NP Gerunds

NP gerunds show a number of structural peculiarities, the crucial one being that they have the internal properties of sentences. In the English XTAG grammar, we adopt a position similar to that of [#!Rosenbaum67!#] and [#!Emonds70!#] - that these gerunds are NP's exhaustively dominating a clause. Consequently, the tree assigned to the transitive NP gerund tree (cf. Figure 17.2) looks exactly like the declarative transitive tree for clauses except for the root node label and the feature values. The anchoring verb projects a VP. Auxiliary adjunction is allowed, subject to one constraint - that the highest verb in the verbal sequence be in gerundive form, regardless of whether it is a main or auxiliary verb. This constraint is implemented by requiring the topmost VP node to be <mode> = ger. In the absence of any adjunction, the anchoring verb itself is forced to be gerundive. But if the verbal sequence has more than one verb, then the sequence and form of the verbs is limited by the restrictions that each verb in the sequence imposes on the succeeding verb. The nature of these restrictions for sentential clauses, and the manner in which they are implemented in XTAG, are both discussed in Chapter 20. The analysis and implementation discussed there differs from that required for gerunds only in one respect - that the highest verb in the verbal sequence is required to be <mode> = ger.

   

Figure: NP Gerund tree from the transitive tree family: $\alpha$Gnx0Vnx1

$\alpha$Gnx0Vnx1

Additionally, the subject in the NP gerund tree is required to have <case>=acc/none/gen, i.e., it can be either a PRO (cf. example (263)), a genitive NP (cf. example (264)), or an accusative NP (cf. example (265)). The whole NP formed by the gerund can occur in either nominative or accusative positions.

(262)0(262

(263)

...John does not like wearing a hat.  (263)0(263

(264)

Are private markets approving of Washington's bashing Wall Street?  (264)0(264

(265)

Mother disapproved of me wearing such casual clothes. 

One question that arises with respect to gerunds is whether there is anything special about their distribution as compared to other types of NP's. In fact, it appears that gerund NP's can occur in any NP position. Some verbs might not seem to be very accepting of gerund NP arguments, as in ((266)) below, but we believe this to be a semantic incompatibility rather than a syntactic problem since the same structures are possible with other lexical items.

(265)0(265

(266)

? [_NPJohn's tinkering_NP] ran.  (266)0(266

(267)

[_NPJohn's tinkering_NP] worked. 

By having the root node of gerund trees be NP, the gerunds have the same distribution as any other NP in the English XTAG grammar without doing anything exceptional. The clause structure is captured by the form of the trees and by inclusion in the tree families.