A knowledge-based analysis of global function computation

作者：Halpern Joseph Y^*; Petride Sabina

来源：Distributed Computing, 2010, 23(3): 197-224.

DOI：10.1007/s00446-010-0111-7

Consider a distributed system N in which each agent has an input value and each communication link has a weight. Given a global function, that is, a function f whose value depends on the whole network, the goal is for every agent to eventually compute the value f (N). We call this problem global function computation. Various solutions for instances of this problem, such as Boolean function computation, leader election, (minimum) spanning tree construction, and network determination, have been proposed, each under particular assumptions about what processors know about the system and how this knowledge can be acquired. We give a necessary and sufficient condition for the problem to be solvable that generalizes a number of well-known results (Attyia et al. in J ACM 35(4):845-875, 1988; Yamashita and Kameda in IEEE Trans Parallel Distrib Syst 7(1):69-89, 1996; Yamashita and Kameda in IEEE Trans Parallel Distrib Syst 10(9):878-887, 1999). We then provide a knowledge-based (kb) program (like those of Fagin et al. (Reasoning about knowledge, MIT Press, Cambridge, 1995, Distrib Comput 10(4):199-225, 1997)) that solves global function computation whenever possible. Finally, we improve the message overhead inherent in our initial kb program by giving a counterfactual belief-based program (Halpern and Moses in Distrib Comput 17(2):91-106, 2004) that also solves the global function computation whenever possible, but where agents send messages only when they believe it is necessary to do so. The latter program is shown to be implemented by a number of well-known algorithms for solving leader election.

• 出版日期2010-11