  We define a hierarchical clustering method: $\alpha$-unchaining single
linkage or $SL(\alpha)$. The input of this algorithm is a finite metric space
and a certain parameter $\alpha$. This method is sensitive to the density of
the distribution and offers some solution to the so called chaining effect. We
also define a modified version, $SL^*(\alpha)$, to treat the chaining through
points or small blocks. We study the theoretical properties of these methods
and offer some theoretical background for the treatment of chaining effects.
