Yu You-Yang, Xu Chen, Gu Guo-Qing, Hui Pak Ming
School of Information Science and Technology, East China Normal University, Shanghai 200062, China.
Phys Rev E Stat Nonlin Soft Matter Phys. 2008 Jan;77(1 Pt 1):011106. doi: 10.1103/PhysRevE.77.011106. Epub 2008 Jan 8.
We study the effects of the existence of another type of agents, called spies, in the minority game (MG). Unlike the normal agents in the MG, the spies do not carry any strategy. Instead, they decide their action by scouting some normal agents and take the minority action of the spied group. For a few spies and when there is useful information in the normal agents' actions, the spies can avoid the crowd effect of the normal agents and win more readily. When information becomes less useful and when more spies are present, the spies' crowd effect hurts the success rate of the spies themselves, and the normal agents could have a higher success rate than the spies. More spies actually assist more normal agents to win, as the spies also provide more winning quotas. This leads to a nonmonotonic behavior in the total success rate of the population as a function of the fraction of spies.
