  Distributed multi-writer atomic registers are at the heart of a large number
of distributed algorithms. While enjoying the benefits of atomicity,
researchers further explore fast implementations of atomic reigsters which are
optimal in terms of data access latency. Though it is proved that multi-writer
atomic register implementations are impossible when both read and write are
required to be fast, it is still open whether implementations are impossible
when only write or read is required to be fast. This work proves the
impossibility of fast write implementations based on a series of chain
arguments among indistiguishable executions. We also show the necessary and
sufficient condition for fast read implementations by extending the results in
the single-writer case. This work concludes a series of studies on fast
implementations of distributed atomic registers.
