There are no universal criteria and foundations to evaluate approximate algorithms in combinatorial optimization fields at present

however

the focusing problems make great difference to the efficiency of algorithms.In this paper

we take the Job-shop problem as an example

analyze the characteristics of the scheduling problem and its solutions space

and propose a concept:cutting-factor.Our research shows that cutting-factor can decide the size of the solution space

and processing time of the operations can influence the roughness of the solution space;cutting-faiter and processing-time's distribution can indicate the complexity of the scheduling problem.Our study is an exploring step towards establishing universal criteria for approximate algorithms

and can guide the design of algorithms to some extent.