A New Agglomerative 2-3 Hierarchical Clustering Algorithm

We studied a new general clustering procedure, that we call here Agglomerative 2-3 Hierarchical Clustering (2-3 AHC), which was proposed in Bertrand (2002a, 2002b). The three main contribution of this paper are: first, the theoretical study has led to reduce the complexity of the algorithm from O(n^3) to O(n^2 log n). Secondly, we proposed a new 2-3 AHC algorithm that simplifies the one proposed in 2002 (its principle is closer to the principle of the classical AHC). Finally, we proposed a first implementation of a 2-3 AHC algorithm.ou