Diffusion in geographical space is an expression of a large variety of logics in interactions : space logics, social logics and economic logics. Those coexist and are exerted starting from individuals who interact in a repetitive way. Multi-agents simulation allows the modeling of these dynamic processes and then makes it possible to investigate in a deductive way the consequences of our theories and to test the validity of our assumptions. The interest of such an approach for the explanation in geography is argued from a theoretical point of view, by the talk of the theoretical corpus of these new methods and their transfer in social sciences, and from an empirical point of view, by the study of the diffusion of the grazing-improvement sub...