Fault-Tolerant Asynchronous Networks

The design of fault-tolerant asynchronous networks has been an unsolved problem. In this paper, necessary and sufficient conditions on state assignments for fault-tolerant asynchronous networks are given. Three design techniques, based on Liu's 2
^so
- 1 assignment, Friedman et al.'s (2, 2) separating system, and (2s
_o
+ 1) assignments, are given for fault-tolerant asynchronous networks. The earlier Liu's upper bound on state variables for USTI assignment for 2
^so
rows is improved to 2
^so
- 2
^so
-3
.