Grammars for local and long dependencies
Alexander Dikovsky · 2001
Polarized dependency (PD-) grammars are proposed as a means of efficient treatment of discontinuous constructions. PD-grammars describe two kinds of dependencies: local, explicitly derived by the rules, and long, implicitly specified by negative and positive valencies of words. If in a PD-grammar the number of non-saturated valencies in derived structures is bounded by a constant, then it is weakly equivalent to a cf-grammar and has a O(n3)-time parsing algorithm. It happens that such bounded PD-grammars are strong enough to express such phenomena as unbounded raising, extraction and extraposition.