The papers in this collection were presented at the 7th International Con- rence on Logic Programming and Nonmonotonic Reasoning (LPNMR-7) in Fort Lauderdale, Florida, USA, during January 6 8, 2004. The previous meetings in this series were held in Washington, DC, USA (1991), Lisbon, Portugal (1993), Lexington, USA (1995), Dagstuhl, Germany (1997), El Paso, USA (1999), and Vienna, Austria (2001). LPNMR conferences are a forum for exchanging ideas on declarative logic programming, nonmonotonic reasoning and knowledge representation. In the 1980sresearchersworkingintheareaofnonmonotonicreasoningdiscoveredthat their formalisms could be used to describe the behavior of negation as failure in Prolog,andthe?rstLPNMRmeetingwasconvenedforthepurposeofdiscussing thisrelationship.Thisworkhasledtothecreationoflogicprogrammingsystems of a new kind, answer set solvers, and to the emergence of a new approach to solving combinatorial search problems, called answer set programming. The highlights of LPNMR-7 were three invited talks, given by Rina Dechter (University of California, Irvine), Henry Kautz (University of Washington) and Torsten Schaub (University of Potsdam). The program also included 24 regular papers selected after a rigorous review process, 8 system descriptions, and 2 panels. We would like to thank the Program Committee members and additional reviewers for careful, unbiased evaluation of the submitted papers. We are also grateful to Paolo Ferraris for help with publicizing the Call for Papers, to Fred Ho?man for help with local organizational matters, and to Matti J arvisalo for help with the organization of the electronic Program Committee meeting.

Inhalt
Invited Papers.- Constraints and Probabilistic Networks: A Look At The Interface.- Toward A Universal Inference Engine.- Towards Systematic Benchmarking in Answer Set Programming: The Dagstuhl Initiative.- Regular Papers.- Semantics for Dynamic Logic Programming: A Principle-Based Approach.- Probabilistic Reasoning With Answer Sets.- Answer Sets: From Constraint Programming Towards Qualitative Optimization.- A Logic of Non-monotone Inductive Definitions and Its Modularity Properties.- Reasoning About Actions and Change in Answer Set Programming.- Almost Definite Causal Theories.- Simplifying Logic Programs Under Uniform and Strong Equivalence.- Towards Automated Integration of Guess and Check Programs in Answer Set Programming.- Towards Automated Integration of Guess and Check Programs in Answer Set Programming.- Graphs and Colorings for Answer Set Programming: Abridged Report.- Nondefinite vs. Definite Causal Theories.- Logic Programs With Monotone Cardinality Atoms.- Set Constraints in Logic Programming.- Verifying the Equivalence of Logic Programs in the Disjunctive Case.- Uniform Equivalence for Equilibrium Logic and Logic Programs.- Partial Stable Models for Logic Programs with Aggregates.- Improving the Model Generation/Checking Interplay to Enhance the Evaluation of Disjunctive Programs.- Using Criticalities as a Heuristic for Answer Set Programming.- Planning with Preferences Using Logic Programming.- Planning with Sensing Actions and Incomplete Information Using Logic Programming.- Deduction in Ontologies via ASP.- Strong Equivalence for Causal Theories.- Answer Set Programming with Clause Learning.- Properties of Iterated Multiple Belief Revision.- System Descriptions.- System Description: DLV with Aggregates.- GNT A Solver for Disjunctive Logic Programs.-LPEQ and DLPEQ Translators for Automated Equivalence Testing of Logic Programs.- DLV DB : Bridging the Gap between ASP Systems and DBMSs.- Cmodels-2: SAT-based Answer Set Solver Enhanced to Non-tight Programs.- WSAT(CC) A Fast Local-Search ASP Solver.- Smodels with CLPA Treatment of Aggregates in ASP.- nlp: A Compiler for Nested Logic Programming.