Local tag structures have become frequent through Web 2.0: Users "tag" their data without specifying the underlying semantics. Every user annotates items in an individual way using the own labels. Even if two users happen to use a tag with the same name, it need not mean the same. Moreover, within the collection of a single user, media items are tagged multiply using different aspects, e.g., topic, genre, occasion, mood. Again, several users applying the same name for an aspect does not imply that actually the same aspect is meant. Nevertheless, users could benefit from the tagging work of others (folksonomies). The set of items clustered together by the same label in one user’s collection form a pattern. Knowing this pattern is informative for another user. In contrast to other cluster ensemble methods or distributed clustering, a global model (consensus) is not the aim. Each user wants to keep the tags already annotated, wants to keep the diverse aspects under which the...