Invited Talks -- A Formally Verified OS Kernel. Now What? -- Proof Assistants as Teaching Assistants: A View from the Trenches -- Proof Pearls -- A Certified Denotational Abstract Interpreter -- Using a First Order Logic to Verify That Some Set of Reals Has No Lesbegue Measure -- A New Foundation for Nominal Isabelle -- (Nominal) Unification by Recursive Descent with Triangular Substitutions -- A Formal Proof of a Necessary and Sufficient Condition for Deadlock-Free Adaptive Networks -- Regular Papers -- Extending Coq with Imperative Features and Its Application to SAT Verification -- A Tactic Language for Declarative Proofs -- Programming Language Techniques for Cryptographic Proofs -- Nitpick: A Counterexample Generator for Higher-Order Logic Based on a Relational Model Finder -- Formal Proof of a Wave Equation Resolution Scheme: The Method Error -- An Efficient Coq Tactic for Deciding Kleene Algebras -- Fast LCF-Style Proof Reconstruction for Z3 -- The Optimal Fixed Point Combinator -- Formal Study of Plane Delaunay Triangulation -- Reasoning with Higher-Order Abstract Syntax and Contexts: A Comparison -- A Trustworthy Monadic Formalization of the ARMv7 Instruction Set Architecture -- Automated Machine-Checked Hybrid System Safety Proofs -- Coverset Induction with Partiality and Subsorts: A Powerlist Case Study -- Case-Analysis for Rippling and Inductive Proof -- Importing HOL Light into Coq -- A Mechanized Translation from Higher-Order Logic to Set Theory -- The Isabelle Collections Framework -- Interactive Termination Proofs Using Termination Cores -- A Framework for Formal Verification of Compiler Optimizations -- On the Formalization of the Lebesgue Integration Theory in HOL -- From Total Store Order to Sequential Consistency: A Practical Reduction Theorem -- Equations: A Dependent Pattern-Matching Compiler -- A Mechanically Verified AIG-to-BDD Conversion Algorithm -- Inductive Consequences in the Calculus of Constructions -- Validating QBF Invalidity in HOL4 -- Rough Diamonds -- Higher-Order Abstract Syntax in Isabelle/HOL -- Separation Logic Adapted for Proofs by Rewriting -- Developing the Algebraic Hierarchy with Type Classes in Coq.