Need, Greed and Noise: Competing Strategies in a Trading Model
  We study an economic model where agents trade a variety of products by using one of three competing rules: "need", "greed" and "noise". We find that the optimal strategy for any agent depends on both product composition in the overall market and composition of strategies in the market. In particular, a strategy that does best on pairwise competition may easily do much worse when all are present, leading, in some cases, to a "paper, stone, scissors" circular hierarchy. 
R. Donangelo, A. Hansen, K. Sneppen, S.R. Souza