The present volume has its origin in a meeting of philosophers, linguists and cognitive scientists that was held at Umea University, Sweden, September 24-26, 1993. The meeting was organized by the Department of Philosophy in cooperation with the Department of Linguistics, and it was called UmLLI-93, the Umea Colloquium on Dynamic Approaches in Logic, Language and Information. The papers published here are considerably expanded and revised versions of talks presented by invited speakers at this colloquium. The papers included here fall into three broad categories. In the first part of the book, Action, we have collected papers that concern the formal theory of action, the logic of nonns, and the theory of rational decision. The papers in the second part, Belief Change, concern the theory of belief dynamics in the tradition of Alchourr6n, Gardenfors and Makinson. The third part, Cognition, concerns abstract questions about knowledge and truth as well'as more concrete questions about the usefuleness and tractability of various graphic representations of infonnation. An additional and important topic of the colloquium concerned logical approaches to natural language. For the sake of the thematic unity of this book, and its appearance in the series Trends in logic, the colloquium papers related to language are not included here, but some of these contributions will appear in the philosophical journal Theoria.

The logic of information flow has applications in both computer science and natural language processing and is a growing area within mathematical and philosophical logic.

The Logic of Connective Action shows how political action is coordinated and power is organized in communication-based networks, and what political outcomes may result.

Logic programming enjoys a privileged position. It is firmly rooted in mathematical logic, yet it is also immensely practical, as a growing number of users in universities, research institutes, and industry are realizing. Logic programming languages, specifically Prolog, have turned out to be ideal as prototyping and application development languages. This volume presents the proceedings of the Second Logic Programming Summer School, LPSS'92. The First Logic Programming Summer School, LPSS '90, addressed the theoretical foundations of logic programming. This volume focuses onthe relationship between theory and practice, and on practical applications. The introduction to the volume is by R. Kowalski, one of the pioneers in the field. The following papers are organized into sections on constraint logic programming, deductive databases and expert systems, processing of natural and formal languages, software engineering, and education.

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.

This second volume in the series Logic, Epistemology, and the Unity of Science brings a pragmatic perspective to the discussion of the unity of science. Contemporary philosophy and cognitive science increasingly acknowledge the systematic interrelation of language, thought and action. The principal function of language is to enable speakers to communicate their intentions to others, to respond flexibly in a social context and to act cooperatively in the world. This book will contribute to our understanding of this dynamic process by clearly presenting and discussing the most important hypotheses, issues and theories in philosophical and logical study of language, thought and action. Among the fundamental issues discussed are the rationality and freedom of agents, theoretical and practical reasoning, individual and collective attitudes and actions, the nature of cooperation and communication, the construction and conditions of adequacy of scientific theories, propositional contents and their truth conditions, illocutionary force, time, aspect and presupposition in meaning, speech acts within dialogue, the dialogical approach to logic and the structure of dialogues and other language games, as well as formal methods needed in logic or artificial intelligence to account for choice, paradoxes, uncertainty and imprecision. This volume contains major contributions by leading logicians, analytic philosophers, linguists and computer scientists. It will be of interest to graduate students and researchers from philosophy, logic, linguistics, cognitive science and artificial intelligence. There is no comparable survey in the existing literature.