  We show the equivalence of two distributed computing models, namely
reconfigurable broadcast networks (RBN) and asynchronous shared-memory systems
(ASMS), that were introduced independently. Both RBN and ASMS are systems in
which a collection of anonymous, finite-state processes run the same protocol.
In RBN, the processes communicate by selective broadcast: a process can
broadcast a message which is received by all of its neighbors, and the set of
neighbors of a process can change arbitrarily over time. In ASMS, the processes
communicate by shared memory: a process can either write to or read from a
shared register. Our main result is that RBN and ASMS can simulate each other,
i.e. they are equivalent with respect to parameterized reachability, where we
are given two (possibly infinite) sets of configurations C and C' defined by
upper and lower bounds on the number of processes in each state and we would
like to decide if some configuration in C can reach some configuration in C'.
Using this simulation equivalence, we transfer results of RBN to ASMS and vice
versa. Finally, we show that RBN and ASMS can simulate a third distributed
model called immediate observation (IO) nets. Moreover, for a slightly stronger
notion of simulation (which is satisfied by all the simulations given in this
paper), we show that IO nets cannot simulate RBN.
