Abstract
Multi-agent systems are widely used to address large-scale distributed combinatorial applications in the real world. One such application is meeting scheduling (MS), which is defined by a variety of features. The MS problem is naturally distributed and especially subject to many alterations. In addition, this problem is characterized by the presence of users’ preferences that turn it into a search for an optimal rather than a feasible solution. However, in real-world applications users usually have conflicting preferences, which makes the solving process an NP-hard problem. Most research efforts in the literature, adopting agent-based technologies, tackle the MS problem as a static problem. They often share some common properties: allowing the relaxation of any user's time restriction, not dealing with achieving any level of consistency among meetings to enhance the efficiency of the solving process, not tackling the consequences of the dynamic environment, and especially not addressing the real difficulty of distributed systems which is the complexity of message passing operations.
In an attempt to facilitate and streamline the process of scheduling meetings in any organization, the main contribution of this work is a new scalable agent-based approach for any dynamic MS problem (that we called MSRAC, for Meeting Scheduling with Reinforcement of Arc Consistency). In this approach we authorize only the relaxation of users’ preferences while maintaining arc-consistency on the problem. The underlying protocol can efficiently reach the optimal solution (satisfying some predefined optimality criteria) whenever possible, using only minimum localized asynchronous communications. This purpose is achieved with minimal message passing while trying to preserve at most the privacy of involved users. Detailed experimental results on randomly generated MS problems show that MSRAC is scalable and it leads to speed up over other approaches, especially for large problems with strong constraints.