Constitutes the refereed proceedings of the 14th International Conference on Logic for Programming, Artificial Intelligence, and Reasoning, LPAR 2007, held in Yerevan, Armenia, October 15-19, 2007. This book presents 36 revised full papers together with 15 short papers and 3 invited talks that were reviewed and selected from 78 submissions.

From Hilbert’s Program to a Logic Toolbox.- On the Notion of Vacuous Truth.- Whatever Happened to Deductive Question Answering?.- Decidable Fragments of Many-Sorted Logic.- One-Pass Tableaux for Computation Tree Logic.- Extending a Resolution Prover for Inequalities on Elementary Functions.- Model Checking the First-Order Fragment of Higher-Order Fixpoint Logic.- Monadic Fragments of Gödel Logics: Decidability and Undecidability Results.- Least and Greatest Fixed Points in Linear Logic.- The Semantics of Consistency and Trust in Peer Data Exchange Systems.- Completeness and Decidability in Sequence Logic.- HORPO with Computability Closure: A Reconstruction.- Zenon: An Extensible Automated Theorem Prover Producing Checkable Proofs.- Matching in Hybrid Terminologies.- Verifying Cryptographic Protocols with Subterms Constraints.- Deciding Knowledge in Security Protocols for Monoidal Equational Theories.- Mechanized Verification of CPS Transformations.- Operational and Epistemic Approaches to Protocol Analysis: Bridging the Gap.- Protocol Verification Via Rigid/Flexible Resolution.- Preferential Description Logics.- On Two Extensions of Abstract Categorial Grammars.- Why Would You Trust B?.- How Many Legs Do I Have? Non-Simple Roles in Number Restrictions Revisited.- On Finite Satisfiability of the Guarded Fragment with Equivalence or Transitive Guards.- Data Complexity in the Family of Description Logics.- An Extension of the Knuth-Bendix Ordering with LPO-Like Properties.- Retractile Proof Nets of the Purely Multiplicative and Additive Fragment of Linear Logic.- Integrating Inductive Definitions in SAT.- The Separation Theorem for Differential Interaction Nets.- Complexity of Planning in Action Formalisms Based on Description Logics.- Faster Phylogenetic Inferencewith MXG.- Enriched ?–Calculus Pushdown Module Checking.- Approved Models for Normal Logic Programs.- Permutative Additives and Exponentials.- Algorithms for Propositional Model Counting.- Completeness for Flat Modal Fixpoint Logics.- : Decidable Non-monotonic Disjunctive Logic Programs with Function Symbols.- The Complexity of Temporal Logic with Until and Since over Ordinals.- ATP Cross-Verification of the Mizar MPTP Challenge Problems.