Prepositional phrases (PPs) which modify verb phrases contribute semantic content which is consistent (unchanging) across uses and identifiable. Their interpretation is, however, constrained by the lexical semantic structure of the modified phrase. In this chapter, I will investigate the treatment of the semantic contribution of prepositional phrases in HPSG, with particular reference to dative PPs. Dative PPs are those PPs which participate in the dative alternation. There are two basic kinds: -datives, which appear in the two alternate forms shown in exp1, and -datives, as shown in exp2.
John gave a book to Mary. John gave Mary a book.
John baked a cake for Mary. John baked Mary a cake.
Such PPs have traditionally been treated as having little semantic content independent of the verbs with which they appear. I will argue that the consistency of their semantic content suggest that a compositional analysis of their contribution is more appropriate. I will show that the overall interpretation of a sentence containing a VP-modifying PP can only be determined by an interaction of the semantics of the VP and the semantics of PP, and certain principles governing this interaction. I will end the chapter by introducing a general account of the semantic function of PPs, and by extension also of other entities which can function as semantic obliques in a sentence, which takes into consideration the different ways that they can interact with the semantic content of the sentence in which they appear.
Dative prepositional phrases provide an interesting testing ground for investigating various syntactic and semantic properties of prepositional phrases because they have traditionally been viewed (e.g. Jackendoff 1990, Verspoor 1994) as elements which are subcategorised by the verbs with which they appear and as having very little meaning independent of those verbs. The prepositions are viewed as markers for particular semantic roles. This view derives from analogous phenomena in other languages, such as German, in which these semantic roles are introduced by (dative) case-marking on the nouns which fill the same position as the PPs in English.
More generally, a distinction has traditionally been drawn between prepositional phrases which behave as verbal complements, i.e. which participate in the main relation expressed by the verb (like the dative PPs), and those which are adjuncts, introducing information which helps to contextualise or situate more precisely an eventuality expressed by a sentence. I introduced this distinction in Chapter 2, Section 2.5.1, and incorporated a representational distinction between internal and external semantics to accommodate the integration of the semantics of the different kinds of modifying phrases (via internal predication or external predication). An example of the distinction can be found by comparing exp1a with d100.
The PP to Mary in exp1a introduces an entity which plays a central role in the semantics of giving -- the role of recipient. This PP is therefore considered to be a (subcategorised) complement of the verb. The PP in the park in d100, in contrast, does not introduce a central entity in the semantic relation expressed by the main verb. Instead it simply provides location information about the event expressed in the main clause, and is treated as an (unsubcategorised) adjunct.
It is arguable that the class of verbal complements is divisible further. gawron:86 identifies argument PPs, in which a preposition marks a verbal argument, and co-predicating PPs, which introduce a new argument and thereby extend the main verbal relation. Every use of a preposition, however, contributes the same lexical content. It is only the manner in which that lexical content interacts with the content of the modified phrase which varies. This analysis provides the basis of a compositional treatment of the semantics of prepositional phrases.
In this chapter, I build on this insight to present a treatment of prepositional phrases which also includes a three-way basic distinction between PP types. But, in contrast to Gawron, I look in further detail at the range of semantic contribution of adjuncts. The distinction in types which I propose differs from that of gawron:86 in that it is driven by syntactic considerations as well as semantic ones. Hence I assume that there are (1) complement PPs in which the preposition marks a verbal argument and is subcategorised by the verb, (2) pseudo-complement PPs, which share certain syntactic properties with complements yet are not introduced by subcategorisation and which can either mark a verbal argument or introduce a new argument and extend the verbal relation, and (3) adjunct PPs which introduce external predication. The pseudo-complements therefore cross-cut the traditional adjunct vs.\ complement distinction, and subsume some of Gawron's argument PPs and some of his co-predicating PPs. The syntactic distinction will be shown to be important for accounting for syntactic optionality of argument PPs without explicitly encoding such optionality in lexical entries.
I introduce mechanisms within HPSG for licensing pseudo-complement and adjunct PPs which accounts for the syntactic properties of co-predicators in contrast to adjuncts as well as their distinct compositional behaviour. In this treatment I, like Gawron, assume a single lexical entry for each preposition. I further rely on the mechanisms licensing the introduction of non-subcategorised PPs for controlling the appropriate semantic interaction. The range of interactions will be seen to depend on the type of the preposition and the lexical semantics of both the PP and the modified phrase.
The chapter begins with an investigation of the status of - and -dative PPs in Section 3.2 -- does the syntactic behaviour of these PPs as verbal complements warrant a treatment of them as essentially semantically void? This will be shown to miss a generalisation about their semantic contribution. I will also show that certain of these PPs must be construed as entities at the level of pseudo-complements, interacting with the main verb's internal semantics.
The integration of the semantics of pseudo-complements with the semantics of the modified entities can be treated in a manner analogous to the treatment for pure adjuncts. However, in Section 3.3 the internal vs. external predication which distinguishes them will be explicitly accommodated in the framework controlling the semantic integration.
Section 3.4 will discuss issues related to the treatment of prepositional phrases in HPSG, including general properties of adjuncts which must be accommodated and the existing HPSG treatments of adjuncts. The existing approaches will be shown to fail in adequately handling certain syntactic and semantic properties of adjuncts. In particular, interactions between surface order and semantic precedence are stumbling blocks for those approaches.
Section 3.5 will propose a framework based on work by kasper:93 and vannoord_bouma:94 which supports integration of the semantic contribution of all PP types. The semantic representation introduced in Chapter 2 provides the foundation for the treatment of both pseudo-complements and adjuncts within the same system. The treatment of the semantic integration is handled via rules which will be explicitly stated and shown to provide a more satisfactory handling of surface order/semantic precedence interactions as well as other properties of the adjuncts. The framework will also be shown to accommodate a treatment of the phenomenon of the dative alternation.
Finally, we will see a brief example of how world knowledge can influence the grammaticality of a sentence. If world knowledge cannot support an interpretation which stems from lexical semantic composition of the components of a sentence, then that sentence is infelicitous.