The variations of harmony search and its current research trends

Since the HS was firstly assessed and utilized in the optimal cost design of water distribution network in 2006, it has attracted growing research interest in handling a large variety of optimization problems. As aforementioned, the original HS has its own inherent drawbacks (slow convergence and outdated information). Hence, a lot of relevant literature proposes many variations of the HS, which can be classified into two major categories: modification based on the regular HS and hybridization with other NIC algorithms. The former targets the improvement of parameters or operators of the HS to enhance the quality of solutions, while the latter incorporates some optimization approaches to overcome its drawbacks and improve the performance. From the viewpoint of structure, the cooperation in the fusion strategies of the hybrid HS methods could be in the manner of either cooperator or embedded operators. This chapter first gives an overview of the variations of the HS and the current research trends, and a modified HS method for constrained optimization is next discussed in details.