The morphology assigns a probability to each word w as the product of the probability of w's signature times w's stem, given its signature, and w's suffix, given its signature: prob (w = t +f) = prob (c 0 prob (t I or) prob (f ] or), where cr is the signature associated with t: cr = sig(t).
while stems and suffixes, which are defined relative to a particular morphological model, are assigned their empirical frequency as their probability, words are assigned a probability based on the model, one which will always depart from the empirical frequency.