Jan Chomicki – författare

The designers and users of present-day information systems deal with more and more complex applications that have to meet stringent quality requirements. In this context, logic offers a wide variety of formalisms that can be applied to the specification, analysis, and prototype implementation of information systems. Such formalisms, for example, temporal logic, provide a sound semantic basis for further extensions and for the development of practical database languages. This text addresses novel applications of logical frameworks to the problems of database integrity and dynamics, handling time and change, concurrency, incomplete information, data modelling, and property inheritance. Each topic is discussed by different researchers in the field. The work is suitable as a secondary text for a graduate level course on Databases and Information Systems, and as a reference for researchers and practitioners in industry.

Time is ubiquitous in information systems. Almost every enterprise faces the problem of its data becoming out of date. However, such data is often valu­ able, so it should be archived and some means to access it should be provided. Also, some data may be inherently historical, e.g., medical, cadastral, or ju­ dicial records. Temporal databases provide a uniform and systematic way of dealing with historical data. Many languages have been proposed for tem­ poral databases, among others temporal logic. Temporal logic combines ab­ stract, formal semantics with the amenability to efficient implementation. This chapter shows how temporal logic can be used in temporal database applica­ tions. Rather than presenting new results, we report on recent developments and survey the field in a systematic way using a unified formal framework [GHR94; Ch094]. The handbook [GHR94] is a comprehensive reference on mathematical foundations of temporal logic. In this chapter we study how temporal logic is used as a query and integrity constraint language. Consequently, model-theoretic notions, particularly for­ mula satisfaction, are of primary interest. Axiomatic systems and proof meth­ ods for temporal logic [GHR94] have found so far relatively few applications in the context of information systems. Moreover, one needs to bear in mind that for the standard linearly-ordered time domains temporal logic is not re­ cursively axiomatizable [GHR94]' so recursive axiomatizations are by necessity incomplete.

In this era of heterogeneous and distributed data sources, ranging from semistructured documents to knowledge about coordination processes or workflows, logic provides a rich set of tools and techniques with which to address the questions of how to represent, query and reason about complex data.This book provides a state-of-the-art overview of research on the application of logic-based methods to information systems, covering highly topical and emerging fields: XML programming and querying, intelligent agents, workflow modeling and verification, data integration, temporal and dynamic information, data mining, authorization, and security. It provides both scientists and graduate students with a wealth of material and references for their own research and education.