Embedded Clauses in TAG

Embedded Clauses

We think that they have left.

COMP NP VP

S

V S-bar

NP VP

S

Embedded Clause

Matrix Clause

Linguistic Background

• Constraints

• Semantic roles

Embedded Clauses: Constraints

• Main verbs are subcategorized for – The complementizer (that, for, to, etc.) Non-

finite for-to – We hoped for there to be no trouble.

• A word at the beginning of a subordinate clause that identifies it as a complement

– The morphology of the embedded verb• Finite: present or past tense• Non-finite: infinitive, present participle, past

participle

Examples: Constraints imposed by the main verb on the embedded verb

• “Say” requires a finite embedded clause:– Sam said that Sue saw him.– *Sam said Sue to see him.– *Sam said that Sue seeing him.

• “that” is a complementizer that goes with finite clauses. When it comes after a verb, it is optional:– Sam said Sue saw him.– That he left is a problem.– *He left is a problem.

• “That” is only optional after a verb.

Examples: Constraints imposed by the main verb on the embedded verb

• “Expect” takes a finite clause or an infinitive, but not a participle:– We expect to see him.– We expect that we will see him.

• Modal auxiliary verbs (will, would, may, might, can, could, shall, should, etc) are always finite.

– *We expect seeing him.• Might sound grammatical because “seeing him” can be a

noun phrase, and “expect” can occur with a noun phrase: “We expect problems”

– *We expect seen him.

Finite embedded clauses

• Finite embedded clause– I believe (that) it is snowing.– Say, think, scream

• Finite with dummy subject– It seems that they have left.

• Finite embedded question– I wondered/asked whether/if it was snowing.

• Finite plus object– We told them that it was snowing.

• Finite plus PP– We said to them that it was snowing.

Non-finite embedded clauses• Non-finite for-to

– We hoped for there to be no trouble.• Non-finite: Raising to subject

– They seem (to us) to have left.– Appear, continue

• Non-finite: Subject Equi– They tried to leave.– Intend, expect, plan, hope

• Non-finite: Raising to object– We believe them to have left.– consider

• Non-finite: Object Equi– We persuaded them to leave.– Convince, order, force, signaled

• Non-finite: promise– We promised them to leave.

English Auxiliary Verbs

• Modal verbs: (will, would, can, could, shall, should, may, might, and a few others)– Invariant: don’t have a third person singular form.– Only occur where you can have present or past tense. Don’t

occur in infinitives, gerunds, or participles:• I will go.• I would go.• I said I would go.• *I want to can go.

– Compare: I want to be able to go.• *Canning go would make me happy.

– Compare: Being able to go would make me happy.– The next verb must be an infinitive without “to”.

• I will have gone.• I will be going.• *I will going/gone/went/goes.

English Auxiliary Verbs

• “Have”– Must be followed by a past participle:

• I have gone.• *I have going/went/goes/go.

• Progressive “be”– Must be followed by a present participle:

• I am going.• *I am goes/went/go.

• Passive “be”– Must be followed by a passive verb:

• The cookies were devoured.• *The cookies were devouring/devours/devour.

Auxiliary verbs as main verbs(for syntax; not for semantics)

• The auxiliary verb can impose constraints on the main verb.– Sam is sleeping/*slept/*sleeps.

• The main clause has to be finite (has a tense). – Sam sleeps/slept.– *Sam to sleep.– *Sam sleeping.

• The auxiliary verb carries the tense, not the main verb:– Sam is sleeping.– *Sam be sleeps.

S

Sam is sleeping

NP VP

V VP

S

Sam has slept

NP VP

V VP

Summary of constraints on embedded clauses

• The main verb determines the tense and morphology of the embedded verb.

• More than one embedded clause:– Each verb determines the tense and

morphology of the next one:• I think that Sam tried to sleep. • “Think” requires “try” to be finite.• “Try” requires “sleep” to be infinitive.

The car needs washed.

• In most dialects of English, “need” takes an infinitive as a complement:– The car needs to be washed.– Sam needs to sleep.

• There are a few verbs that take passive participles as complements:– We had them arrested by the police.– We got them arrested by the police.– They were arrested by the police.– They got arrested by the police.

• In Pittsburgh, “need” and “want” can take passive participles as complements:– The car needs washed.– Do you want pushed?

Semantic Roles

• Syntax– Word order– Constituent structure– Constraints: agreement, subcategorization,

case marking– Semantic roles:

• Sue interviewed Sam.• Sue is the interviewer.• Sam is the interviewee.

Semantic Roles in Embedded Clauses

• Sam tried to sleep.– Sam is the agent of “try”– Sam is the agent of “sleep”– “Sam to sleep” is what was tried.

• Sam seemed to sleep.– Sam is the agent of “sleep.”– Sam is not an argument of “seem.”– “Sam to sleep” is the only argument of

“seem”.

Just the facts

• How many semantic arguments does each verb take:– “Try” takes two.– “Seem” takes one.

• Do the main clause and the embedded clause share a subject?– Yes. Both “seem” and “try” share their

subjects with the embedded verb.

How we know that the semantic role assignments are different with Seem and Try

• The cat seems to be out of the bag.

• There seems to be a problem.

• That seems to be my husband.

• The doctor seemed to examine Sam.

• Sam seemed to be examined by the doctor.

• The cat tried to be out of the bag.

• *There tried to be a problem.

• That tried to be my husband.

• The doctor tried to examine Sam.

• Sam tried to be examined by the doctor.

Raising to subject

It seems that they have left.

COMP NP VP

S

V S-bar

NP VP

S

They seem to have left.

COMP

VP

V VP-bar

NP VP

S

They seem to have left.

COMP

VP

V VP-bar

NP VP

S

They seem e to have left.

NP VP

V S

NP VP

S

Two ways to represent that “seem” and “leave” share a subject.

Subj theyVerb seemComplement subj verb leave

Comparison• Second method:

– Allow empty strings as terminal nodes in the tree. – An empty string needs to take the place of the missing subject of the

lower clause.– The empty string is linked to the subject of the main clause to show that

the main and embedded clauses share a subject.– The tree represents: word order, constituent structure, grammatical

relations, semantic roles.• First method:

– No empty strings in the tree. – The tree represents only word order and constituent structure.– Grammatical relations and semantic roles are represented in a separate

structure.– Structure sharing in the representation of grammatical relations shows

that the two verbs share a subject. • Is one method simpler than the other?

– No. Both methods have to represent word order, semantic relations, grammatical relations, and semantic roles.

• People who argue that one is simpler are usually wrong – they don’t know how to count steps in a derivation.

They try to leave.

COMP

VP

V VP-bar

NP VP

S

They(i) try PRO(i) to leave.

NP VP

V S

NP VP

S

Two ways to represent that “try” and “leave” share a subject.

Subj theyVerb seemComplement subj verb leave

PRO is an empty string, but not the same kind of empty string as e

Coindexing indicates that PRO refers to “they”.

“Seem” type verbs in TAG

S

John to be happy

V AP

NP VP V VP

VP

seem

Initial Tree

Auxiliary Tree

These trees represent the number of arguments for each verb:

“Seem” has one argument, represented as a VP.

“To be happy” has one argument, “John”.

Adjunction site

S

NP VP

to be happy

V AP

VP

John

V VP

VP

seem

Adjunction site

to be happy

V AP

VP

S

NP VP

John

V VP

VP

seem

Adjunction

V VP

VP

seems

to be happy

V AP

S

NP

John

This tree shows word order and constituent structure.

It also shows that “John” is the subject of “seem.”

It doesn’t show that “John” is the subject of “to be happy.”

“Try” type verbs in TAG

S

V S

NP VP

John tried

S

NP VP

TO VP

PRO leave

Adjunction site

These trees show the number of arguments for each verb:

“Try” has two arguments.

“Leave” has one argument.

Initial Tree

Auxiliary Tree

S

NP VP

TO VP

PRO leave

SAdjunction site

S

V S

NP VP

John tried

S

NP VP

TO VP

PRO leave

SAdjunction site

S

V S

NP VP

John tried

S

NP VP

TO VP

PRO leave

S

V

NP VP

John tried

Adjunction is only allowed at the top S node so as not to mess up compositional semantics:

After you put together “try to leave” you don’t want to have to take it apart again by inserting another verb like “expected” as in:

John tried to expect to leave.

Inserting “seem” into the middle of the tree doesn’t require you to disassemble any of the semantic pieces that were already assembled?