Practical Grammar 10

Infinitives

Having dealt with complements in the form of NP, PP, and subordinate clauses, we now turn to infinitives. Here are a few typical examples:

(1) Ingrid tried [to buy olives]
(2) Ingrid pursuaded Fred [to buy olives]
(3) Ingrid promised Fred [to buy olives]

Let us investigate the meaning of these sentences first. 'buy' is a predicate that needs an AGENT and a PATIENT. The patient in each of the sentences above is mentioned directly: olives. But who is the agent? As is shown by the following (not always natural sounding) paraphrases, in (1) and (3), Ingrid is understood to be the one buying olives and in (2) Fred is understood as the intended olive buyer

(1b) Ingrid tried to bring it about that she (= Ingrid) buys olives.
(2b) Ingrid pursuaded Fred that he (= Fred) buys olives.
(3b) Ingrid promised Fred that she (= Ingrid) buys olives.

Interestingly, even though a. there is an understood agent in each case and b. buy assigns the agent role to its subject, this subject cannot be expressed inside the infinitive. An attempt to add one, for instance as a pronoun leads to ungrammaticality:

(1c) * Ingrid tried [she to buy olives]
(2c) * Ingrid pursuaded Fred [he to buy olives]
(3c) * Ingrid promised Fred [she to buy olives]

As the examples above show, the understood subject of the infinitive is not always the same. That naturally raises the question of how the interpretation of the understood subject is determined.

A little thought shows that the understood subject of the infinitive is determined by the (meaning of) the upper verb. When one tries or promises to do something, then one does so for an action that one will perform oneself. On the other hand, when one persuades somebody to do something, it is the pursuaded person that is supposed to perform the action, not the pursuader. The phenomenon that we witness here is called Control. We say that try and promise make their subject control the infinitive, whereas pursuade makes its the object to control the infinitive.

These are the facts that we wish to capture in this unit. As always, we will need lexical entries and annotated phrase structure rules to accomplish that. Here are some guiding ideas to help you do that.

Guiding ideas

1. The infinitive marker to can be assumed to belong to part of speech V (for infinitive marker).
2. The infinitive buy is a new type of verb form for us. So far, all the verb forms that we encountered were tensed forms in the present and past tense, e.g. the third person singular present tense form buys or the non-third person singular present tense form buy, as in I buy olives, you buy olives, etc. Note that even though the non-third person singular tense forms and the infinitives of most verbs are homophonous (= are pronounced the same way), they must be kept distinct. They have different grammatical properteis and for some verbs, they are not homophonous. Note, for instance, I am, you are vs. to be!
3. To separate these finite and infinitival verb forms from each other, we introduce a new feature called VFORM, with the values "fin" (= finite = tensed) and "inf" (= infinitive = non-tensed). There will eventually also be VFORM values for progressive verb forms like buying and participles like bought, but we will not deal with those here.
4. As always, when we introduce a new kind of argument (in this case the infinitive), we need to specify a grammatical function for it. For tensed subordinate clauses we chose the grammatical function COMP (= complement clause). For infinitival complements we postulate the grammatical function XCOMP. The X stands for the unexpressed subject inside the infinitive complement.

In the following exercises, we will extend the grammar to license sentences with verbs like 'try' and 'persuade' which have interesting properties.

Subject control: try

Notation:

In the exercises of this unit, we will have to implement Control: this means that a GF of the higher verb and the SUBJ of the higher verb's XCOMP are identical.

In XLFG, this is written as follows:

• (↑SUBJ) = (↑XCOMP SUBJ); means: the SUBJ of the higher verb and the XCOMP's SUBJ are identical.
• (↑OBJ) = (↑XCOMP SUBJ); means: the OBJ of the higher verb and the XCOMP's SUBJ are identical.

Note: remember to use the up and down arrows from the XLFG editor rather than those from your keyboard!

Exercise 10.1

• Go to https://xlfg.labri.fr/.
• Make all the additions to the grammar that are necessary to yield the following outputs for sentence (1), repeated below:

(1) Ingrid tried to buy olives.

Implement the following grammatical assumptions:

• 'to' (the infinitive marker): assume that it is a verb which is marked [IM:+].
• 'buy': [VFORM:INF]

Make sure that your grammar also makes the correct predictions for the sentences below:

(2) Ingrid buys olives
(3) *Ingrid tried buys olives

Object control: persuade

try is a subject control verb, because the controller of the lower subject is the higher subject. But, objects can control as well. One verb where that is the case is persuade.

Exercise 10.2

Make all the changes to your current grammar so that it licenses the representations for (2) below:

(2) Ingrid persuaded Fred to buy olives.

Make sure that your grammar makes the correct predictions for the sentences below:

(2) Ingrid buys olives
(3) *Ingrid persuaded Fred buys olives

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