Distinguing Non-deterministic Timed Finite State Machines

Conformance testing with the guaranteed fault coverage is based on distinguishing faulty system implementations from the corresponding system specification. We consider timed systems modeled by timed possibly nondeterministic finite state machines (TFSMs) and propose algorithms for distinguishing two TFSMs. In particular, we present a preset algorithm for separating two separable TFSMs and an adaptive algorithm for r-distinguishing two possibly non-separable TFSMs. The proposed techniques extend existing methods for untimed non-deterministic FSMs by dealing with the fact that unlike untimed FSMs in general, a TFSM has an infinite number of timed inputs. Correspondingly we state that the upper bounds on the length of distinguishing sequences are the same as for untimed FSMs.