Open Access

Ivan A. Sag

• HPSG accounts of filler-gap dependencies hold considerable potential for explaining the cross-linguistic variation in unbounded dependency constructions (UDCs), specifically filler-gap dependencies. This potential comes from the SLASH specifications that are posited in all nodes along the extraction path (the path between filler and gap). However, as Hukari and Levine (1994, 1995, 1996) have observed, the HPSG analysis presented by Pollard and Sag (1994) fails to embody the generalizations required in order to explain key universal properties of UDCs, in particular the ˋregistration' of such dependencies in cases of subject- and adverb-extraction. This demonstration led Bouma et al. (2001) to propose a revised UDC analysis that avoids these difficulties by ˋthreading' the SLASH specfications through all heads within an extraction domain. However, Levine (2002) points out that this analysis encounters a new difficulty concerning the interaction of extraction and coordination. This paper revisits these issues, arguing that a small modification of the BMS analysis provides a solution to the important problem observed by Levine.