Abstract
In this paper cluster validity measures are investigated and compared. The studied measures are the sum of the traces of the fuzzy covariances within clusters, Xie-Beni's index, Davies-Bouldin's index, and Fukuyama-Sugeno's measure. These measures are kernelized and applied to the determination of the number of clusters having nonlinear boundaries generated by kernel-based clustering algorithms. We also propose a clustering algorithm using Fukuyama-Sugeno's measure.