Random Generation of Small Quantitative Automata for Algorithm Debugging

Abstract

Analysis algorithms for quantitative automata are complex and hard to validate. Existing approaches -- benchmarks, mutation testing, uniform random generation -- each fail to expose subtle implementation bugs. We present a framework that repeatedly 1) generates random quantitative automata that are non-degenerate by construction, 2) tests each against a target property, and 3) shrinks any violation to a local minimum, yielding a small, actionable counterexample. We implement the framework for parametric timed automata (PTA) and apply it to IMITATOR, a mature model checker for PTA, uncovering 5 previously unknown bugs, one of which was exposed by a counterexample with just 2 locations and 1 transition.