Editorial for the Special Issue on Open Problems in Concurrency Theory

The research seminar “Open Problems in Concurrency Theory” (OPCT 2014) was a prolific and successful gathering of the leading researchers in concurrency theory aiming to identify the most important open problems in the area. This special issue contains a selected set of papers of the 44 presentations given during the seminar. The meeting was held on 18–21 June 2014 in the Fresco Room of the University Residential Center of Bertinoro, Italy, and supported by the IFIP Working Group 1.8. The special issue features 8 articles ranging from classical process theory and behavioural abstraction up to coalgebraic semantics, types, and security. In the first paper, “The role of concurrency in an evolutionary view of programming abstractions”, the author examines how concurrency has been embodied in mainstream programming languages and discuss different abstraction levels of present-day concurrent programming languages. The paper “Revisiting sequential composition in process calculi” reviews the various ways sequential composition is defined in traditional process calculi. The author argues that such definitions somehow limit the dissemination of concurrency theory ideas among computer scientists. An alternative approach to sequential composition based on a symmetric binary operator and write-many variables is proposed. A survey of existing approaches based on behavioural types that are aimed at ensuring security and trustworthiness properties in realistic distributed applications is presented in the paper “Combining behavioural types with security analysis”.