The papers are organized in topical sections on knowledge representation, reasoning about actions, belief revision, theorem proving, argumentation, agents, decidability and complexity, updates, and preferences.

Invited Talks.- ‘On Being Informed’: Update Logics for Knowledge States.- Considerations on Updates of Logic Programs.- The Approach: Integrating Object Oriented Design and Formal Verification.- Semi-qualitative Reasoning about Distances: A Preliminary Report.- Regular Contributions.- Hybrid Probabilistic Logic Programs as Residuated Logic Programs.- Topo-distance: Measuring the Difference between Spatial Patterns.- An Abductive Mechanism for Natural Language Processing Based on Lambek Calculus.- Capturing Stationary and Regular Extensions with Reiter’s Extensions.- Representing the Process Semantics in the Event Calculus.- Declarative Formalization of Strategies for Action Selection: Applications to Planning.- An Algorithmic Approach to Recover Inconsistent Knowledge-Bases.- Acceptance Without Minimality.- Reduction Theorems for Boolean Formulas Using ?-Trees.- Simultaneous Rigid Sorted Unification.- Partially Adaptive Code Trees.- On Dialogue Systems with Speech Acts, Arguments, and Counterarguments.- Credulous and Sceptical Argument Games for Preferred Semantics.- A General Approach to Multi-agent Minimal Knowledge.- A Modal Logic for Network Topologies.- Avoiding Logical Omniscience by Using Subjective Situations.- Multi-agent Logic.- New Tractable Cases in Default Reasoning from Conditional Knowledge Bases.- Monodic Epistemic Predicate Logic.- Updates plus Preferences.- A Framework for Belief Update.- A Compilation of Brewka and Eiter’s Approach to Prioritization.- A Logic for Modeling Decision Making with Dynamic Preferences.