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]

The bracketed infinitives differ from COMPs in three major ways:

1. The form of the verb is an infinitive;
2. The infinitive marker to appears before the verb.
3. The infinitive lacks an overt SUBJ.

Let us investigate the meaning of these sentences. 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 object 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. We analyze infinitival subordinate clauses as VPs.
2. The infinitive marker to can be assumed to belong to part of speech IM (for infinitive marker). That is all the lexicon needs to say about it.
3. Assume that IM combines with a VP to form another VP. IM and its sister VP are co-heads of their mother-VP.
4. 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 properties and for some verbs, they are not homophonous. Note, for instance, I am, you are vs. to be!
5. 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.
6. As always, when we introduce a new expression kind (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 of the subordinate clause.

How to write the control equations in XLFG

Each control verb contains a control equation that expresses which of the control verb's arguments controls the understood SUBJ of the control verb's XCOMP. Below, the equations for SUBJ and OBJ control are stated.

Note:

a. Remember to use the up arrow from the editor, not those from your keyboard.
b. The control equations must occur in curled parentheses at the end of the lexical entry.
c. There is no semicolon before { !
d. There is a semicolon after } !

Subject control: try and promise

The SUBJ of the higher verb and the XCOMP's SUBJ are identical:
{ (↑SUBJ) = (↑XCOMP SUBJ); };

Object control: persuade

 The OBJ of the higher verb and the XCOMP's SUBJ are identical.
 { (↑OBJ) = (↑XCOMP SUBJ); };

Also note: if necessary, there may be additional statements inside the curly brackets besides the control equations. Every such statement also ends with a semicolon!

In the following exercise, we will extend the grammar to license sentences with verbs like try, promise, and persuade.

Exercise 10 Controlled infinitival complement clauses

1. Go to https://xlfg.labri.fr/ and log in.
2. Open Exam Grammar SoSe 2026.
3. The grammar contains 14 test sentences.
4. Add lexical entries and phrase structure rules so that your grammar makes the correct grammaticality predictions for all 14 test sentences.

Important note: the Wiki page currently does not allow me to upload pictures. Therefore, I have uploaded to Olat the file

Exercise-10-expected-output.pdf

which presents the structures that your grammar should produce for 14 test sentences.

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