Sequential construction of a circular consecutive-2 system

Derman, Lieberman and Ross solved the problem of sequentially assigning n components with different reliabilities to a consecutive-2 linear system to maximize the system reliability. Furthermore, they show that the optimal assignment is invariant, i.e., it depends only on the ranking of the component reliabilities, but not their values. We study the same problem for the consecutive-2 circular system and prove that an invariant optimal assignment does not exist. But we reduce the number of candidates of an optimal assignment from n! to bn/2c − 2. We also find the first-order invariant optimal assignment.  2000 Elsevier Science B.V. All rights reserved.