Complex Observations

Abstract

An uncertain observation of a DES can be ambiguous in the logical content of observed events, in their temporal relationships, and in their source components. However the precedence relationships involving each observed event of an uncertain observation are assumed to be independent of its sender component. When this assumption does not hold, the observation cannot be defined as uncertain any more. Thus the notion of an uncertain observation is further generalized to that of a complex observation and then exploited by a diagnostic approach pertinent to active systems, which is similar to that proposed when the diagnostic problem features an uncertain observation. In fact, the diagnostic approach processes the given complex observation in order to express by means of a concise deterministic graph, called an observation index space, all the sequences of (both logically and source certain) observable events that are consistent with the given observation, where each of them is called an observation instance. Then, the index space of the observation instead of the observation itself is exploited during history reconstruction.