Extremal Optimization (EO) is an optimization heuristic inspired by the Bak-Sneppen model of self-organized criticality from the field of statistical physics. This heuristic was designed initially to address combinatorial optimization problems such as the travelling salesman problem and spin glasses, although the technique has been demonstrated to function in optimization domains.
Read more about Extremal Optimization: Relation To Self-organized Criticality, Relation To Computational Complexity, The Technique, Variations On The Theme and Applications