Crowd-anticrowd theory of the Minority Game
  The Minority Game is a simple yet highly non-trivial agent-based model for a complex adaptive system. Despite its importance, a quantitative explanation of the game's fluctuations which applies over the entire parameter range of interest has so far been lacking. We provide such a quantitative description based on the interplay between crowds of like-minded agents and their anti-correlated partners (anticrowds). 
M. Hart, P. Jefferies, N.F. Johnson (Oxford U.), P.M. Hui (CUHK)