Reaching and Distinguishing States of Distributed Systems

Some systems interact with their environment at physically distributed interfaces, called ports, and in testing such a system it is normal to place a tester at each port. Each tester observes only the events at its port and it is known that this limited observational power introduces additional controllability and observability problems into testing. Given a multi-port finite state machine (FSM) M, we consider the problems of defining strategies for the testers to either reach a given state of M or to distinguish two states of M. These are important problems since most techniques for testing from a single-port FSM use sequences that reach and distinguish states. Both problems can be solved in low-order polynomial time for single-port FSMs but we prove that the corresponding decision problems are undecidable for multi-port FSMs. However, we also show that they can be solved in low order polynomial times for deterministic FSMs if we restrict attention to controllable tests. These resul...

• Type: Journal
• Year: 2010
• Where: SIAMCOMP
• Authors: Robert M. Hierons
• Keywords: Multi-port Fsms, Problems, SIAMCOMP 2010, Single-port Fsms