Preplay Communication Does Not Solve Prisoner’s Dilemma

It is challenging to reach a balance between desired cooperation among agents as the team tasks require and intrinsic, logical self-interest of each agent. A powerful tool in understanding the evolution of cooperation is game theory, especially the game setup prisoner’s dilemma (PD) in which defection is a strictly dominating strategy against cooperation, and thus natural to be employed to mimic agents’ instinct. It is a long-standing conjecture that cooperation can survive in evolutionary PD games by the use of preplay communication that allows each player to send a message to her opponent before they play and consequently makes it possible to act based on the messages she receives. However, we prove that this conjecture, under a simple but standard preplay communication mechanism, is surprisingly fals