I am implementing the Inside-outside algorithm to estimate the parameters of a PCFG based on the train corpus. One observation (on existing implementations) is that, the grammar is converted into Chomsky normal form (binarization) prior to the Expectation-Maximization (EM) step.
However, checking the EM formula, I feel the algorithm can work perfectly without the binarization. Thus, I would like to ask if the binarization step is compulsory, or it is to enhance the performance, or it is just to make the formula clean.
Thanks!