Parsing Free Word-Order Languages in Polynomial Time

Long-Distance Scrambling is a word-order phenomenon which is “doubly unbounded” in that (i) more than one element can move, and (ii) movement can be unbounded. In (Becker et al., 1991), we argue that scrambling is beyond TAG by assuming that elementary trees express a complete predicate-argument structure. In (Becker et al., 1992), we show that no formalism in the class LCFRS (which includes TAG) can derive scrambling. (Becker et al., 1991) proposes two variants of the TAG formalism which can derive scrambling while still preserving most of the desirable properties of TAGs (i.e., an extended domain of locality and the factoring of recursion). However, little is known about the formal and computational properties of those systems. (Rambow, 1994) proposes V-TAG, which is closely related to one of the previously proposed varaiants, but redefines the derivation relation. V-TAG can derive the relevant set of sentences and also cases where scrambling co-occurs with long-distance topicalization (a separate linguistic phenomenon also found in English, in which a single element moves into sentenceinitial position):