Logic and Agent Programming Languages -- Natural Models of Homotopy Type Theory (Abstract) -- Modelling Infinite Structures with Atoms -- Counting in SPARQL Property Paths: Perspectives from Theory and Practice -- Quantitative Approaches to Information Protection -- Perspectives of Dynamic Complexity -- Linear Time Proof Verification on N-Graphs: A Graph Theoretic Approach -- First Order Extensions of Residue Classes and Uniform Circuit Complexity -- Quantum Probabilistic Dyadic Second-Order Logic -- Structural Extensions of Display Calculi: A General Recipe -- The Same, Similar, or Just Completely Different? Equivalence for Argumentation in Light of Logic -- Boolean Dependence Logic and Partially-Ordered Connectives -- Extended Modal Dependence Logic EMDL -- Dependence Logic with Generalized Quantifiers: Axiomatizations -- Continuous Truth II: Reflections -- A Simple Separation Logic -- Independence in Database Relations -- Substructural Logic of Proofs -- Full Lambek Hyperdoctrine: Categorical Semantics for First-Order Substructural Logics -- A Finite Model Property for G¨odel Modal Logics -- Model Checking for Modal Dependence Logic: An Approach through Post’s Lattice -- Ockhamist Propositional Dynamic Logic: A Natural Link between PDL and CTL -- Information, Awareness and Substructural Logics.

Edited in collaboration with FoLLI, the Association of Logic, Language and Information this book constitutes the refereed proceedings of the 20th Workshop on Logic, Language, Information and Communication, WoLLIC 2013, held in Darmstadt, Germany, in August 2013. The 17 contributed papers presented  together with 6 invited lectures were carefully reviewed and selected from 30 submissions. The scope of the workshop spans the theoretical and practical aspects of formal logic, computing and programming theory, and natural language and reasoning.