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There are three basic types of prepositional phrases, and three places at which they can adjoin. The three types of prepositional phrases are: Preposition with NP Complement, Preposition with Sentential Complement, and Exhaustive Preposition. The three places are to the right of an NP, to the right of a VP, and to the left of an S. Each of the three types of PP can adjoin at each of these three places, for a total of nine PP modifier trees. Table 19.1 gives the tree family names for the various combinations of type and location. (See Section 23.4.2 for discussion of the $\beta $spuPnx, which handles post-sentential comma-separated PPs.)
Table 19.1: Preposition Anchored Modifiers
  position and category modified
  pre-sentential post-NP post-VP
Complement type S modifier NP modifier VP modifier
S-complement $\beta $Pss $\beta $nxPs $\beta $vxPs
NP-complement $\beta $Pnxs $\beta $nxPnx $\beta $vxPnx
no complement $\beta $Ps $\beta $nxP $\beta $vxP

The subset of preposition anchored modifier trees in Figure 19.9 illustrates the locations and the four PP types. Example sentences using the trees in Figure 19.9 are shown in ((303))-((306)). There are also more trees with multi-word prepositions as anchors. Examples of these are: ahead of, contrary to, at variance with and as recently as.
Figure: Selected Prepositional Phrase Modifier trees: $\beta $Pss, $\beta $nxPnx, $\beta $vxP and $\beta $vxPPnx
\includegraphics[height=1.5in]{/mnt/linc/xtag/work/doc/tech-rept/ps/modifiers-files/}   \includegraphics[height=1.5in]{/mnt/linc/xtag/work/doc/tech-rept/ps/modifiers-files/}   \includegraphics[height=1.5in]{/mnt/linc/xtag/work/doc/tech-rept/ps/modifiers-files/}   \includegraphics[height=1.75in]{/mnt/linc/xtag/work/doc/tech-rept/ps/}
$\beta $Pss   $\beta $nxPnx   $\beta $vxP   $\beta $vxPPnx

[PP with Clove healthy PP], the veterinarian's bill will be more affordable . ($\beta $Pss19.4)  (303)0(303
The frisbee [PP in the brambles PP] was hidden . ($\beta $nxPnx)  (304)0(304
Clove played frisbee [PP outside PP] . ($\beta $vxP)  (305)0(305
Clove played frisbee [PP outside of the house PP] . ($\beta $vxPPnx) 

Prepositions that take NP complements assign accusative case to those complements (see section for details). Most prepositions take NP complements. Subordinating conjunctions are analyzed in XTAG as Preps (see Section 15 for details). Additionally, a few non-conjunction prepositions take S complements (see Section 8.8 for details).

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Next: Adverbs Up: Modifiers Previous: Time Noun Phrases
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