A theoretical investigation of generalized voters for redundant systems

The authors generalize several commonly used voting techniques to arbitrary N-version systems with arbitrary output types using a metric space framework. In particular, they introduce the generalized median voter, which extends the thresholdless midvalue selection technique to arbitrary metric spaces and obviates most of the problems associated with inexact voting. They also introduce the formalized majority voter, which allows an inexact notion of equality between version outputs using a threshold. The authors then show that the median output determined by the generalized median voter will always be contained in the set of consensus outputs produced by the formalized majority voter. In addition, the authors introduce the formalized plurality voter which generalizes two-out-of-N type voters and the weighted averaging voter which generalizes dynamic voting. The performance of these voters under different postulated failure scenarios is compared.<>