Inthe?eldofformalmethodsincomputerscience,concurrencytheoryisreceivinga constantlyincreasinginterest.Thisisespeciallytrueforprocessalgebra.Althoughit had been originally conceived as a means for reasoning about the semantics of c- current programs, process algebraic formalisms like CCS, CSP, ACP, ?-calculus, and their extensions (see, e.g., [154,119,112,22,155,181,30]) were soon used also for comprehendingfunctionaland nonfunctionalaspects of the behaviorof com- nicating concurrent systems. The scienti?c impact of process calculi and behavioral equivalences at the base of process algebra is witnessed not only by a very rich literature. It is in fact worth mentioningthe standardizationprocedurethat led to the developmentof the process algebraic language LOTOS [49], as well as the implementation of several modeling and analysis tools based on process algebra, like CWB [70] and CADP [93], some of which have been used in industrial case studies. Furthermore, process calculi and behavioral equivalencesare by now adopted in university-levelcourses to teach the foundations of concurrent programming as well as the model-driven design of concurrent, distributed, and mobile systems. Nevertheless, after 30 years since its introduction, process algebra is rarely adopted in the practice of software development. On the one hand, its technica- ties often obfuscate the way in which systems are modeled. As an example, if a process term comprises numerous occurrences of the parallel composition operator, it is hard to understand the communicationscheme among the varioussubterms. On the other hand, process algebra is perceived as being dif?cult to learn and use by practitioners, as it is not close enough to the way they think of software systems.

Inthe?eldofformalmethodsincomputerscience,concurrencytheoryisreceivinga constantlyincreasinginterest.Thisisespeciallytrueforprocessalgebra.Althoughit had been originally conceived as a means for reasoning about the semantics of c- current programs, process algebraic formalisms like CCS, CSP, ACP, ?-calculus, and their extensions (see, e.g., [154,119,112,22,155,181,30]) were soon used also for comprehendingfunctionaland nonfunctionalaspects of the behaviorof com- nicating concurrent systems. The scienti?c impact of process calculi and behavioral equivalences at the base of process algebra is witnessed not only by a very rich literature. It is in fact worth mentioningthe standardizationprocedurethat led to the developmentof the process algebraic language LOTOS [49], as well as the implementation of several modeling and analysis tools based on process algebra, like CWB [70] and CADP [93], some of which have been used in industrial case studies. Furthermore, process calculi and behavioral equivalencesare by now adopted in university-levelcourses to teach the foundations of concurrent programming as well as the model-driven design of concurrent, distributed, and mobile systems. Nevertheless, after 30 years since its introduction, process algebra is rarely adopted in the practice of software development. On the one hand, its technica- ties often obfuscate the way in which systems are modeled. As an example, if a process term comprises numerous occurrences of the parallel composition operator, it is hard to understand the communicationscheme among the varioussubterms. On the other hand, process algebra is perceived as being dif?cult to learn and use by practitioners, as it is not close enough to the way they think of software systems.

A large class of computing systems can be speci?ed and veri?ed by abstracting away from the temporal aspects of their behavior. Inreal-timesystems,instead, time issues become essential. Their correctness depends not only on which - tions they can perform, but also on the action execution time. Due to their importance and design challenges, real-time systems have attracted the att- tion of a considerable number of computer scientists and engineers from various research areas. This volume collects a set of papers accompanying the lectures of the fourth edition of theInternational School on Formal Methods for the Design of C- puter,Communication andSoftware Systems (SFM). The school addressed the use of formal methods in computer science as a prominent approach to the r- orous design of computer, communication and software systems. The main aim of the SFM series is to o?er a good spectrum of current research in foundations as well as applications of formal methods, which can be of help for graduate students and young researchers who intend to approach the ?eld. SFM-04:RT was devoted to real-time systems. It covered formal models and languagesforthespeci?cation,modeling,analysis,andveri? cationoftheseti- critical systems, the expressiveness of such models and languages, as well as supporting tools and related applications in di?erent domains.

This volume was published in honor of Rocco De Nicola's 65th birthday. The Festschrift volume contains 27 papers written by close collaborators and friends of Rocco De Nicola and was presented to Rocco on the 1st of July 2019 during a two-day symposium held in Lucca, Italy. The papers present many research ideas that have been influenced by Rocco's work. They testify his intellectual curiosity, versatility and tireless research activity, and provide an overview of further developments to come. The volume consists of six sections. The first one contains a laudation illustrating the distinguished career and the main scientific contributions by Rocco and a witness of working experiences with Rocco. The remaining five sections comprise scientific papers related to specific research interests of Rocco and are ordered according to his scientific evolution: Observational Semantics; Logics and Types; Coordination Models and Languages; Distributed Systems Modelling; Security.