Armando Castañeda

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In the <i>renaming</i> task, <i>n</i>+1 processes start with unique input names from a large space and must choose unique output names taken from a smaller name space, 0,1,&#8230;, <i>K</i>. To rule out trivial solutions, a protocol must be <i>anonymous</i>: the value chosen by a process can depend on its input name and on the execution, but not on the(More)
In the renaming task n+1 processes start with unique input names from a large space and must choose unique output names taken from a smaller name space, namely 0,1,...,K. To rule out trivial solutions, a protocol must be anonymous: the value chosen by a process can depend on its input name and on the execution, but not on the specific process id. Attiya et(More)
In the k-set agreement task each process proposes a value, and it is required that each correct process has to decide a value which was proposed and at most k distinct values must be decided. Using topological arguments it has been proved that k-set agreement is unsolvable in the asynchronous wait-free read/write shared memory model, when k < n, the number(More)
A protocol <i>P</i> is <i>Pareto-optimal</i> if no protocol <i>Q</i> can decide as fast as <i>P</i> for all adversaries, while allowing at least one process to decide strictly earlier, in at least one instance. Pareto optimal protocols cannot be improved upon. We present the first Pareto-optimal solutions to consensus and <i>k</i>-set consensus for(More)
Tasks and objects are two predominant ways of specifying distributed problems. A task specifies for each set of processes (which may run concurrently) the valid outputs of the processes. An object specifies the outputs the object may produce when it is accessed sequentially. Each one requires its own implementation notion, to tell when an execution(More)
In the renaming problem, each process in a distributed system is issued a unique name from a large namespace, 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 can be formulated as a purely topological question about the existence of an(More)
This paper is on the relative power and the relations linking two important synchronization problems in n-process wait-free shared memory models, namely, set agreement and renaming, which are two of the most studied subconsensus tasks. Since the 2006 seminal paper of Gafni, Rajsbaum and Herlihy, it is known that some renaming instances are strictly weaker(More)