Head-Driven Parsing

There are clear signs of a "Back to Basics" movement in parsing and syntactic generation. Our Latin teachers were apparently right. You should start with the main verb. This will tell you what kinds of subjects and objects to look for and what cases they will be in. When you come to look for these, you should also stan by trying to find the main word, because this will tell you most about what else to look for. In the early days of research on machine translation, Paul Garvin advocated the applicadon of what he called the "Fulcrum" method to the analysis of sentences. If he was the last to heed the injunctions of his Latin teacher, it is doubtless because America followed the tradition of rewriting systems exemplified by context-free grammar and this provided no immediate motivation for the notion of the head of a construction. The European tradition, and particularly the tradition of Eastern Europe, where Garvin had his roots, tend more towards dependency grammar, but away from that of mathematical formalization which has been the underpinning of computational linguistics. But the move now is towards linguistic descriptions that put more information in the lexicon so that grammar rules take on a more schematic quality. Little by little, we moved from rules like