Again the observational tests used for alignment are: (1) exact token match tests whether the source-target tokens are string identical, (2) approximate token match produces a binary feature after binning the Jaro-Winkler edit distance (Cohen et al., 2003) between the tokens, (3) substring token match tests whether one token is a substring of the other, (4) prefix token match returns true if the prefixes match for lengths {1, 2, 3, 4}, (5) suffix token match returns true if the prefixes match for lengths {1, 2, 3, 4}, and (6) exact and approximate token matches at offsets {−1, −1} and {+1, +1} around the alignment.
a conditional model lets us use these arbitrary helpful features that cannot be exploited tractably in a generative model.