Dependency grammar has a long tradition in syntactic theory, dating back to at least Tesniere's work from the thirties.~1 Recently, it has gained renewed attention as empirical methods in parsing are discovering the importance of relations between words (see, e.g., (Collins, 1997)), which is what dependency grammars model explicitly do, but context-free phrasestructure grammars do not. One problem that has posed an impediment to more wide-spread acceptance of dependency grammars is the fact that there is no computationally tractable version of dependency grammar which is not restricted to projectiue analyses. However, it is well known that there are some syntactic phenomena (such as wh-movement in English or clitic climbing in Romance) that require nonprojective analyses. In this paper, we present a form of projectivity which we call pseudoprojectiuity, and we present a generative stringrewriting formalism that can generate pseudoprojective analyses and which is polynomially parsable.
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