This Festschrift volume has been published in honor ofFrank de Boer, on the occasion of his 60th birthday.Frank S. For a while, he also liked failures, especially in semantics, andoptimistically concluded with the failure of failures.

Program Verification: to Err is Human.- Fond (and Frank) Memories of Frank.- Warmest Congratulations, Frank.- Conformance Checking of Real-Time Models: Symbolic Execution vs. Bounded Model Checking.- Resource Analysis of Distributed Systems.- Comparing Trace Expressions and Linear Temporal Logic for Runtime Verification.- Proper Protocol.- A Compositional Approach to the Verification of Hybrid Systems.- Array Abstraction with Symbolic Pivots.- Modeling Role-Based Systems with Exogenous Coordination.- Vats: A Safe, Reactive Storage Abstraction.- Denotational and Operational Preciseness of Subtyping: A Roadmap.- A Sound and Complete Hoare Logic for Dynamically-Typed, Object-Oriented Programs.- Self-Reconfiguring Microservices.- Statically and Dynamically Verifiable SLA metrics.- Effectively Eliminating Auxiliaries.- Towards a Proof Method for Paradigm.- Toward a Formal Foundation for Time Travel in Stories and Games.- Industrial Application of Formal Models Generated from Domain SpecificLanguages.- Formal Verification of Open Normative Multi-Agent System.- Moessner’s Theorem: An Exercise in Coinductive Reasoning in Coq.- Towards a Kool Future.- On the Expressiveness of Synchronization in Component Deployment.- Characterisation of Simulation by Probabilistic Testing.- On Time Actors.- A Small-Step Semantics of a Concurrent Calculus with Goroutines and Deferred Functions.- Quicksort Revisited - Verifying Alternative Versions of Quicksort.

Contains refereed papers dedicated to Frank de Boer and to his work Collects a number of papers by Frank's collaborators over the years presenting a broad range of topics reflecting Frank's versatility Addresses a large diversity of topics from formal methods and theoretical computer science, such as logic and constraint programming; deductive proof systems, soundness, and completeness; semantics, compositionality, and full abstraction; process algebra and decidability; multithreading and actor-based concurrency; agent programming, ontologies, and modal logic; real-time systems, timed automata, and schedulability; enterprise architectures, choreography, and coordination; testing and runtime monitoring; and cloud computing and service level agreements Includes supplementary material: sn.pub/extras