Invited Papers -- A Computational Logic Approach to Heterogenous Agent Systems -- Declarative Information Extraction, Web Crawling, and Recursive Wrapping with Lixto -- On The Complexity of Model Checking and Inference in Minimal Models -- Data Integration Needs Reasoning -- Nonmonotomic Inductive Logic Programming -- Regular Papers -- Strong Equivalence for Logic Programs and Default Theories (Made Easy) -- On the Effect of Default Negation on the Expressiveness of Disjunctive Rules -- On the Expressibility of Stable Logic Programming -- On the Relationship between Defeasible Logic and Well-Founded Semantics -- A Comparative Study of Well-Founded Semantics for Disjunctive Logic Programs -- Reasoning with Open Logic Programs -- Representation of Incomplete Knowledge by Induction of Default Theories -- Explicity Using Default Knowledge in Concept Learning: An Extended Description Logics Plus Strict and Default Rules -- Declarative Specification and Solution of Combinatorial Auctions Using Logic Programming -- Bounded LTL Model Checking with Stable Models -- Diagnosing Physical Systems in A-Prolog -- Planning with Different Forms of Domain-Dependent Control Knowledge — An Answer Set Programming Approach -- Encoding Solutions of the Frame Problem in Dynamic Logic -- ?-RES: Reasoning about Actions, Events and Observations -- Omega-Restricted Logic Programs -- Improving ASP Instantiators by Join-Ordering Methods -- Optimizing the Computation of Heuristics for Answer Set Programming Systems -- New Generation Systems for Non-monotonic Reasoning -- Algorithms for Computing X-Minimal Models -- Fixpoint Characterizations for Many-Valued Disjunctive Logic Programs with Probabilistic Semantics -- Multi-adjoint Logic Programming with Continous Semantics -- Multi-dimensional Dynamic Knowledge Representation -- Antitonic Logic Programs -- System Description -- A-system: Declarative Programming with Abduction -- An Update Front-End for Extended Logic Programs -- aspps — An Implementation of Answer-Set Programming with Propositional Schemata -- NoMoRe: A System for Non-Monotonic Reasoning under Answer Set Semantics -- plp: A Generic Compiler for Ordered Logic Programs -- Prototypes for Reasoning with Infinite Stable Models and Function Symbols -- psmodels: Stable Models Based on Pertinence -- System Description: DLV -- System Description: The DLVK Planning System -- The Smodels System -- The USA-Advisor: A Case Study in Answer Set Planning.