In comparison to the aforementioned feedback mechanisms, ours is arguably much simpler: we only require that the user select a dimension by examining a small number of features for each dimension, as opposed to having the user generate the feature space in an interactive manner or identify clusters that need to be merged or split.
identifying clusters for merging or splitting in Balcan and Blum's algorithm may not be as easy as it appears: for each MERGE or SPLIT decision the user makes, she has to sample a large number of documents from the cluster(s), read through the documents, and base her decision on the extent to which the documents are (dis)similar to each other.