Nederhof, Mark-JanSatta, GiorgioShieber, Stuart2008-11-102003Mark-Jan Nederhof, Giorgio Satta, and Stuart M. Shieber. Partially ordered multiset context-free grammars and ID/LP parsing. In Proceedings of the Eighth International Workshop on Parsing Technologies, pages 171-182, Nancy, France, April 2003.http://nrs.harvard.edu/urn-3:HUL.InstRepos:2252599We present a new formalism, partially ordered multiset context-free grammars (poms-CFG), along with an Earley-style parsing algorithm. The formalism, which can be thought of as a generalization of context-free grammars with partially ordered right-hand sides, is of interest in its own right, and also as infrastructure for obtaining tighter complexity bounds for more expressive context-free formalisms intended to express free or multiple word-order, such as ID/LP grammars. We reduce ID/LP grammars to poms-grammars, thereby getting finer-grained bounds on the parsing complexity of ID/LP grammars. We argue that in practice, the width of attested ID/LP grammars is small, yielding effectively polynomial time complexity for ID/LP grammar parsing.en-US