Title: Adaptive Load Balancing: a study in co-learning Authors: Andrea Schaerf, Yoav Shoham and Moshe Tennenholtz aschaerf@dis.uniroma1.it, shoham@flamingo.stanford.edu, moshet@ie.technion.ac.il Abstract: This is a short abstract submitted to the Adaptation and Learning in Multiagent Systems workshop. A much longer and detailed version of this paper, called "Adaptive Load Balancing: A Study in Multi-Agent Learning", will appear in the Journal of Artificial Intelligence Research. In our work we study the process of multi-agent reinforcement learning in the context of load balancing in a distributed system without use of either central coordination or explicit communication. We first define a precise framework in which to study adaptive load balancing, improtan features of which are its stochastic nature and the purely local inforamtion available to individual agents. Given this framework, we show illuminating results on the interplay between basic adaptive beehavior parameters and their effect on system efficiency. We then investigate the properties of adaptive load balancing in heterogeneous populations, and expose various phenomena related to the issue of exploration vs. exploitation in that context. In addition, we show that naive use of communication may not improve, and might even deteriorate system efficiency.