Structural operational semantics (SOS) is one of the most common formalisms for specifying language semantics. There has been much interest in automatically deriving small-step SOS definitions from big-step definitions and vice versa, as well as towards extrapolating language implementations from these inductive, declarative definitions. This work presents Computation-Tree Semantics (CTS) in which semantic configurations are tree-structured, unlike standard SOS-configurations which are “flat”. This tree-structure is key in making our approach algorithmic, meaning it is able to describe how a transition is produced, contrary to the traditional declarative approach taken by SOS. We show how one can -- in a straight-forward manner -- obtain a CTS from the big-step semantics of a simple arithmetic language, a simple while language, and the call-by-need lambda-calculus as given by Launchbury. From the resulting CTS, we then obtain a small-step understanding of all these languages. The arithmetic language example is formalised in Coq/Rocq.

While System of Systems (SoS) architectures for large and complex software projects are gaining momentum, the commonly used modeling and tooling approaches are still general-purpose or oriented towards single systems. Developers could benefit from methods and tools that avoid system-centric details in favor of native SoS modeling support. This paper presents a diagram-centric modeling tool with native SoS modeling support. The tool is implemented as a plugin for the Eclipse Papyrus modeling tool. The tool was showcased as a demo at MODELS'22. The code of the plugin is freely available via Github.