. Most of those systems give preeminence to logic and their objects lack the structure of frames. These choices imply a number of disadvantages, as the inability to represent exceptions and perform default reasoning, and the reduction in the naturalness of representation. In this paper, aspects of knowledge representation and reasoning in SILO, a system integrating logic in objects, are presented. SILO gives pre-eminence to objects. A SILO object comprises elements from both frames and classes. A kind of many-sorted logic is used to express object internal knowledge. Message passing, alongside inheritance, plays a significant role in the reasoning process. Control knowledge, concerning both deduction and inheritance, is separately and explicitly represented via definitions of certain functions, called meta-functions.

: In this paper the architecture of the VITAL-KR is described. Author: Enrico Motta and Arthur Stutt Collaborators (VITAL Partners): SYSECA - SYSECA TEMPS REEL (Coordinator) * NOTT - UNIVERSITY OF NOTTINGHAM * BULL - BULL CEDIAG AC - ANDERSEN CONSULTING ONERA - ONERA PTT - ROYAL PTT NEDERLAND NV * OU - THE OPEN UNIVERSITY * NOKIA - NOKIA RESEARCH CENTER * marked partners are involved in this task page 1 _____________________________________________________________________ The Open University 1991 1. INTRODUCTION As discussed in (Motta, 1991) both the current practice of industrial KBS, and the consensus among researchers (Frisch & Cohn, 1991) suggest that hybrid architectures, embedding a number of specialized representations/reasoners, are required to enable knowledge engineers to build efficient and powerful KBs. This is due to the fact that it has been recognized that no universal knowledge representation language exists, which can efficiently model all types of proble...