Basic Sequential Algorithmic Scheme - BSASIn this algortihm each data vector is considered only once and the number of cluster in not known a priori. However, the maximum number of clusters, q, is decided beforehand. Let d(x, C) denote the distance between data vector x and a cluster C. Furthermore, q is the allowed threshold of dissimilarity.
Modified Basic Sequential Algorithmic Scheme - MBSASMBSAS algorithm consists of two phases. The clusters are determined in the first phase via assignment of some of the vectors of X to them. The unassigned vectors are assigned to the appropriate clusters in the second phase.