Davide Basile

Team automata were introduced as a flexible extension of I/O automata to model collaborative behaviour in component-based and distributed systems. Their distinctive features include multi-party communication and a liberal synchronisation mechanism: components may jointly execute shared actions according to synchronisation policies that specify which subsets of components participate as senders or receivers. While this makes team automata well suited for modelling coordination, existing communication is synchronous and therefore insufficient for capturing certain behavioural aspects (e.g., due to message reordering) of modern networks and distributed systems, in which communication is typically asynchronous and message delays are unpredictable. In this paper, we introduce asynchronous team automata (ATeams), which extend team automata with buffers to model asynchronous communication, in addition to conventional synchronous interaction. ATeams support individual interactions involving multiple senders and receivers, unlike well-known asynchronous models such as communicating finite-state machines and multi-party session types. We formalise the syntax and operational semantics of ATeams, study well-formedness and well-behavedness conditions, and present the prototypical tool that supports specification, animation and automated checks. This proposes ATeams as a unifying semantic foundation for modelling and analysis of heterogeneous synchronous–asynchronous multi-party interactions.

Mutation Testing (MT) is a technique employed to assess the efficacy of tests by introducing artificial faults, known as mutations, into the system. The goal is to evaluate how well the tests can detect these mutations. These artificial faults are generated using mutation operators, which produce a set of mutations derived from the original system. Mutation operators and frameworks exist for a variety of programming languages, and model-based mutation testing is gaining traction, particularly for timed safety-critical systems. This paper focuses on extending MT to Networks of Timed Automata (NTAs), an area that has not been extensively explored. We introduce mutation operators designed for NTAs specified in UPPAAL, aiming to create temporal interaction faults. We assess the effectiveness of these operators on five UPPAAL NTAs sourced from the literature, specifically examining the generation of equivalent and duplicate mutants. Our results demonstrate a varied prevalence of equivalent mutants (from 12% to 71%) while the number of duplicates is less. In all cases, timed bisimulation was able to process each mutant pair in less than one second.