Brief Announcement: Readers of Wait-Free Unbounded Registers Must Write

Implementing stronger read/write registers from weaker ones is a classical problem in the theory of distributed computing. In some such implementations, implemented read operations have the desirable property of not having to write to the base registers used in the implementation. In other cases, it has been proved that implementations cannot have this property. Here, we describe a novel result of the latter type. Although a lock-free implementation of an unbounded register can be built where reads do not write, we show that in any wait-free implementation of unbounded registers from bounded registers, the implemented read operations must write to shared memory.