1. A method comprising: identifying a sentence; identifying a graph of generalized constituents of the sentence based on rough syntactic analysis of a lexical-morphological structure of the sentence, wherein the graph of generalized constituents comprises arcs and nodes, wherein each of the nodes represents a constituent of the sentence comprising one or more words in the sentence that function as a unit within the sentence, and wherein each of the arcs between a pair of the nodes represents a syntactic slot expressing a type of relationship between lexical values of the pair; filtering, by a data processing apparatus, the arcs of the graph of generalized constituents using a combination classifier comprising a tree classifier and at least one linear classifier, wherein the tree classifier divides the arcs into clusters based on a predetermined set of symbolic features, and wherein the linear classifier filters the clusters of the arcs based on combinations of numerical features for each of the clusters; and identifying, by the data processing apparatus, a syntactic structure of the sentence by performing precise syntactic analysis of the sentence based on the graph of generalized constituents of the sentence with the filtered clusters of the arcs.