no code implementations • 2 Dec 2019 • Anup Bhattacharya, Jan Eube, Heiko Röglin, Melanie Schmidt
We show that this is not the case by presenting a family of instances on which greedy k-means++ yields only an $\Omega(\ell\cdot \log k)$-approximation in expectation where $\ell$ is the number of possible centers that are sampled in each iteration.
no code implementations • 11 Jul 2019 • Anna Großwendt, Heiko Röglin, Melanie Schmidt
In this paper, we show that Ward's method computes a $2$-approximation with respect to the $k$-means objective function if the optimal $k$-clustering is well separated.