Adjunct relative clauses

Two types of trees to handle adjunct relative clauses exist in the XTAG grammar: one in which there is PP_w substitution with a null Comp built in and one in which there is a null NP_w built in and a Comp substitutes in. There is no NP_w substitution tree with a null Comp built in. This is because of the contrast between ((263)) and ((264)).

(262)0(262

(263)

the day [[on whose predecessor] [_C [Muriel left]]]  (263)0(263

(264)

*the day [[whose predecessor] [_C [Muriel left]]] 

In general, adjunct relatives are not possible with an overt NP_w. We do not consider ((265)) and ((266)) to be counterexamples to the above statements because we consider where and when to be exhaustive PPs that head a PP initial tree.

(264)0(264

(265)

the place [where [_C [Muriel wrote her first book]]]  (265)0(265

(266)

the time [when [_C [Muriel lived in Bryn Mawr]]]