Invited Talks -- Building SMT-Based Software Model Checkers: An Experience Report -- Combining Nonmonotonic Knowledge Bases with External Sources -- Combining Description Logics, Description Graphs, and Rules -- Combining Equational Reasoning -- Technical Papers -- Superposition Modulo Linear Arithmetic SUP(LA) -- Unification Modulo Homomorphic Encryption -- Argument Filterings and Usable Rules for Simply Typed Dependency Pairs -- DL-Lite with Temporalised Concepts, Rigid Axioms and Roles -- Runtime Verification Using a Temporal Description Logic -- Axiomatization and Completeness of Lexicographic Products of Modal Logics -- Automating Theories in Intuitionistic Logic -- Taming the Complexity of Temporal Epistemic Reasoning -- Putting ABox Updates into Action -- A Declarative Agent Programming Language Based on Action Theories -- Termination Modulo Combinations of Equational Theories -- Combinations of Theories for Decidable Fragments of First-Order Logic -- Products of Modal Logics with Diagonal Constant Lacking the Finite Model Property -- Improving Coq Propositional Reasoning Using a Lazy CNF Conversion Scheme -- Combining Instance Generation and Resolution -- Data Structures with Arithmetic Constraints: A Non-disjoint Combination -- Efficient Combination of Decision Procedures for MUS Computation -- Learning to Integrate Deduction and Search in Reasoning about Quantified Boolean Formulas -- Combining Theories with Shared Set Operations.

This book constitutes the refereed proceedings of the 7th International Symposium on Frontiers of Combining Systems, FroCoS 2007, held in Trento, Italy, September 16-18, 2009. The 20 revised full papers presented were carefully reviewed and selected. The papers are organized in topical sections on combinations of logics, theories, and decision procedures; constraint solving and programming; combination issues in rewriting and programming as well as in logical frameworks and theorem proving systems.