Authorship

###### 1. Augusta Mela

Northern Paris Computer Science Lab (LIPN-CNRS)

###### 2. Christophe Fouqueré

Northern Paris Computer Science Lab (LIPN-CNRS)

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1. Introduction

Coordination has always been a centre of academic interest, be it in linguistic theory or in computational linguistics. The problem is that the assumption according to only the constituents of the

same category (1) may be conjoined is false; indeed, coordinations of different categories (2, 3)

and of more than one constituent (4, 5, 6, 7) shoud

not be dismissed as marginal.

(1) Jean danse la valse et le tango.

(Jean dances the waltz and the tango.)

(2) Je sais son âge et qu’elle est venue ici.

(I know her age and that she came here.)

(3) Un livre intéressant et que j’aurai du plaisir à lire.

(An interesting book and which I will enjoy to read.)

(4) Je demande à Pierre son vélo et à Marie sa canne à pêche.

(I ask Peter for his bike and Mary for her fishing rod.)

(5) Je demande à Pierre son vélo et à Marie d’où elle vient.

(I ask Peter for his bike and Mary where she comes

from.)

(6) Pierre vend un vélo et donne une canne à pêche à Marie.

(Peter sells a bike and gives a fishing rod to Mary.)

(7) Pierre a acheté un livre à Marie et un disque à Pierre pour

100F.

(Peter has bought a book for Mary and a CD for Peter

for 20 $.)

Consequently, this problem challenges the initial

choice of categories of description which is crucial

in the conception of the linguistic formalism. We

claim here that the constructive power of lexical

heads, encoded in the subcategorization feature,

explains the previous linguistic facts. In the coordinate structure, conjuncts may be of different

categories as well as of more than one constituent,

they just have to satisfy the subcategorization

constraints imposed by their functor if they are in

position of argument or to impose compatible

subcategorization constraints if they are functors,

where, as in Categorial Grammars (Dowty, 1988),

functors categories are those that bear unsatisfied

subcategorization requirements.

Our approach which is independent of any framework, is easily and precisely encoded in the formalism of Head Driven Phrase Structure Grammar (Pollard & Sag, 1994), which is based on

feature structures and makes available the feature

sharing mechanism we need.

The paper is organized as follows. Section 2 is a

brief account of previous approaches and section

3 is devoted to our approach. The french coordination with et serves throughout the paper as an

example.

2. Previous approaches

There exists a classical way to eschew the question

“what can be coordinated?” if one assumes a deletion analysis. Indeed, according to this approach

(Chomsky, 1957), (Banfield, 1981), only coordination of sentences are basic and other syntagmatic coordinations should be considered as coordinations of reduced sentences, the reduction being

performed by deleting repeated elements. This

approach comes up against insurmountable obstacles, chiefly with the technical difficulty of reversing the deletion process, in the analysis process

(Schachter, 1973), (Mela, 1992).

(Sag et al., 1985) have tried to make a direct

description of the conjoined expressions in reducing the constraint from requiring the same category for conjuncts to a weaker constraint of category compatibility. Technically, the compatibility

is checked by computing a “generalization” of

categories and imposing the generalization comprises all features expected in the given context.

For example, the context in (8), that is, the verb

être (to be), expects an predicative argument and

both categories NP and AP are just predicative

categories.

(8) Il est le père de Marie et fier de l’être . (NP + AP)

(He is Mary’s father and proud of it.)

However, this solution cannot be applied generally because all coordinations have not such “natural” intersection (cf.(2)). So we claim that we have

nothing else to do but explicitly enumerate, within

the head subcategorization feature, all the structures allowed as complement for a given lexical

head, that is, we will assume that the subcategorization feature has disjunctive values.

3. Our approach

Our proposal involves three stages. We begin by

formulating constraints on coordinate structures,

then we define how to build the coordinate structures and we end by specifying how the previous

constraints filter through such coordinate structures.

3.1. Constraints on coordinate structures

We distinguish the role of functor and that of

argument, where, as in Categorial Grammars,

functors categories are those that bear unsatisfied

subcategorization requirements. Lexical heads are

functors in relation to the arguments which they

select and, by composition, any expression that

contains an unsaturated functor is a functor (6)-(7)

and inherits the unsatisfied requirement from the

main functor. Arguments are the complements

selected by the head. As suggested by (Miller,

1991), adjuncts could be accorded the same status

as arguments by integrating them into the subcategorization requirement through an optional lexical rule. That would enable us to account for

coordination of adjuncts of different categories as

well as coordination of more than one constituent

with adjuncts.

In all cases, an argument may often be realized by

different categories. For example, the argument

required by savoir (to know) may be a NP or a

Completive: we say that the requirement is disjunctive and we represent the different alternatives

within subcategorization feature disjunctive values. When the lexical head requires several complements (to ask somebody something), the requirement is said to be a n-requirement. A

n-requirement is a multi-set of simple requirements. We claim then that :

(C1) A subcategorization 1-requirement is satisfied either by one of the disjuncts or by a coordination of disjuncts.

(C2) A subcategorization n-requirement is satisfied by m arguments, 0 <m < n, either by a sequence of m arguments such that each argument satisfies one and only one element of the requirement

or by a coordination of such sequences. The result

has a n-m requirement.

Note that (C1) and (C2) should be computed simultaneously in order to account for structures as (4).

The notion of partial saturation in (C2) allows us

to account for coordination of sub-series of arguments as in (5). As an entity can be both functor

and argument (1), our coordination criterion (necessary condition) is the following one :

The conjuncts must satisfy the same simple or

multiple subcategorization requirement and impose compatible subcategorization requirements.

In order to compute this compatibility, we define

u+

,an extension of the feature structure unification

to disjunctive and set values.

3.2. How coordinate structures are built

As in (Cooper, 1991), if son âge is a NP and

qu’elle est venue ici is a Completive, son âge et

qu’elle est venue ici is a conjunctive composite

categorie NP ^ Compl. We extend the operation

“^” to complex categories and we use a new connector in order to represent the expressions of

more than one constituent within a tuple. With

these two connectors, < > in order to represent the

expressions of more than one constituent within a

tuple. With these two connectors, a total structuring of complements is possible and all coordinate

structures may have a status. Nevertheless, the

extension to complex categories is not uniform:

coordinate structure features are not necessarily

composites or tuples of corresponding features

from each conjunct. In fact, features which are

allowed to have conflicting values are compounded, whereas other features as Subcat must unify.

This structuring is encoded within the following

HPSG-like lexical entry of et:

Phon \ et \

Synsem < [1], . . M < [1' ], . . M'

Part < C ,..,C > < C' ,..,C' >

Subcat

[1]

Part C

Subcat {} ,.. M

Part C

Subcat

[1' ]

Part C'

Subcat {} ,.. M'

Part C'

Subcat

1M 1 M

1 M

M

1 M

M

M + M

,[ ] ,[ ]

,[ ]

,[ ] >∧ >

∧

| Cat

Φ

Φ

Φ Φ

'

u '

203

The following LP-constraint on the lexical entry

of et ensures the correct order between conjunction and conjuncts :

[1] < ..< [M] < conj < [1’] < .. < [M’].

The coordination of m-tuples, as well as the coordination of simple conjuncts (M=1) stems from

the saturation of the conjunction et. As required by

linguistic facts, only the last element of the tuple

CM (or C’M) can be unsaturated and be the source

of inheritance.

3.3. Saturation schemata

It remains now to say how a general structured

complement satisfies a general requirement, that

is to say, where the checking of the conditions C1

and C2 is activated. They are called from a saturation schemata which is intended to replace the

HPSG Subcategorization Principle. This saturation schemata allows either a partial (Ψ ≠ {}) or

total saturation (Ψ = {}) by saturated complements

(Ψ’ = {}), or total saturation (Ψ = {}) by complements, the latter being partially (Ψ’ ≠ {}) or totally

saturated (Ψ’ = {}) :

where Σ satisfies Φ

and Φ is a m-requirement, Ψ n-m requirement, Σ

a general structured complement, Ψ or Ψ’ is empty.

3.4. Example of analysis

Example of resulting HPSG-like analysis is given

in figure 1 for the underlined phrase in (9):

(9) Jean conseille à son père d’acheter et à sa mère d’utilis

er un lave-vaisselle.

(Jean advises his father to buy and his mother to use a

dish washer.)

4. CONCLUSION

This approach based on concept of functor, argument and subcategorization allows us to account

for many coordination datas.

Its formalization comprises two parts which are

conceptually independants. On one hand, we have

extended the feature structure unification to disFigure 1. Analysis of conseille à son père d’acheter et à sa mère d’utiliser un lave-vaisselle

204

junctive and set values in order to check the compatibility and the satisfiability of subcategorization requirements by structured complements. On

the other hand, we have considered the conjunction et as the head of the coordinate structure,

so that coordinate structures stem simply from the

subcategorization specifications of et and the general schemata of the head saturation.

Both parts have been encoded within HPSG using

the same resource that is the subcategorization and

its principle which we have just extended to account for our disjunctive values of requirements

and structured categories.

Bibliography

Cooper, R. P. 1991. Coordination in unificationbased grammars. Actes 29° ACL, 167–172.

Mela, A. 1992.Traitement automatique de la coordination par “et”. Thèse de l’université de Paris

XIII, Villetaneuse (F).

Mela, A. et Fouqueré, C. 1994. “A coordination

criterion based on multiple and disjunctive

subcategorization”, dans The Proceeding of

the 1994 Kyoto Conference, Akira Ishikawa

et Yoshihito Nitta (éds), Société Logico-Linguistique du Japon, Tokyo, Japon, 31–40.

Mela, A. et Fouqueré, C.1996. “Coordination as a

direct process”. Actes 34° ACL, Santa Cruz. (to

appear).

Miller, P. 1991. Clitics and Constituents in Phrase

Structure Grammar. Garland (eds), New York.

1992.

Paritong, M. 1992. Constituent Coordination in

HPSG. KONVENS, Springer Verlag, Berlin,

228–237.

Pollard, C. et Sag I.A. 1994. Head-Driven Phrase

Structure Grammar. Chicago : UCP and Stanford: CSLI Publications.

Sag I., Gazdar G., Wasow T., Weisler S. 1985.

Coordination and how to distinguish categories. Natural Language and Linguistic theory,

n°3, 117–171.

Schachter, P. 1973: “Conjunction”, The Major

structures of English, Chap 6. Holt, Rinehart

& Winston. USA.

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Conference Info

In review

Hosted at University of Bergen

Bergen, Norway

June 25, 1996 - June 29, 1996

147 works by 190 authors indexed

Scott Weingart has print abstract book that needs to be scanned; certain abstracts also available on dh-abstracts github page. (https://github.com/ADHO/dh-abstracts/tree/master/data)

Conference website: https://web.archive.org/web/19990224202037/www.hd.uib.no/allc-ach96.html

Tags

**Keywords:**disjunction linguistic formalism subcategorization**Language:**English**Topics:**None