An Equivariance Theorem with Applications to Renaming (Preliminary   Version)
  In the renaming problem, each process in a distributed system is issued a unique name from a large name space, and the processes must coordinate with one another to choose unique names from a much smaller name space. We show that lower bounds on the solvability of renaming in an asynchronous distributed system can be formulated as a purely topological question about the existence of an equivariant chain map from a topological disk to a topological annulus. Proving the non-existence of such a map implies the non-existence of a distributed renaming algorithm in several related models of computation. 
Armando Casta\~neda, Maurice Herlihy and Sergio Rajsbaum
cs.DC