On The Complexity Of ID/LP Parsing
نویسنده
چکیده
Modern linguistic theory attributes surface complexity to interacting subsystems of constraints. For instance, the ID/LP grammar formalism separates constraints on immediate dominance from those on linear order. An ID/LP parsing algorithm by Shieber shows how to use ID and LP constraints directly in language processing, without expanding them into an intermediate context-free "object grammar". However, Shieber's purported runtime bound underestimates the difficulty of ID/LP parsing. ID/LP parsing is actually NP-complete, and the worst-case runtime of Shieber's algorithm is actually exponential in grammar size. The growth of parser data structures causes the difficulty. Some computational and linguistic implications follow; in particular, it is important to note that, desplte its potential for combinatorial explosion, Shieber's algorithm remains better than the alternative of parsing an expanded object grammar.
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تاریخ انتشار 1985