Synchronous languages have been designed for the unambiguous description of reactive real-time systems. Their key innovation is a clever abstraction from physical time to logical time, which allows programmers to separate the functional behavior from the real-time constraints of their programs. To this end, the execution of a synchronous program is divided into discrete reaction steps that correspond to the interaction of the reactive system with its environment. In every reaction step, new input values are read by the system and new output values are immediately computed as the reaction of the synchronous program. In the programmer's view, the computations of a reaction step are thereby performed in "zero time". This simplifies greatly the temporal reasonings, by providing ideal temporal primitives and deterministic semantics.

The use of synchronous languages in model-driven engineering has many advantages: For example, the parallel composition of synchronous programs that are triggered by the same clock is deterministic. For this reason, it is possible to replay once observed phenomena in simulation, and to avoid so-called Heisenbugs (when added code for testing changes the behavior of the system under test). Moreover, once hardware architectures are determined, the physical execution time of reaction steps can be estimated since, by construction of the languages, it is guaranteed that there are no data dependent loops within a reaction. Finally, due to precisely formulated semantics, all synchronous languages lend themselves well for formal analysis, in particular, formal verification. For all of these reasons, almost all digital hardware circuits are designed as synchronous circuits, and synchronous programming languages transfer these benefits to the software and hardware/software co-design.

However, the continuously growing complexity of applications pose new challenges, such as the de-synchronization of synchronous designs to allow the synthesis of globally asynchronous locally synchronous (GALS) or distributed systems. Moreover, the sound integration of synchronous, polychronous, and asynchronous, event- and time-triggered, or discrete and continuous systems is still a major challenge that requires further research. Also, the optimized code generation for and the design of appropriate multithreaded processor architectures is of growing interest.

This seminar aims to address these challenges, building on a strong and active community and expanding its scope into relevant related fields. It is an edition of the Synchronous Programming (SYNCHRON) workshops that is the yearly meeting place for the researchers in this exciting field. The SYNCHRON workshops started in 1993 at Schloss Dagstuhl, and we are proud to celebrate the 20-th edition of the workshop from November 17-22, 2013 again in Dagstuhl. During its nineteen years of existence, the workshop has evolved significantly: its scope has grown to expand to many languages and techniques that are not classically synchronous, but have been substantially influenced by the synchronous languages' attention to timing, mathematical rigor, and parallelism. Also, while many of the most senior synchronous language researchers are still active, many younger researchers have also entered the fray and have taken the field in new directions.

As typical for Dagstuhl Seminars, SYNCHRON is also an open forum without program selection or review process. It welcomes an international audience of students and researchers to present their latest ongoing work on the large spectrum of topics including for example programming language semantics, models of computation and communication, concurrency and scheduling theory, domain-specific languages, design methodologies like model-driven engineering, modeling and simulation, verification/analysis and validation, hardware/software synthesis, cyber-physical systems, code generation, tools, projects, case studies, and engineering practice of applying synchronous programming.

• Joaquin Aguado (Universität Bamberg, DE) [dblp]
• Mihail Asavoae (VERIMAG - Grenoble, FR) [dblp]
• Yu Bai (TU Kaiserslautern, DE) [dblp]
• Fernando Barros (University of Coimbra, PT) [dblp]
• Sanjoy Baruah (University of North Carolina at Chapel Hill, US) [dblp]
• Guillaume Baudart (ENS - Paris, FR) [dblp]
• Vagelis Bebelis (INRIA - Grenoble, FR) [dblp]
• Gérard Berry (INRIA Sophia Antipolis - Méditerranée, FR) [dblp]
• Nicolas Berthier (INRIA Rennes - Bretagne Atlantique, FR) [dblp]
• Timothy Bourke (ENS - Paris, FR & INRIA - Paris, FR) [dblp]
• David Broman (University of California - Berkeley, US) [dblp]
• Benoit Caillaud (INRIA Rennes - Bretagne Atlantique, FR) [dblp]
• Albert Cohen (ENS - Paris, FR) [dblp]
• Willem-Paul de Roever (Universität Kiel, DE) [dblp]
• Robert de Simone (INRIA Sophia Antipolis - Méditerranée, FR) [dblp]
• Gwenaël Delaval (University of Grenoble - LIG, FR) [dblp]
• Stephen A. Edwards (Columbia University - New York, US) [dblp]
• Peter A. Fritzson (Linköping University, SE) [dblp]
• Manuel Gesell (TU Kaiserslautern, DE) [dblp]
• Dan R. Ghica (University of Birmingham, GB) [dblp]
• Alain Girault (INRIA - Grenoble, FR) [dblp]
• Adrien Guatto (ENS - Paris, FR) [dblp]
• Nicolas Halbwachs (VERIMAG - Grenoble, FR) [dblp]
• Jun Inoue (ENS - Paris, FR) [dblp]
• Xian Li (TU Kaiserslautern, DE) [dblp]
• Gerald Lüttgen (Universität Bamberg, DE) [dblp]
• Antoine Madet (ENS - Paris, FR) [dblp]
• Frédéric Mallet (INRIA Sophia Antipolis - Méditerranée, FR) [dblp]
• Louis Mandel (College de France, Paris, FR) [dblp]
• Florence Maraninchi (VERIMAG - Grenoble, FR) [dblp]
• Eleftherios Matsikoudis (University of California - Berkeley, US) [dblp]
• Michael Mendler (Universität Bamberg, DE) [dblp]
• Christian Motika (Universität Kiel, DE) [dblp]
• Valentin Perrelle (IRT SystemX, FR) [dblp]
• John Plaice (UNSW - Sydney, AU) [dblp]
• Dumitru Potop-Butucaru (INRIA - Le Chesnay, FR) [dblp]
• Marc Pouzet (ENS - Paris, FR) [dblp]
• Pascal Raymond (VERIMAG - Grenoble, FR) [dblp]
• Ingo Sander (KTH Royal Institute of Technology, SE) [dblp]
• Klaus Schneider (TU Kaiserslautern, DE) [dblp]
• Alex Shafarenko (University of Hertfordshire, GB) [dblp]
• Chris Shaver (University of California - Berkeley, US) [dblp]
• Wei-Tsun Sun (INRIA - Grenoble, FR) [dblp]
• Reinhard von Hanxleden (Universität Kiel, DE) [dblp]