7. The non-transitory storage medium of claim 1 wherein the optimizing is performed using a proximal step algorithm.
7. The non-transitory storage medium of claim 1 wherein the optimizing is performed using a proximal step algorithm. 9. The non-transitory storage medium of claim 7 wherein the penalty Ω(W) comprises l ∞ T (w)=Σ jε ∥g(w,j)∥ ∞ where ∥•∥ ∞ denotes the l ∞ -norm, g(w,j) is the sub-vector of w associated with the subtree rooted at node j of the suffix trie of a language sample of the corpus, and is an ordered set of nodes of the suffix trie.