This paper introduces an improved evolutionary algorithm based on the Imperialist Competitive Algorithm (ICA), called Quad Countries Algorithm (QCA). The Imperialist Competitive Algorithm is inspired by socio-political process of imperialistic competition in the real world and has shown its reliable performance in optimization problems. In the ICA, the countries are classified into two groups: Imperialists and Colonies. However, in the QCA, two other kinds of countries including Independent and Seeking Independence are added to the countries collection. In the ICA also the Imperialists’ positions are fixed, while in the QCA Imperialists may move. The proposed algorithm was tested by well-known benchmarks, and the compared results of the QCA with results of ICA, GA [12], PSO [12], PS-EA [12] and ABC [11] show that the QCA has better performance than all mentioned algorithms. Among them, the QCA,
M. A. Soltani-Sarvestani, Shahriar Lotfi, Fatemeh