关键词: Backbone, 极值过程, 自组织临界模型, 旅行商问题

Abstract: Because of the inconsistence between optimal fitness of variables and optimal objective，local searching algorithm using extremal process rules is ineffective for Traveling Salesman Problem（TSP）.We change the definition of variables and make them related with the objective function，which enhances the searching capability of an individual solution.Through comparison of objectives with different parameter values of τ，we found that there is the optimal value of τ to get the best searching performance.This result provides rules for parameter setting and it is independent of mutation ways of variables.However，when an individual solution gets near to sub-optima，the improvement of objective function is very slow and the solution cannot arrive at the optimum quickly.So we introduce the concept of backbone of combinatorial optimization solutions.While the colony comes into the optimal space engine，we fix the same parts in the solutions to reserve the best solution，and reduce the scale of real problem to solve to continue the optimization，which enhances the searching capability，and improve the searching performance.

Key words: Backbone, extremal process, self-organized criticality model, Traveling Salesman Problem（TSP）