EMASTERS

SCHOOL

Vincent Spincemaille

MAI-SLT

2002

A syntactic and semantic treatment of ergativity in a system network grammar

Vincent Spincemaille

EMASTERS

SCHOOL

Vincent Spincemaille

MAI-SLT

2002

The Company

• Language And Computing

• Zonnegem, Belgium

• 30 employees

•Focus: medical market

• Products: automatic text indexing, information retrieval, medical ontology

• www.landc.be

EMASTERS

SCHOOL

Vincent Spincemaille

MAI-SLT

2002

The Linguistics Department

• building a computational grammar for English to analyse medical abstracts/patient reports in order to improve information retrieval

• Goal: text understanding (so a correct grammatical AND conceptual analysis)

• Method: grammar formalism = Systemic-Functional Grammar (SFG)

• My task description: adjust the grammar to include correct parsing of ergativity (plus conceptual representation);

-mental verbs

-aspectual verbs

EMASTERS

SCHOOL

Vincent Spincemaille

MAI-SLT

2002

The Grammar Formalism

• System networks

• design of the grammar: features, AND-gates, OR-gates, realizations

lexical-verbintransitive-verb

monotransitive-verb

ditransitive-verbtransitive-verb

Compl: +1

Compl: {noun or {acc and pronoun}}

EMASTERS

SCHOOL

Vincent Spincemaille

MAI-SLT

2002

Dependency

.

[punctuation]

Head

examines

[verb]

Subj

doctor

[noun]

Deict

the

[determiner]

Obj

patient

[noun]

Deict

the

[determiner]

• dependency vs constituency

EMASTERS

SCHOOL

Vincent Spincemaille

MAI-SLT

2002

Linkbase

ICD-9-CM

LinkBase

1 million concepts350 LinkTypes

ICPC

SNOMED

3 million termsin different languages

Computer understandable

‘Meta’-entities

Language independent

• Concepts connected by Linktypes

EMASTERS

SCHOOL

Vincent Spincemaille

MAI-SLT

2002

• concepts, not lemma’s:

BIOPSY OF LIVER

IS-A: biopsy

HAS-SOURCE: liver

HAS-THEME: liver biopsy tissue

• linguistic descriptions of processes: material processes, being processes, etc.

Concept modeling in Linkbase

“The doctor that treated the patient now has Cancer”

MEDIC CANCERHas-HC-Phenom

MEDICAL-PROCEDURE

Has-Actor

Has-Actee PATIENT

EMASTERS

SCHOOL

Vincent Spincemaille

MAI-SLT

2002

Ergativity

• examples:

(1a) The bookkeeper killed his wife.

(1b) *His wife killed.

(2a) The doctor opened the valve.

(2b) The valve opened.

• How introduced into the grammar?

- list ergative verbs

- new category in lexicon: ergative verb

- new direct object: ErgObj

EMASTERS

SCHOOL

Vincent Spincemaille

MAI-SLT

2002

Ergativity(2)

• difference with normal transitive verbs:

-syntactically: limited

-main difference: semantically:

- characterization of ergativity in terms of different process-participant relations (Davidse 1999):

Transitive sentences: actor/goal

Ergative sentences: ergative-instigator/ergative medium

EMASTERS

SCHOOL

Vincent Spincemaille

MAI-SLT

2002

Ergativity (3)

INVESTIGATION-PROCESS

Actee (goal)

Actor

LINKBASE

Subject Transitive-verb

syntax Object

examines the patientThe doctor

EMASTERS

SCHOOL

Vincent Spincemaille

MAI-SLT

2002

IMPROVING-PROCESS

HAS-

ERGATIVE-

MEDIUM

HAS-ERGATIVE-

INSTIGATOR

LINKBASE

Subject Ergative-verb

syntax ErgObj

improves the patientThe doctor

Ergativity (4)

EMASTERS

SCHOOL

Vincent Spincemaille

MAI-SLT

2002

Ergativity (5)

IMPROVING-PROCESS

HAS-ERGATIVE-

MEDIUM

LINKBASE

Subject Ergative-verb

syntax

improvedThe patient

EMASTERS

SCHOOL

Vincent Spincemaille

MAI-SLT

2002

Conceptual definition of ergativity

• transitive verbs: material process:

criteria list:

has-actor

has-actee

• ergative verbs: ergative process:

criteria list:

has-instigator

has-medium

EMASTERS

SCHOOL

Vincent Spincemaille

MAI-SLT

2002

LINKBASE:ERGATIVE PROCESS

The doctor increased the pressure.

The pressure increased.

Het virus infecteerthet weefsel

La pression est augmentée.

Le docteur augmente la pression

Het weefsel infecteert.

SEMANTIC MAPPING

(language-dependent)

EMASTERS

SCHOOL

Vincent Spincemaille

MAI-SLT

2002

Conclusion

• Develop a system which handles ergativity in the grammar

• System network grammar: wide coverage, transparent grammar

• Practical use of theoretical linguistic research

• Further development: develop a semantic mapping component, add probabilistic parsing to reduce number of parses