title: Sparse cliques trump scale-free networks in coordination and competition.
abstract: Cooperative behavior, a natural, pervasive and yet puzzling phenomenon, can be significantly enhanced by networks. Many studies have shown how global network characteristics affect cooperation; however, it is difficult to understand how this occurs based on global factors alone, low-level network building blocks, or motifs are necessary. In this work, we systematically alter the structure of scale-free and clique networks and show, through a stochastic evolutionary game theory model, that cooperation on cliques increases linearly with community motif count. We further show that, for reactive stochastic strategies, network modularity improves cooperation in the anti-coordination Snowdrift game and the Prisoner's Dilemma game but not in the Stag Hunt coordination game. We also confirm the negative effect of the scale-free graph on cooperation when effective payoffs are used. On the flip side, clique graphs are highly cooperative across social environments. Adding cycles to the acyclic scale-free graph increases cooperation when multiple games are considered; however, cycles have the opposite effect on how forgiving agents are when playing the Prisoner's Dilemma game.
authors.affiliation: School of Systems and Enterprises, Stevens Institute of Technology, Hoboken NJ, USA.|Raytheon Space and Airborne Systems, El Segundo CA, USA.
authors.forename: David A
authors.initials: DA
authors.lastname: Gianetto
authors.affiliation: School of Systems and Enterprises, Stevens Institute of Technology, Hoboken NJ, USA.
authors.forename: Babak
authors.initials: B
authors.lastname: Heydari
mesh_terms: D005075:Biological Evolution; D003163:Competitive Behavior; D003299:Cooperative Behavior; D005716:Game Theory; D006801:Humans; D007398:Interpersonal Relations; D008960:Models, Psychological; D000068956:Prisoner Dilemma; D012944:Social Support