This book constitutes the refereed proceedings of the 13th Brazilian Symposium on Artificial Intelligence, SBIA '96, held in Curitiba, Brazil, in October 1996.The 21 revised full papers presented were carefully selected from a total of 66 submissions; also included are one-page abstracts of invited talks and poster presentations. Besides a strong Brazilian component, the majority of contributing authors are well-known researchers from abroad. The papers are organized in topical sections on nonmonotonic reasoning, planning, learning and heuristic search, distributed AI and multi-agent systems, genetic algorithms, natural language processing, vision and AI applications, and logic programming.

An argumentation based framework for defeasible and qualitative reasoning.- Well-behaved IDL theories.- Epistemic conditional logics.- A Hybrid Formal Theory of plan recognition and its implementation.- Algorithms ? for ?-standard state graphs: Results about termination and admissibility.- Regression by classification.- A generic model of cognitive agent to develop open systems.- Coordination among individually-motivated agents: An evolutionary approach.- Adaptive Hierarchical Censored Production Rule-based system: A genetic algorithm approach.- Finding optimal representations using the crossover correlation coefficient.- An evolutionary algorithm for resource-constrained project scheduling and multiple execution modes.- Evaluating the robustness and scalability of revision-based natural language generation.- Semi-automatic anaphora resolution in portable natural language interfaces.- A discourse model for gist preservation.- Iterative curve organisation with the EM algorithm.- Model-Based pose proposal for 2-D object recognition.- TARCA - An integrated system for diagnosis and treatment of cardiac arrhythmias.- Intelligent Distributed Environmental Decision Support System.- Object-oriented algorithm for combining dichotomic belief functions.- Automatic bottom-up analysis and transformation of logic programs.- A temporal extension to the Parsimonious Covering Theory.- Biological inspirations in neural network implementations of Autonomous Agents.- Intelligent Tutoring Systems modelled through the mental states.- Fundamentals of fuzzy logic and its hardware implementation.- Status & challenges for coordination technology: An AI perspective.- Combining natural language understanding and information retrieval for flexible hypertext navigation.- Numerical models forthe treatment of imperfect information in knowledge-based systems.- Intelligent Tutoring Systems: Functional approach x agents approach.- The case-based reasoning paradigm: perspective, technology and impacts.- Qualitative models for interactive articulated learning environments.- H-computation.- Is computer vision still AI?.- Fuzzy robotics and fuzzy image understanding.- Toward a theory of molecular computing.