NON-MONOTONIC KNOWLEDGE EVOLUTION IN VLKDBs Abstract

Non-monotonic knowledge evolutions and exceptions constitute a complex theoritical and practical prob-lem. The state of the art shows a rich and surprising diversity of approaches. Their study along a common framework reveals a few basic issues which require fur-ther theoritical investigation. In the context of very large knowledge/data bases (VLKDBs), specific constraints must be taken into ac-count. They require a specific approach of the prob-lem, which can be sketched by a set of basic guidelines. In order to illustrate the importance of the prob-lem, a proposal called semantic tolerance is briefly described. Its various relationships with user inter-faces, rule administration, advanced design techniques and long-term transactions show that non-monotonic knowledge evolution constitute a central problem in advanced databases, and consequently would deserve a major research effort by the database community.