“…Our visualization analysis on five datasets reveals that there are extremely complex cluster structures, i.e., the datasets contain a large number of classes, unbalanced cluster membership, low intracluster dissimilarity, high intercluster similarity, high dimensionality, and arbitrary cluster shapes, which results in failures for existing clustering algorithms including ours. Moreover, our empirical studies along with others [21], [32], [33], [37]- [40] indicate that our RPCL network ensemble on four representations described in Section II performs well for only the data with balanced and a small number of clusters structures, which is caused by the limitation of the coarse representations and RPCL network.…”