Noun-Noun Modifiers

Noun-noun compounding in the English XTAG grammar is very similar to adjective-noun modification. The noun modifier tree, shown in Figure 19.3, has essentially the same structure as the adjective modifier tree in Figure 19.1, except for the syntactic category label of the anchor.

  

Figure: Noun-noun compounding tree: $\beta$Nn (not all features displayed)

Noun compounds have a variety of scope possibilities not available to adjectives, as illustrated by the single bracketing possibility in ((291)) and the two possibilities for ((292)). This ambiguity is manifested in the XTAG grammar by the two possible adjunction sites in the noun-noun compound tree itself. Subsequent modifying nouns can adjoin either onto the N_r node or onto the N anchor node of that tree, which results in exactly the two bracketing possibilities shown in ((292)). This inherent structural ambiguity results in noun-noun compounds regularly having multiple derivations. However, the multiple derivations are not a defect in the grammar because they are necessary to correctly represent the genuine ambiguity of these phrases.

(290)0(290

(291)

[_N big [_N green design _N]_N] 

(291)0(291

(292)

[_N computer [_N furniture design _N]_N]
  [_N [_N computer furniture _N] design _N] 

Noun-noun compounds have no restriction on number. XTAG allows nouns to be either singular or plural as in ((293))-((295)).

(292)0(292

(293)

Hyun is taking an algorithms course .  (293)0(293

(294)

waffles are in the frozen foods section .  (294)0(294

(295)

I enjoy the dog shows .