, is the normalized discount. The second term, |{w : C(w i−1 w) > 0}|, is the number of word types that can follow w i−1 or, equivalently, the number of word types that we discounted; in other words, the number of times we applied the normalized discount. The general recursive formulation is as follows: The continuation count is the number of unique single word contexts for •. At the termination of the recursion, unigrams are interpolated with the uniform distribution, where the parameter is the empty string: