Adjudicators for Diverse-Redundant Components

In fault-tolerant components reaIized using replication, severai alternate results are produce d, from which a single correct result must be derived. This is done by a mechanism, that we call an adjudicator Ca concept more generaI than a voter), which uses as its inputs the individuaI results produced by the replicated subcomponents comprising the redundant component. This paper gives a rigourous definition of the adjudication problem, summarizes the existing literature on the topic, and investigates the use ofprobabilistic knowIedge about errors/faults in the subcomponents of a fault tolerant component to obtain good adjudication functions. The concept of an optimal adjudicator is introduced and discussed. Release number Release status A vailability status A vailable from 1 Final Public Felicita Di Giandomenico, lEI-CNR, Via S. Maria 46,56126 Pisa, ItaIy. A shorter version of this report has been accepted for presentation at the Ninth Symposium on Reliable Distributed Systems, Huntsville, Alabama, October 9-11, 1990.