Constitutes the proceedings of the 8th International Conference on Logic Programming and Nonmonotonic Reasoning, LPNMR 2005. This book contains topics addressing semantics of languages; relationships between formalisms; complexity and expressive power; software engineering, decision making, and other domains; and more.

Invited Papers.- Nonmonotonic Reasoning in FLORA-2.- Data Integration and Answer Set Programming.- Halo I: A Controlled Experiment for Large Scale Knowledge Base Development.- ASP Foundations.- Unfounded Sets for Disjunctive Logic Programs with Arbitrary Aggregates.- Loops: Relevant or Redundant?.- Approximating Answer Sets of Unitary Lifschitz-Woo Programs.- On Modular Translations and Strong Equivalence.- ASP Extensions.- Guarded Open Answer Set Programming.- External Sources of Computation for Answer Set Solvers.- Answer Sets for Propositional Theories.- Applications.- An ID-Logic Formalization of the Composition of Autonomous Databases.- On the Local Closed-World Assumption of Data-Sources.- Computing Dialectical Trees Efficiently in Possibilistic Defeasible Logic Programming.- Actions and Causations.- An Approximation of Action Theories of and Its Application to Conformant Planning.- Game-Theoretic Reasoning About Actions in Nonmonotonic Causal Theories.- Some Logical Properties of Nonmonotonic Causal Theories.- odular-?: An Elaboration Tolerant Approach to the Ramification and Qualification Problems.- Algorithms and Computation.- Platypus: A Platform for Distributed Answer Set Solving.- Solving Hard ASP Programs Efficiently.- Mode-Directed Fixed Point Computation.- Lookahead in Smodels Compared to Local Consistencies in CSP.- Foundations.- Nested Epistemic Logic Programs.- An Algebraic Account of Modularity in ID-Logic.- Default Reasoning with Preference Within Only Knowing Logic.- Semantics.- A Social Semantics for Multi-agent Systems.- Revisiting the Semantics of Interval Probabilistic Logic Programs.- Routley Semantics for Answer Sets.- The Well Supported Semantics for Multidimensional Dynamic Logic Programs.- Application Track.- Application ofSmodels in Quartet Based Phylogeny Construction.- Using Answer Set Programming for a Decision Support System.- Data Integration: a Challenging ASP Application.- Abduction and Preferences in Linguistics.- Inference of Gene Relations from Microarray Data by Abduction.- System Track.- nomore: A System for Computing Preferred Answer Sets.- Integrating an Answer Set Solver into Prolog: - .- circ2dlp — Translating Circumscription into Disjunctive Logic Programming.- Pbmodels — Software to Compute Stable Models by Pseudoboolean Solvers.- KMonitor– A Tool for Monitoring Plan Execution in Action Theories.- The nomore++ System.- Smodels A — A System for Computing Answer Sets of Logic Programs with Aggregates.- A DLP System with Object-Oriented Features.- Testing Strong Equivalence of Datalog Programs – Implementation and Examples.- SELP – A System for Studying Strong Equivalence Between Logic Programs.- cmodels – SAT-Based Disjunctive Answer Set Solver.