18.5.3 Verb Phrases

The general schema for computing the semantics of verb phrases relies on the notion of function application. In most cases, the $ \lambda $-expression attached to the verb is simply applied to the semantic attachments of the verb's arguments. There are, however, a number of situations that force us to depart somewhat from this general pattern.

Infinitive Verb Phrases

A fair number of English verbs take some form of verb phrase as one of their arguments. This complicates the normal verb phrase semantic schema since these argument verb phrases interact with the other arguments of the head verb in ways that are not completely obvious.

Consider the following example:

(18.19) I told Harry to go to Maharani.

The meaning representation for this example should be something like the follow-

ing:

$$ \begin{array}{l}\exists e,f,x Isa(e,Telling)\land Isa(f,Going)\\\quad\land Teller(e,Speaker)\land Tellee(e,Harry)\land ToldThing(e,f)\\\quad\land Goer(f,Harry)\land Destination(f,x)\end{array} $$

There are two interesting things to note about this meaning representation: the first is that it consists of two events, and the second is that one of the participants, Harry, plays a role in both of the two events. The difficulty in creating this complex representation falls to the verb phrase dominating the verb tell which will need something like the following as its semantic attachment:

$$ \begin{array}{l}\lambda x,y\;\lambda z\;\exists e\;Isa(e,Telling)\\ \quad\land Teller(e,z)\land Tellee(e,x)\land ToldThing(e,y)\end{array} $$

Semantically, we can interpret this subcategorization frame for Tell as providing three semantic roles: a person doing the telling, a recipient of the telling, and the proposition being conveyed.

The difficult part of this example involves getting the meaning representation for the main verb phrase correct. As shown in Figure 18.5, Harry plays the role of both the Tellee of the Telling event and the Goer of the Going event. However, Harry is not available when the Going event is created within the infinitive verb phrase.

Although there are several possible solutions to this problem, it is usually best to stick with a uniform approach to these problems. Therefore, we will start by simply applying the semantics of the verb to the semantics of the other arguments.

of the verb as follows:

$$ VP\rightarrow Verb~NP~VPto\qquad\{Verb.sem(NP.sem,~VPto.sem)\} $$

Since the to in the infinitive verb phrase construction does not contribute to its meaning, we simply copy the meaning of the child verb phrase up to the infinitive verb phrase. Recall, that we are relying on the unseen feature structures to ensure that only the correct verb phrases can be used with this construction.

$$ VPto\ \to\ to\ VP\qquad\{VP.sem\} $$

In this solution, the verb's semantic attachment has two tasks: incorporating the NP.sem, the Goer, into the VPto.sem, and incorporating the Going event as the ToldThing of the Telling. The following attachment performs both tasks:

$$ \begin{array}{c}Verb\rightarrow tell\\\left\{\lambda x,y\atop\lambda z\end{array}\exists e,y.variable~Isa(e,Telling)\\\land Teller(e,z)\land Tellee(e,x)\\\land ToldThing(e,y.variable)\land y(x)\end{array} $$

In this approach, the $ \lambda $-variable x plays the role of the Tellee of the telling and the argument to the semantics of the infinitive, which is now contained as a $ \lambda $-expression in the variable y. The expression $ y(x) $ represents a $ \lambda $-reduction that inserts Harry into the Going event as the Goer. The notation y.variable, is analogous to the notation used for complex-term variables, and gives us access to the event variable representing the Going event within the infinitive's meaning representation.

Note that this approach plays fast and loose with the definition of $ \lambda $-reduction, in that it allows $ \lambda $-expressions to be passed as arguments to other $ \lambda $-expressions, when technically only FOPC terms can serve that role. This technique is a convenience similar to the use of complex-terms in that it allows us to temporarily treat complex expressions as terms during the creation of meaning representations.