Repairing Timed Automata Clock Guards through Abstraction and Testing

TL;DR

This paper introduces a method to repair faulty clock guards in timed automata by abstracting the automaton into a parametric form, generating test data, and synthesizing constraints to produce a corrected model, validated through experiments.

Contribution

It presents a novel approach combining abstraction, testing, and constraint synthesis to repair clock guards in timed automata, enhancing system correctness.

Findings

Successfully repairs faulty clock guards in timed automata

Uses the IMITATOR tool for parameter constraint synthesis

Demonstrates effectiveness through experimental validation

Abstract

Timed automata (TAs) are a widely used formalism to specify systems having temporal requirements. However, exactly specifying the system may be difficult, as the user may not know the exact clock constraints triggering state transitions. In this work, we assume the user already specified a TA, and (s)he wants to validate it against an oracle that can be queried for acceptance. Under the assumption that the user only wrote wrong guard transitions (i.e., the structure of the TA is correct), the search space for the correct TA can be represented by a Parametric Timed Automaton (PTA), i.e., a TA in which some constants are parametrized. The paper presents a process that i) abstracts the initial (faulty) TA tainit in a PTA pta; ii) generates some test data (i.e., timed traces) from pta; iii) assesses the correct evaluation of the traces with the oracle; iv) uses the IMITATOR tool for synthesizing some constraints phi on the parameters of pta; v) instantiate from phi a TA tarep as final repaired model. Experiments show that the approach is successfully able to partially repair the initial design of the user.