This paper deals with a method for designing a digital system which will remain operational in spite of the failure of some of its components. A scheme and its realization are presented for automatically reconfiguring a 5MR (five modular redundancy system or 5-input majority voting system) into a triple modular redundancy (TMR) system under a single or double module failures. The scheme can tolerate a double fault followed by a single fault which can neither be tolerated by a 5MR nor by a hybrid redundancy system with a TMR core. It uses no spare units and the circuit realization is relatively simple. The modular structure of the logic design for the proposed scheme should make the testing of the system easier. The scheme can be used in both binary and multivalued systems.

These comments point out first that the difficulties encountered in a recent paper1in applying the theorems of Boolean algebra to a multivalued system using max and min functions are not due to the type of complement that is chosen, but due to the attempt to deqne a multivalued Boolean algebra using the max and min functions which are not Boolean functions except in the 2-valued case; and second, that the three types of complement defined are well known in the context of multivalued non-Boolean algebras.