Invited Papers and Tutorial -- Integrating Logic Programming and Production Systems in Abductive Logic Programming Agents -- SILK: Higher Level Rules with Defaults and Semantic Scalability -- Uncertainty Reasoning for the Semantic Web -- Proof/Deduction Procedures -- A Preferential Tableaux Calculus for Circumscriptive -- A Reasoner for Simple Conceptual Logic Programs -- Search for More Declarativity -- Scalability -- Distributed Resolution for Expressive Ontology Networks -- Scalable Web Reasoning Using Logic Programming Techniques -- On the Ostensibly Silent ‘W’ in OWL 2 RL -- Uncertainty -- Answer Sets in a Fuzzy Equilibrium Logic -- Belief Logic Programming with Cyclic Dependencies -- A Minimal Deductive System for General Fuzzy RDF -- Knowledge Amalgamation and Querying -- An Efficient Method for Computing Alignment Diagnoses -- Paraconsistent Reasoning for OWL 2 -- A Formal Theory for Modular ERDF Ontologies -- The Perfect Match: RPL and RDF Rule Languages -- Rules for Decision Support and Production Systems -- A Hybrid Architecture for a Preoperative Decision Support System Using a Rule Engine and a Reasoner on a Clinical Ontology -- A Logic Based Approach to the Static Analysis of Production Systems.

This book constitutes the refereed proceedings of the Third International Conference on Web Reasoning and Rule Systems, RR 2009, held in Chantilly, VA, USA, in October 2009. The 15 revised full papers presented together with 3 invited papers were carefully reviewed and selected from 41 submissions. The papers address all current topics in Web reasoning and rule systems such as proof/deduction procedures, scalability, uncertainty, knowledge amalgamation and querying, and rules for decision support and production systems.