自然语言理解 原文摘录

Roles and Subroles

Other Common Names

Definition

CAUSAL-AGENT

the object that caused the event

AGENT

intentional causation

INSTR

force/tool used in causing the event

THEME

PATIENT

the thing affected by the event

EXPERIENCER

the person involved in perception

or a physical/psychological state

BENEFICIARY

the person for whom an act is done

AT

the state/value on some dimension

AT-LOC

LOCATION

current location

AT-POSS

POSSESSOR

current possessor

AT-VALUE

current value

AT-TIME

current time

TO

final value in a state change

TO-LOC

DESTINATION

final location

TO-POSS

RECIPIENT

final possessor

TO-VALUE

final value

FROM

original value in a state change

FROM-LOC

SOURCE

original location

FROM-POSS

original possessor

FROM-VALUE

original value

PATH

path over which something travels

CO-AGENT

secondary agent in an action

CO-THEME

secondary theme in an exchange

Figure 8.5 Some possible semantic roles

This possibility will not be pursued further, however, since it leads into many issues not relevant to the remainder of this chapter.

Figure 8.5 provides a summary of most of the roles distinguished thus far and the hierarchical relationships between them.

As you've seen, verbs can be classified by the thematic roles that they require. To classify them precisely, however, you must make a distinction between roles that are "intimately" related to the verb and those that are not. For example, almost any past tense verb allows an AT-TIME role realized by the adverb "yesterday". Thus this role is apparently more a property of verb phrases in general than a property of any individual verb. However, other roles – namely, those realized by constituents for which the verb subcategorizes - seem to be properties of the verb. For example, the verb "put"subcategorizes for a PP, and fur­thermore, this PP must realize the TO-LOC role. In verb classification this latter type of role is important, and these roles are called theinner roles of the verb.

The preceding examples suggest one test for determining whether a given role is an inner role for a given verb: if the role is obligatory, it is an inner role. Other inner roles, however, appear to be optional, so other tests are also needed. Another test is based on the observation that all verbs may take at most one NP in

[Allen 1995: Chapter 8 – Semantics and Logical Form / 249]

any given inner role. If multiple NPs are needed, they must be related by a conjunction. Thus you can say

John and I ran to the store.

but not

* John I ran to the store.

Similarly, you can say

I ran to the store and to the bank.

but not

* I ran to the store to the bank.

Thus the AGENT and TO-LOC roles for the verb run are inner roles.

Verbs typically specify up to three inner roles, at least one of which must always be realized in any sentence using the verb. Sometimes a particular role must always be present (for example, TO-LOC with put). Typically, the THEME role is also obligatory, whereas the AGENT role is always optional for any verb that allows the passive form.

There are also syntactic restrictions on how various roles can be realized. Figure 8.6 shows a sample of ways that roles can be realized in different sentences.

The following are some sample sentences with each verb in italics and its argument, whether NP, PP. or embedded 5, classified by its role in order of occurrence:

Jack ran.

AGENT only

Jack ran with a crutch.

AGENT + INSTR

Jack ran with a crutch for Susan.

AGENT + INSTR +BENEFICIARY

Jack destroyed the car.

AGENT + THEME

Jack put the car through the wall.

AGENT + THEME +PATH

Jack sold Henry the car.

AGENT + TO-POSS +THEME

Henry pushed the car from Jack's house to the junkyard.

AGENT + THEME +FROM-LOC + TO-LOC

Jack is tall.

THEME

Henry believes that Jack is tall.

EXPERIENCER + THEME

Susan owns a car.

AT-POSS + THEME

I am in the closet.

THEME + AT-LOC

The ice melted.

THEME

Jack enjoyed the play.

EXPERIENCER + THEME

The ball rolled down the hill to the water.

THEME + PATH +TO-LOC

[Allen 1995: Chapter 8 – Semantics and Logical Form / 250]

Role

Realization

AGENT

as subject in active sentences

preposition by in passive sentences

THEME

as object of transitive verbs

s subject of nonaction verbs

INSTR

as subject in active sentences with no agent preposition with

EXPERIENCER

as animate subject in active sentences with no agent

BENEFICIARY

as indirect object with transitive verbs preposition for

AT-LOC

prepositions in, on, beyond, etc.

AT-POSS

possessive NP

as subject of sentence if no agent

TO-LOC

prepositions to, into

TO-POSS

preposition to, indirect object with certain verbs

FROM-LOC

prepositions from, out of, etc.

FROM-POSS

preposition from