This paper describes a language that is intended to support software engineers in the development of information systems throughout the software lifecycle. This language is not a programming language. Following the example of a number of other software engineering projects, our work is based on the premise that information system development is knowledge-intensive and that the primary responsibility of any language intended to support this task is to be able to formally represent the relevant knowledge.

An important requirement of advanced temporal applications is the ability to deal with definite, indefinite, finite and infinite temporal information. There is currently no database model which offers this functionality in a single unified framework. We argue that the combination of relational databases and temporal constraints offers a powerful framework which addresses these needs. In this thesis we develop the foundations of a theory of temporal constraint databases and indefinite temporal constraint databases. At first, we study a hierarchy of parameterized database models: ML -relational databases, L-constraint databases and indefinite L-constraint databases. The language L, the parameter, defines the constraint vocabulary and ML is the structure over which L-constraints will be interpreted. The models of temporal constraint databases and indefinite temporal constraint databases can then be studied as instances of the last two of the above parameterized models. In the course of...

Abstract. Temporal reasoning started to be considered as a subject of study in artificial intelligence in the late ’70s. Since that several ways to represent and use temporal knowledge have been suggested. As a result of that there are several formalisms capable of coping with temporal notions in some way or other. They range from isolated proposals to complexsystems where the temporal aspect is used together with other important features for the task of modelling an intelligent agent. The purposes of this article are to summarize logic-based temporal reasoning research and give a glance on the different research tracks envisaging future lines of research. It is intended to be useful to those who need to be involved in systems having these characteristics and also an occasion to present newcomers some problems in the area that still wait for a solution.

The capability to represent and use concepts like time and events in computer science are essential to solve a wide class of problems characterized by the notion of change. Realtime, databases and multimedia are just a few of several areas which needs good tools to deal with time. Another area where this concepts are essential is arti cial intelligence because an agent must be able to reason about a dynamic environment.

this paper, I will survey a number of temporal formalisms and systems from Knowledge Representation and Databases. Work in these two areas is particularly relevant if one is interested in designing and implementing a Temporal Knowledge Base Management System (TKBMS). KBMSs have been recently proposed for the construction, maintenance and querying of large shared knowledge bases [BM86], [Ull88], [Ull89], [ST89]. Since so many practical problems involve temporal reasoning, it is an interesting reasearch problem to design and implement a TKBMS which can be used for storing and retrieving large amounts of knowledge about these problems. For example, a job-shop scheduling system like ISIS [FS84], [FM86] could take advantage of a TKBMS for storing knowledge about orders, products, resources and schedules. This knowledge could be shared between schedulers and plant staff. A TKBMS would also be useful as a component of a medical information system used for recording and analyzing symptoms, diseases and their effects on patients over time [WBW86]. To keep the rest of the discussion in perspective, I will now present a number of requirements which must be met by a TKBMS