Search-based Trace Diagnostic

Preprint, 2024

Cyber-physical systems (CPS) development requires verifying whether system behaviors violate their requirements. This analysis
often considers system behaviors expressed by execution traces and requirements expressed by signal-based temporal properties. When an
execution trace violates a requirement, engineers need to solve the trace diagnostic problem: They need to understand the cause of the breach. Automated trace diagnostic techniques aim to support engineers in the trace diagnostic activity. This paper proposes search-based trace-diagnostic (SBTD), a novel trace-diagnostic technique for CPS requirements. Unlike existing techniques, SBTD relies on evolutionary search. SBTD starts from a set
of candidate diagnoses, applies an evolutionary algorithm iteratively to generate new candidate diagnoses (via mutation, recombination,
and selection), and uses a fitness function to determine the qualities of these solutions. Then, a diagnostic generator step is performed to
explain the cause of the trace violation. We implemented Diagnosis, an SBTD tool for signal-based temporal logic requirements expressed
using the Hybrid Logic of Signals (HLS). We evaluated Diagnosis by performing 34 experiments for 17 trace-requirements combinations
leading to a property violation and by assessing the effectiveness of SBTD in producing informative diagnoses and its efficiency in generating
them on a time basis. Our results confirm that Diagnosis can produce informative diagnoses in practical time for most of our experiments (33
out of 34).