Preface Volume 67

AbstractThis volume contains the Proceedings of the 9th Workshop on Logic, Language, Information and Computation (WoLLIC'2002). The Workshop was held in Rio de Janeiro, Brazil from July 30 to August 2, 2002, in the campus of the Pontifícia Universidade Católica do Rio de Janeiro (PUC-Rio).WoLLIC is a series of workshops which started in 1994 with the aim of fostering interdisciplinary research in pure and applied logic. The idea is to have a forum which is large enough in the number of possible interactions between logic and the sciences related to information and computation, and yet is small enough to allow for concrete and useful interaction among participants. Previous versions were held at: Recife (Pernambuco, Brazil) in 1994 and 1995; Salvador (Bahia, Brazil) in 1996; Fortaleza (Ceará, Brazil) in 1997; São Paulo (Brazil) in 1998; Itatiaia (Rio de Janeiro, Brazil) in 1999; Natal (Rio Grande do Norte) in 2000; Brasília (Distrito Federal, Brazil) in 2001. [new] Scientific sponsorship comes from the Interest Group in Pure and Applied Logics (IGPL), the European Association for Logic, Language and Information (FoLLI), the Association for Symbolic Logic (ASL), the Sociedade Brasileira de Computação (SBC), and the Sociedade Brasileira de Lógica (SBL).[end new] Scientific sponsorship comes from the Interest Group in Pure and Applied Logics (IGPL), the European Association for Logic, Language and Information (FoLLI), the Association for Symbolic Logic (ASL), the Sociedade Brasileira de Computação (SBC), and the Sociedade Brasileira de Lógica (SBL). Funding was kindly given by: (i) CNPq (Conselho Nacional de Desenvolvimento Científico e Tecnológico, the scientific and technological development council of the Brazilian Ministério da Ciência e Tecnologia) (grant 451491/2002-5); (ii) CAPES (Fundação Coordenação de Apoio ao Aperfeiçoamento de Pessoal de Nível Superior, a Foundation for the Development of Higher-Education under the Brazilian Ministério da Educação e do Desporto) (grant PAEP0169/02-1); (iii) PUC-Rio (Pontifícia Universidade Católica do Rio de Janeiro). Contributions were received in the form of short papers in all areas related to logic, language, information and computation, including: pure logical systems, proof theory, model theory, algebraic logic, type theory, category theory, constructive mathematics, lambda and combinatorial calculi, program logic and program semantics, logics and models of concurrency, logic and complexity theory, proof complexity, foundations of cryptography (zero-knowledge proofs), descriptive complexity, nonclassical logics, nonmonotonic logic, logic and language, discourse representation, logic and artificial intelligence, automated deduction, foundations of logic programming, logic and computation, and logic engineering.Apart from the contributed papers (14), and the invited talks (6), the programme includes 6 tutorial lectures: •Some model theory of ordered structures by Ricardo Bianconi (Departamento de Matemática Pura, Instituto de Matemática e Estatística, Universidade de São Paulo, Brazil)•Computing with Real Numbers by Felipe Cucker (Department of Mathematics, City University of Hong Kong, People's Republic of China)•Model Checking Games by Erich Grädel (Mathematische Grundlagen der Informatik, RWTH Aachen, Germany)•The Metalanguage Lambda Prolog and its Implementation by Gopalan Nadathur (University of Minnesota, USA)•Automata theory and logic by Igor Walukiewicz (Bordeaux University, France)•States of Knowledge (Tutorial) by Rohit Parikh (Department of Computer and Information Science, Brooklyn College, City University of New York, USA)All papers in the volume were reviewed by the program committee consisting, besides editor, of Mauricio Ayala-Rincón(Department of Mathematics, Universidade de Brasília, Brazil)Mario Benevides(Institute of Mathematics, Universidade Federal do Rio de Janeiro, Brazil)Anuj Dawar(Computer Laboratory, Cambridge University, England)Philippe de Groote(LORIA, France)Roger Maddux(Department of Mathematics, Iowa State University, USA)Toniann Pitassi(Department of Computer Science, Toronto University, Canada)Bruno Poizat(Institut Girard Desargues, Université Claude Bernard Lyon I, France)Alberto Policriti(Department of Mathematics and Informatics, Università di Udine, Italy)Glynn Winskel(Computer Laboratory, Cambridge University, England)The organising committee consisted, besides editor, of Edward Hermann Haeusler(Department of Informatics, Pontifícia Universidade Católica do Rio de Janeiro, Brazil)Claus Akira Matsushigue(Institute of Mathematics and Statistics, Universidade de São Paulo, Brazil)Anjolina Grisi de Oliveira(Center of Informatics, Universidade Federal de Pernambuco, Brazil)Luiz Carlos Pereira(Department of Philosophy, Pontifícia Universidade Católica do Rio de Janeiro, Brazil)Ruy de Queiroz(Center of Informatics, Universidade Federal de Pernambuco, Brazil)Jorge Petrúcio Viana(Coordination of Postgraduate Programmes in Engineering and Systems, Universidade Federal do Rio de Janeiro, Brazil)The volume will be published as volume 67 in the series Electronic Notes in Theoretical Computer Science (ENTCS). This series is published electronically through the facilities of Elsevier Science B.V. and its auspices. The volumes in the ENTCS series can be accessed at the URL http://www.elsevier.nl/locate/entcsA printed version of the current volume is distributed to the participants at the workshop in Rio de Janeiro.We are very grateful to the following persons, whose help has been crucial for the success of WoLLIC'2002: Mike Mislove, one of the Managing Editors of the ENTCS series, for his assistance with the use of the ENTCS style files; Thanks are also due to the Departments of Philosophy and Informatics of the Pontifícia Universidade Católica of Rio de Janeiro, which has provided the logistic support to the organising committee.July 26, 2002 Ruy de Queiro