  The text-critical practice of grouping witnesses into families or texttypes
often faces two obstacles: Contamination in the manuscript tradition, and
co-dependence in identifying characteristic readings and manuscripts. We
introduce non-negative matrix factorization (NMF) as a simple, unsupervised,
and efficient way to cluster large numbers of manuscripts and readings
simultaneously while summarizing contamination using an easy-to-interpret
mixture model. We apply this method to an extensive collation of the New
Testament epistle of Jude and show that the resulting clusters correspond to
human-identified textual families from existing research.
