Set p1 to be the learnt parameter and p0 to be derived from it
Set p1 to be the learnt parameter and p0 to be derived from it

Since p0 + p1 = 1, one can be easily derived given the other. p1 is
really the parameter of interest, which is the probability that a
generated word inserts a NULL-aligned word.

nltk/nltk,nltk/nltk,nltk/nltk