GENERAL DESCRIPTION
The use of logic in computer science is very welldocumented. The exponential increase of literature on every area of computer science has forced both definition and use of logical formalisms for knowledge representation and reasoning into greater complexity, and this complexity has in turn necessitated a deeper study of the principles by which logical models may be constucted. It has become more and more apparent, say since the 1989' First International Conference on the Principles of Knowledge Representation and Reasoning (KR89), that knowledge representation models and reasoning models are only different views of the same common problem.
Different logicbased approaches to data and knowledge representation and reasoning are beginning to converge. It seems therefore useful to try to accelerate this process by trying to provide a survey, as uniform as possible presentation of the whole problem of logicbased modeling of data and knowlege, treating the subject on general theoretical lines, yet filled in with practical examples from realworld scenarios, problems and applications, with a particular attention paid to the borderlines and interrelationships among all logics presented.
There is as yet no unified theory of logicbased models for data and knowledge representation, and a good deal of practical systems and working devices are not logicbased in their design foundation and unsullied by any logical model. There is nevertheless a real need for the subject to be looked at as a whole.
