This volume contains the proceedings of the tenth annual Symposium on Theoretical Aspects of Computer Science (STACS '93), held in W}rzburg, February 25-27, 1993. The STACS symposia are held alternately in Germany and France, and organized jointly by the Special Interest Group for Theoretical Computer Science of the Gesellschaft f}r Informatik (GI) and theSpecial Interest Group for Applied Mathematics of the Association Francaise des Sciences et Technologies de l'Information et des Syst mes (afcet). The volume includes the three invited talks which opened the three days of the symposium: "Causal and distributed semantics for concurrent processes" (I. Castellani), "Parallel architectures: design and efficient use" (B. Monien et al.), and "Transparent proofs" (L. Babai). The selection of contributed papers is organized into parts on: computational complexity, logic in computer science, efficient algorithms, parallel and distributed computation, language theory, computational geometry, automata theory, semantics and logic of programming languages, automata theory and logic, circuit complexity, omega-automata, non-classical complexity, learning theory and cryptography, and systems.

This volume constitutes the proceedings of the 11th annual Symposium on Theoretical Aspects of Computer Science (STACS '94), held in Caen, France, February 24-26, 1994. Besides three prominent invited papers, the proceedings contains 60 accepted contributions chosen by the international program committee during a highly competitive reviewing process from a total of 234 submissions for 38 countries. The volume competently represents most areas of theoretical computer science with a certain emphasis on (parallel) algorithms and complexity.

Symposium on Algorithms (ESA '93), held in Bad Honnef, near Boon, in Germany, September 30 - October 2, 1993. The symposium is intended to launchan annual series of international conferences, held in early fall, covering the field of algorithms. Within the scope of the symposium lies all research on algorithms, theoretical as well as applied, that is carried out in the fields of computer science and discrete applied mathematics. The symposium aims to cater to both of these research communities and to intensify the exchange between them. The volume contains 35 contributed papers selected from 101 proposals submitted in response to the call for papers, as well as three invited lectures: "Evolution of an algorithm" by Michael Paterson, "Complexity of disjoint paths problems in planar graphs" by Alexander Schrijver, and "Sequence comparison and statistical significance in molecular biology" by Michael S. Waterman.

This volume is the proceedings of the Ninth International Conference on the Mathematical Foundations of Programming Semantics, held in New Orleans in April 1993. The focus of the conference series is the semantics of programming languages and the mathematics which supports the study of the semantics. The semantics is basically denotation. The mathematics may be classified as category theory, lattice theory, or logic. Recent conferences and workshops have increasingly emphasized applications of the semantics and mathematics. The study of the semantics develops with the mathematics and the mathematics is inspired by the applications in semantics. The volume presents current research in denotational semantics and applications of category theory, logic, and lattice theory to semantics.

The CRYPTO ’93 conference was sponsored by the International Association for Cryptologic Research (IACR) and Bell-Northern Research (a subsidiary of Northern Telecom), in co-operation with the IEEE Computer Society Technical Committee. It took place at the University of California, Santa Barbara, from August 22-26, 1993. This was the thirteenth annual CRYPTO conference, all of which have been held at UCSB. The conference was very enjoyable and ran very of the General Chair, Paul Van Oorschot. smoothly, largely due to the efforts It was a pleasure working with Paul throughout the months leading up to the conference. There were 136 submitted papers which were considered by the Program Committee. Of these, 38 were selected for presentation at the conference. There was also one invited talk at the conference, presented by Miles Smid, the title of which was “A Status Report On the Federal Government Key Escrow System.” The conference also included the customary Rump Session, which was presided over by Whit Diffie in his usual inimitable fashion. Thanks again to Whit for organizing and running the Rump session. This year, the Rump Session included an interesting and lively panel discussion on issues pertaining to key escrowing. Those taking part were W. Diffie, J. Gilmore, S. Goldwasser, M. Hellman, A. Herzberg, S. Micali, R. Rueppel, G. Simmons and D. Weitzner.

This volume contains the proceedings of the 14th International Conference onApplication and Theory of Petri Nets. The aim of the Petri net conferences is to create a forum for discussing progress in the application and theory of Petri nets. Typically, the conferences have 150-200 participants, one third of whom come from industry, while the rest are from universities and research institutes. The volume includes three invited papers, "Modeling and enactment of workflow systems" (C.A. Ellis, G.J. Nutt), "Interleaving functional and performance structural analysis of net models" (M. Silva), and "FSPNs: fluid stochastic Petri nets" (K.S. Trivedi, V.G. Kulkarni), together with 26 full papers (selected from 102 submissions) and 6 project papers.

LPAR is an international conference series aimed at bringing together researchers interested in logic programming and automated reasoning. The research in logic programming grew out of the research in automated reasoning in the early 1970s. Later, the implementation techniques known from logic programming were used in implementing theorem proving systems. Results from both fields applied to deductive databases. This volume contains the proceedings of LPAR '93, which was organized by the Russian Association for Logic Programming. The volume contains 35 contributed papers selected from 84 submissions, together with an invited paper by Peter Wegner entitled "Reasoning versus modeling in computer science".

Since their inception, the Perspectives in Logic and Lecture Notes in Logic series have published seminal works by leading logicians. Many of the original books in the series have been unavailable for years, but they are now in print once again. This volume, the twelfth publication in the Lecture Notes in Logic series, collects the proceedings of the European Summer Meeting of the Association of Symbolic Logic, held at the University of the Basque Country, San Sebastian in July 1996. The main topics were model theory, proof theory, recursion and complexity theory, models of arithmetic, logic for artificial intelligence, formal semantics of natural language, and philosophy of contemporary logic. The volume includes eleven papers from pre-eminent researchers in mathematical logic.

For more than a decade, Foundations of Software Technology and Theoretical Computer Science Conferences have been providing an annual forum for the presentation of new research results in India and abroad. This year, 119 papers from 20 countries were submitted. Each paper was reviewed by at least three reviewers, and 33 papers were selected for presentation and included in this volume, grouped into parts on type theory, parallel algorithms, term rewriting, logic and constraint logic programming, computational geometry and complexity, software technology, concurrency, distributed algorithms, and algorithms and learning theory. Also included in the volume are the five invited papers presented at theconference.