I’m looking for a way to build a hierarchy of categories from a text corpus, unsupervised.

Anyone have an idea how to accomplish this?

For instance, using it on a corpus about animals, it should generate a tree like

mammals mammals>mammals on land birds birds>birds of prey

In an ideal world, the system would be extracting both the category labels themselves and their hierarchy from the text. But even if you had to provide a list of categories, and the system merely used to text corpus to figure out their hierarchy, this would be helpful.