From SOS to Asynchronously Communicating Actors Frank de Boer 1 , Einar Broch Johnsen 2(B ) , Ka I Pun 2,3 , and Silvia Lizeth Tapia Tarifa 2 1 CWI, Amsterdam, The Netherlands f.s.de.boer@cwi.nl 2 Department of Informatics, University of Oslo, Oslo, Norway {einarj,violet,sltarifa}@ifi.uio.no 3 Western Norway University of Applied Sciences, Bergen, Norway Abstract. Structural Operational Semantics (SOS) provides a general format to describe a model as a transition system with very powerful syn- chronization mechanisms. Actor systems are distributed, asynchronously communicating units of computation with encapsulated state, with much weaker means of synchronizing between actors. In this paper, we discuss an implementation of a SOS model using actors in the object-oriented actor language ABS and how to argue that global properties about the model are inherited from the SOS level to the actor implementation. The work stems from a case study modelling the memory system of a cache-coherent multicore architecture. 1 Introduction Structural operational semantics (SOS) [1], introduced by Plotkin in 1981, describes system behavior as transition relations in a syntax-oriented, composi- tional way, using inference rules to capture local transitions and how these com- pose into transitions at the global level. Process synchronization in SOS rules is expressed abstractly using, e.g., assertions over system states and reachability conditions over transition relations as premises, and label synchronization for parallel transitions. This high level abstraction greatly simplifies the verification of system properties. In particular, reasoning about SOS semantics has been used to prove meta-properties for all instances of a model such as type preserva- tion properties for the execution of programs in a programming language (e.g., [2]). In contrast, a direct implementation of an SOS model for the simulation of system behavior is less common, as execution quickly becomes a reachability problem with a lot of backtracking. Often, the implementation of an SOS model can be quite far from the transition rules of the model itself, and, as a result, Supported by SIRIUS: Centre for Scalable Data Access (www.sirius-labs.no) and ADAPt: Exploiting Abstract Data-Access Patterns for Better Data Locality in Parallel Processing (www.mn.uio.no/ifi/english/research/projects/adapt/). c  Springer Nature Switzerland AG 2020 J. Camara and M. Steffen (Eds.): SEFM 2019 Workshops, LNCS 12226, pp. 269–275, 2020. https://doi.org/10.1007/978-3-030-57506-9_20