Title
Directed soft arc consistency in pseudo trees
Abstract
We propose an efficient method that applies directed soft arc consistency to a Distributed Constraint Optimization Problem (DCOP) which is a fundamental framework of multi-agent systems. With DCOPs a multi-agent system is represented as a set of variables and a set of constraints/cost functions. We focus on DCOP solvers that employ pseudo-trees. A pseudo-tree is a graph structure for a constraint network that represents a partial ordering of variables. Most pseudo-tree-based search algorithms perform optimistic searches using explicit/implicit backtracking in parallel. However, for cost functions taking a wide range of cost values, such exact algorithms require many search iterations, even if the constraint density is relatively low. Therefore additional improvements are necessary to reduce the search process. A previous study used a dynamic programming-based preprocessing technique that estimates the lower bound values of costs. However, there are opportunities for further improvements of efficiency. In addition, modifications of the search algorithm are necessary to use the estimated lower bounds. The proposed method applies soft arc consistency (soft AC) enforcement to DCOP. In the proposed method, directed soft AC is performed based on a pseudo-tree in a bottom up manner. Using the directed soft AC, the global lower bound value of cost functions is passed up to the root node of the pseudo-tree. The value of each cost function is also reduced. As a result, the original problem is converted to an equivalent problem which is efficiently solved using common search algorithms. The performance of the proposed method is evaluated by experimentation. The results show that it is more efficient than previous methods that estimate the lower bound of costs. Moreover, the proposed method is efficient for approximation algorithms that use bounded errors.
Year
DOI
Venue
2009
10.5555/1558109.1558161
AAMAS (2)
Keywords
Field
DocType
soft ac,pseudo tree,multi-agent system,optimistic search,previous method,efficient method,common search algorithm,soft arc consistency,cost function,cost value,arc consistency,multi agent system,multi agent systems,partial order,search algorithm,bottom up,lower bound
Approximation algorithm,Dynamic programming,Local consistency,Mathematical optimization,Search algorithm,Upper and lower bounds,Computer science,Algorithm,Multi-agent system,Backtracking,Bounded function
Conference
Citations 
PageRank 
References 
9
0.64
14
Authors
5
Name
Order
Citations
PageRank
Toshihiro Matsui138062.51
Marius C. Silaghi237547.09
Katsutoshi Hirayama347244.79
Makoto Yokoo43632421.99
Hirohsi Matsuo5131.42