We report a simple method to accurately determine the threshold and the exponent ν of the Bak–Sneppen (BS) model and also investigate the BS universality class. For the random-neighbor version of the BS model, we find the threshold x∗=0.33332(3), in agreement with the exact result x∗=13...

Extremal dynamics is the mechanism that drives the Bak-Sneppen model into a (self-organized) critical state, marked by a singular stationary probability density p(x). With the aim of understanding this phenomenon, we study the BS model and several variants via mean-field theory and simulation....