AGGREGATION METHODS FOR RELIABILITY AND AVAILABILITY CALCULATIONS

Aggregation is a way to reduce the size of Markovian reliability and a vailability problems. Since exact aggregation is only possible in exce ptional cases, we introduce a canonical partition for the Markovian st ates for systems with 2-state components that allows a systematic stud y of approximate aggregation. Restriction and prolongation operators a re introduced to define aggregation. Four methods are proposed to defi ne approximate systems of birth and death type. Examples are given for k-out-of-4 systems and for a 7 component system.