Hierarchical cluster ensemble model based on knowledge granulation

Cluster ensemble has been shown to be very effective in unsupervised classification learning by generating a large pool of different clustering solutions and then combining them into a final decision. However, the task of it becomes more difficult due to the inherent complexities among base cluster results, such as uncertainty, vagueness and overlapping. Granular computing is one of the fastest growing information-processing paradigms in the domain of computational intelligence and human-centric systems. As the core part of granular computing, the rough set theory dealing with inexact, uncertain, or vague information, has been widely applied in machine learning and knowledge discovery related areas in recent years. From these perspectives, in this paper, a hierarchical cluster ensemble model based on knowledge granulation is proposed with the attempt to provide a new way to deal with the cluster ensemble problem together with ensemble learning application of the knowledge granulation. A novel rough distance is introduced to measure the dissimilarity between base partitions and the notion of knowledge granulation is improved to measure the agglomeration degree of a given granule. Furthermore, a novel objective function for cluster ensembles is defined and the corresponding inferences are made. A hierarchical cluster ensemble algorithm based on knowledge granulation is designed. Experimental results on real-world data sets demonstrate the effectiveness for better cluster ensemble of the proposed method.