Effective Elections for Anonymous Mobile Agents
We present distributed protocols for electing a leader among k mobile agents that are dispersed among the n nodes of a graph. While previous solutions for the agent election problem were restricted to specific topologies or under specific conditions, the protocols presented in this paper face the problem in the most general case, i.e. for an arbitrary topology where the nodes of the graph may not be distinctly labelled and the agents might be all identical (and thus indistinguishable from each other). In such cases, the agent election problem is often difficult, and sometimes impossible to solve using deterministic means. We have designed protocols for solving the problem that—unlike previous solutions—are effective, meaning that they always succeed in electing a leader under any given setting if at all it is possible, and otherwise detect the fact that election is impossible in that setting. We present several election protocols, all effective. Starting with the straightforward solution, that requires an exponential amount of edge-traversals by the agents, we describe significantly more efficient algorithms; in the latter the total number of edge-traversals made by the agents is always polynomial, their difference is in the amount of bits of storage they required at the nodes.
KeywordsMobile Agent Leader Election Span Forest Agent Move Election Algorithm
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- 2.Angluin, D.: Local and global properties in networks of processors. In: Proc. 12th ACM Symp. on Theory of Computing (STOC 1980), pp. 82–93 (1980)Google Scholar
- 4.Barrière, L., Flocchini, P., Fraigniaud, P., Santoro, N.: Can we elect if we cannot compare? In: Proc. 15th ACM Symp. on Parallel Algorithms and Architectures (SPAA 2003), pp. 200–209 (2003)Google Scholar
- 5.Barrière, L., Flocchini, P., Fraigniaud, P., Santoro, N.: Election and rendezvous in fully anonymous networks with sense of direction. In: Theory of Computing Systems (to appear, 2006). Preliminary version in Proc. 10th Coll. on Structural Information and Communication Complexity (SIROCCO 2003), pp. 17–32 (2003) Google Scholar
- 7.Bender, M., Fernandez, A., Ron, D., Sahai, A., Vadhan, S.: The power of a pebble: Exploring and mapping directed graphs. In: Proc. 30th ACM Symp. on Theory of Computing (STOC 1998), pp. 269–287 (1998)Google Scholar
- 8.Boldi, P., Shammah, S., Vigna, S., Codenotti, B., Gemmell, P., Simon, J.: Symmetry breaking in anonymous networks: Characterizations. In: Proc. 4th Israel Symp. on Theory of Computing and Systems, pp. 16–26 (1996)Google Scholar
- 13.Kranakis, E.: Symmetry and computability in anonymous networks: A brief survey. In: Proc. 3rd Int. Conf. on Structural Information and Communication Complexity (SIROCCO 1997), pp. 1–16 (1997)Google Scholar
- 16.Sakamoto, N.: Comparison of initial conditions for distributed algorithms on anonymous networks. In: Proc. 18th ACM Symposium on Principles of Distributed Computing (PODC 1999), pp. 173–179 (1999)Google Scholar