Detecting observability problems in distributed testing

Application of a test or checking sequence in a distributed test architecture often requires the use of external coordination message exchanges among multiple remote testers for eluding potential controllability and observability problems. Recent literature reports on conditions on a given finite state machine (FSM) under which controllability and observability problems can be overcome without using external coordination messages. However, these conditions do not guarantee that any test/checking sequence constructed from such FSMs are free from controllability and observability problems. For a given test or checking sequence, this paper investigates whether it is possible to eliminate the need for external coordination messages and proposes algorithms to identify or construct subsequences either within the given sequence or as an extension to the given sequence, respectively.