For each character u, we block sample the entire set {λ (u,h) } h , and likewise for each character h. Many of the steps detailed above involve the consideration of all possible edit-sequences consistent with (i) a particular undeciphered word u i and (ii) the entire lexicon of words in the known language (or some subset of words with a particular part-of-speech).
we need to both sample from and sum over this space of possibilities repeatedly.