title: Threshold Games and Cooperation on Multiplayer Graphs.
abstract: OBJECTIVE
  The study investigates the effect on cooperation in multiplayer games, when the population from which all individuals are drawn is structured-i.e. when a given individual is only competing with a small subset of the entire population.
  
  
  METHODS
  To optimize the focus on multiplayer effects, a class of games were chosen for which the payoff depends nonlinearly on the number of cooperators-this ensures that the game cannot be represented as a sum of pair-wise interactions, and increases the likelihood of observing behaviour different from that seen in two-player games. The chosen class of games are named "threshold games", and are defined by a threshold, M > 0, which describes the minimal number of cooperators in a given match required for all the participants to receive a benefit. The model was studied primarily through numerical simulations of large populations of individuals, each with interaction neighbourhoods described by various classes of networks.
  
  
  RESULTS
  When comparing the level of cooperation in a structured population to the mean-field model, we find that most types of structure lead to a decrease in cooperation. This is both interesting and novel, simply due to the generality and breadth of relevance of the model-it is likely that any model with similar payoff structure exhibits related behaviour. More importantly, we find that the details of the behaviour depends to a large extent on the size of the immediate neighbourhoods of the individuals, as dictated by the network structure. In effect, the players behave as if they are part of a much smaller, fully mixed, population, which we suggest an expression for.
authors: Interacting Minds Center, Aarhus University, DK-8000 Aarhus C, Denmark.|Department of Engineering, Aarhus University, DK-8000 Aarhus C, Denmark.
authors: Kaare B
authors: KB
authors: Mikkelsen
authors: Interacting Minds Center, Aarhus University, DK-8000 Aarhus C, Denmark, 2. Interdisciplinary Center for Organizational Architecture(ICOA), Aarhus University, DK-8210 Aarhus V, Denmark.|Interdisciplinary Center for Organizational Architecture (ICOA), Aarhus University, DK-8210 Aarhus V, Denmark.
authors: Lars A
authors: LA
authors: Bach
mesh_terms: D000465:Algorithms; D005716:Game Theory; D006801:Humans; D008962:Models, Theoretical