In the syntactic parsing model which uses rulebased grammar, the probability of a parsing tree can be defined as the probability of the derivation which generates the current parsing tree for the given sentence.
denotes a derivation rule sequence, h i denotes the partial parsing tree derived from In order to accurately estimate the parameters, we need to select some feature types , depending on which we can divide the contextual condition According to the equation of (2) and (3), we have the following equation: In this way, we can get a unite expression of probabilistic evaluation model for statistical syntactic parsing.