Phase 2: Retrieving the individual clusters.

After having identified the $2^{N_t-1}$ groups of symmetric clusters, the two individual threads for each group need to be retrieved. Since only two clusters have to be retrieved in each group in this phase, the inter-cluster distances will be much larger than the distances between neighboring points of the same cluster and therefore performing spectral clustering using conventional Euclidian distances on each group is sufficient to obtain the $2^{N_t}$ final symbol clusters.