Does mobility decrease cooperation?
  We explore the minimal conditions for sustainable cooperation on a spatially distributed population of memoryless, unconditional strategies (cooperators and defectors) in presence of unbiased, non contingent mobility in the context of the Prisoner's Dilemma game. We find that cooperative behavior is not only possible but may even be enhanced by such an ``always-move'' rule, when compared with the strongly viscous (``never-move'') case. In addition, mobility also increases the capability of cooperation to emerge and invade a population of defectors, what may have a fundamental role in the problem of the onset of cooperation. 
Mendeli H. Vainstein, Ana Tereza Costa Silva and Jeferson J. Arenzon