Efficiency and stability on multi-level structures

Multi-level structures are extremely popular in many organizations and social institutions. By game theory, this paper shows that two-level structures are more efficient than three-level structures, while with evolutionary graph technique we find that three-level structures are more stable than two-level ones. The results are correspondingly extended to more general situations. In summary, the multi-level structures with different numbers of levels are compared in this work. Furthermore, evolutionary graph theory is extended to social field in this paper.