The weight η is the distortion penalty.
input: in addition, define singles(j) to be the set of phrases that translate the single word at position j: singles(j) = {p : s(p) = j and t(p) = j} Next, define h to be the smallest integer such that for all j, |first(j)| ≤ h, |last(j)| ≤ h, and |singles(j)| ≤ h. h is a measure of the maximal ambiguity of any word x j in the input.