'HOW " / 0 R E S T R I C T A M B I G U I T Y 0 F D I B C O U R S E
B a r b a r a
D u n i n - K @ p l i c z
Institute
of
InformaticsU n i v e r s i t y
Of
W a r s a w P.O. B o x 1 2 1 0 0 0 - 9 0 1 W a r s z a w a , P O L A N DA B B T ~ C T
W e single out a c l a s s of p r o t o t y p e s i.e., a c l a s s of c o n s t r u c t i o n s forcing the obligatory c o r e f e r e n c e or obligatory n o n c o r e f e r e n c e . A n essential feature of p r o t o t y p e s is their undistinctiveness. In this s e n s e t h e y a r e the m o s t natural a n d efficient mearis of
c o m m u n i c a t i o n in d i s c o u r s e .
T h e non-application of p r o t o t y p e s h o u l d b e well motivated. T h i s l e a d s to the rule of r e s t r i c t e d c h o i c e s t a t i n g t h a t w h e n e v e r i t i s p o s s i b l e t h e a p p l i c a t i o n o f a p r o t o t y p e s h o u l d b e p r e f e r r e d .
T h e r u l e o f t h e r e s t r i c t e d c h o i c e s u g g e s t s t h e g e n e r a l o u t l i n e o f i n t e r p r e t i n g a m b i g u o u s s e n t e n c e s , s t r i c t l y s p e a k i n g , t h e m e t h o d o f o r d e r i n g a d m i s s i b l e i n t e r p r e t a t i o n s : t h o s e w h i c h c a n b e e q u i v a l e n t l y e x p r e s s e d b y m e a n s o f a p r o t o t y p e a r e l e s s p r o b a b l e . I n o t h e r w o r d s , t h e r u l e o f t h e r e s t r i c t e d c h o i c e c a n b e r e g a r d e d a s s o m e k i n d o f m e c h a n i s m o r d e r i n g t h e h y p o t h e s e s f o r c o m p u t e r / o n .
I N T R O D U C T I O N
T h e crucial p r o b l e m in d i s c o u r s e a n a l y s i s is the a p p r o p r i a t e transposition of all
e x p r e s s i o n s o c c u r r i n g in
it,
into reality (see, for instance, the f r a m e w o r k p r o v i d e d b y K e m pin
( K a m p , 1 9 8 1 ) ) . E v e np r e l i m i n a r y
a n a l y s i s s h o w s that o n e real object c a n b e identified b y v a r i o u s s u r f a c e constructions. T h i s f o r c e s the n e c e s s i t y of dividing s u r f a c e e x p r e s s i o n s into c l a s s e s d e n o t i n g i d e n t i c a l individuals.T h e a b o v e p r o b l e m c a n formally b e stated a s follows. T o e a c h d i s c o u r s e D w e a s s i g n s o m e reality w h i c h c a n b e u n d e r s t o o d a s a set ID of individuals ( s e m a n t i c d i s c o u r s e d o m a i n ) t o g e t h e r w i t h a s e t of r e l a t i o n s d e f i n e d on ID. T h e s e m a n t i c d i s c o u r s e domain c a n b e i n t e r p r e t e d t w o f o l d :
1.o a s a s e t of r e a l o b j e c t s i.e., o b j e c t s e x i s t i n g in a c t u a l w o r l d ;
2 ° a s a set of m e n t a l objects i.e., objects existing in l a n g u a g e u s e r ' s mind. A l t h o u g h t h e f i r s t i n t e r p r e t a t i o n i s m o r e n a t u r a l , it l e a d s t o s o m e o n t o l o g i c a l p r o b l e m s , c o n c e r n i n g t h e d i s t i n c t i o n o f f i c t i t i o u s a n d n o n - f i c t i t i o u s e n t i t i e s . S i n c e t h e r e i s n o s u c h d i s t i n c t i o n f r o m l i n g u i s t i c p e r s p e c t i v e t h e
s e c o n d i n t e r p r e t a t i o n s e e m s b e t t e r m o t i v a t e d . " / h e n e x t s t e p i s t o d e f i n e s y n t a c t i c d i s c o u r s e d o m a i n , d e n o t e d b y S _ , i . e . , a s e t
L) o f d i s c o u r s e e x p r e s s i o n s r e f e r r i n g t o
i n d i v i d u a l s ( s e t o f i n d i v i d u a l s ) . T h e m a p p i n g a s s i g n i n g i n d i v i d u a l s t o s y n t a c t i c e x p r e s s i o n s w i l l b e c a / l e d t h e r e f e r e n c e f u n c t i o n a n d d e n o t e d b y R. F ' o r m a / l y , R : S D 2 ID.
E x a m p l e
( D I ) J o h n a n d P e t e r a d m i r e winter. T h e y a r e o f t e n s k i i n g t o g e t h e r .
SDI" - {"John", "Peter", "winter", "they '''~
ID 1
- ~John, Peter, winter~( " J o h n " )
-
{John}
R
("Peter")-
{ P e t e r lR ( " t h e y " ) ,, { J o h n , P e t e r ] "
R ( " w i n t e r " )
- { w i n t e r }
W e s a y that d i s c o u r s e e x p r e s s i o n s x a n d y a.re coreferencial, w h a t w e d e n o t e b y x C y , if a n d o n l y if t h e y refer to the s a m e set of individuals.
Formally,
for e a c h x,y ~ S u x C y iff
R ( x ) =
R ( y )
It is readily verified that C is a ne q u i v a l e n c e relation. O b v i o u s l y e a c h
e q u i v a l e n c e c l a s s of C c o n t a i n s coreferentia/ e x p r e s s i o n s . T h e set of e q u i v a l e n c e c l a s s e s of C will b e ca/led the r e f e r e n c e sta~te of d i s c o u r s e a n d d e n o t e d b y R S D .
E x a m p l e
( D 2 ) J o h n took a knife.
( R S D 2 ) " J o h n 5~ ~"a "~ knife '~-.
( D 3 ) J o h n took a knife. H e hurt himself.
( R S D 3 )
~"JOhn:'," h e " , "himself'.~
knife"}.
r e f e r e n c e state. In this s e n s e R S D is a d y n a m i c notion Let u s n o t e also that the p r o b l e m of a n a p h o r a solution c a n b e r e g a r d e d a s defining the relation
C f o r
the w h o l e d i s c o u r s e .B o t h the s p e a k e r , w h i l e c o n s t r u c t i n ~ a d i s c o u r s e , and the hearer, while eunalysing it, t r y to a c h i e v e the i d e n t i t y of R S D a t e a c h step of the d i s c o u r s e . We a r g u e in t h i s p a p e r that to a c c o m p l i s h this effect, the
s p e a k e r has at his d i s p o s a l ( a t e a c h moment) a more r e s t r i c t e d set of l i n g u i s t i c
c o n s t r u c t i o n s t h a n it s e e m s intuitively. Let u s notice that e x p r e s s i o n s b e l o n g i n g to o n e e q u i v a l e n c e c l a s s h a v e v a r i o u s syntactic s h a p e s at different s t e p s of d i s c o u r s e . It ca/'* b e s h o w n that the syntactic f o r m of
e x p r e s s i o n s at particular m o m e n t s is not accidential, i.e., e l e m e n t s of indicated e q u i v a l e n c e c l a s s a r e not i n t e r c h a n g e a b l e .
P R O'I'O'I'YP E S
R e c e n t d i s c o u r s e theories p r o v i d e s e v e r a l levels of larlguage analysis: m o r p h o l o g i c a l , syntactic, s e m a n t i c a n d s o m e t i m e s pragmatic. E a c h of t h e s e levels d e t e r m i n e s a
characteristic set of notions a n d m e c h a n i s m s . It is a s s u m e d h e r e that the a n a l y s i s of 82", u t t e r a n c e o n e a c h levels of l a n g u a g e s h o u l d yield c o m p l e t e information obtainable b y tools available o n this l e v e l
C l a s s i c a l a n a p h o r r e s o l v e r s act o n
s e m a n t i c level o n d i s c o u r s e analysis. ~Are t a k e the position that for inflexion al l a n g u a g e s the c o r e f e r e n c e relation c a n b e partially d e s c r i b e d o n the syntactic l e v e l A n essential feature of this
p a r t i a l
c h a r a c t e r i s t i c is defining the c o r e f e r e n c e r e l a t i o n quite a p a r t from Peal i n d i v i d u a l s , i.e. w i t h o u t s p e c y f i n g the r e f e r e n c ef u n c t i o n .
"Po
fix s o m e i d e a s let u s c o n s i d e r a n utterance containing the n o u n p h r a s e s N P l , ...,N P
. If t h e r e i s n o i n f o r m a t i o n r e g a r d i n gn
c o r e f e r e n c e , a l l w e c a n d o i s t o a s s e r t t h a t t h e c o r e f e r e n c e r e l a t i o n i s i n c l u d e d b e t w e e n t h e " m i n i m a l " r e l a t i o n , i . e . , r e l a t i o n i d e n t i f i e d b y t h e u n i t e q u i v a l e n c e c l a s s e s N P ~ , ...,
NP a n d the mcLximal one, i.e. adm,Ring in
o n e nclass all n u m b e r - g e n d e r a g r e e a b l e p h r a s e s .
W e v e r y s e l d o m d e a l with s u c h a situation in practice. A l m o s t a / w a y s w e c a n a s s i g n to a n utterance a s y n t a c t i c level information stating obligatory- c o r e f e r e n c e or obliqatory n o n c o r e f e r e n c e of s o m e e x p r e s s i o n s .
T h e s u r f a c e c o n s t r u c t i o n s c a r r y i n g this kind of information with r e s p e c t to p r o n o u n s a n d z e r o p r o n o u n s (in the c a s e of elided subject) will b e called prototypes. Ln other w o r d s p r o t o t y p e s
c a n
b e r e g a r d e d a ssyntactic m e a n s forcing obligatory c o r e f e r e n c e or obligatory n o n c o r e f e r e n c e b e t w e e n p r o n o u n s or z e r o p r o n o u n s a n d other s u r f a c e
e x p r e s s i o n s .
Let u s c o n s i d e r
f e w
i n s t a n c e s ofp r o t o t y p e s . B e c a u s e the i d e a s p r e s e n t e d h e r e a r e i m p l e m e n t e d for the P o l i s h l a n g u a g e , the n o t i o n o f p r o t o t y p e w i l l b e i l l u s t r a t e d w i t h a n u m b e r of P o l i s h s e n t e n c e s . A n elided subject specific for inflexional l a n g u a g e s c a n b e o b s e r v e d here. It is clenoted b y (~
B e c a u s e elided subject e x p r e s s e s s o m e a s p e c t s of thematic continuity, its
i n t e r p r e t a t i o n s e e m s t o b e a n i m p o r t a n t s t e p d u r i n g d i s c o u r s e a n a l y s i s . E n g l i s h
t r a n s l a t i o n s o f p r e s e n t e d e x a m p l e s p r e s e r v e t h e i r s y n t a c t i c s h a p e . U n f o r t u n a t e l y t h e y a r e s o m e t i m e s incorrect a s E n g l i s h s e n t e n c e s .
(1.)
Piotr o b u d z i t si~1~)3..
podszec£~ d o o k n a ,~ 2 o t ~ v o r z y ~ j e
i ~)3 w y s k o c z y { .P e t e r w o k e up, ~ I c a m e to the w i n d o w , • 2 o p e n e d it a n d ~)3 j u m p e d out.
E x p r e s s i o n s :
Peter, #I, ~2, ~)3 a r e coreferentiaL A n o t h e r interpretation is u n a d m , s s i b l e , in (I) w e d e a l with obligatory c o r e f e r e n c e of e x p r e s s i o n s
( d e n o t e d b y a - -- b ) .
(2) ~ I ~ 2 podszeci% d o o k n a ,
4
~
4
~ s k o c z y ~
~)1. W o k e u p , q)2 c a m e to t h e w i n d o w ,
q)3 o p e n e d i t a n d # 4 j u m p e d o u t .
in (2), similarly a s in (a) (co-ordinate
c l a u s e s ) a n d in (3), (4) ( s u b o r d i n a t e c l a u s e s ) the o n l y a c c e p t a b l e interpretation is explicitely s h o w e d .
(3) Z~im C a , ~ s ~ e a ~ 2
z g a s i ~ ~wiat~o.
B e f o r e
911 left, 912 t u r n e d
t h e l i g h t off.
( 4 )
~].~_Z_gasi~ ~wiat~o, zanim....w~2 w y s z e d L
911 T u r n e d the L~ght off, b e f o r e ~ 2 left.
T h e n e x t e x a m p l e s c o n c e r n the obligatory n o n c o r e f e r e n c e of e x p r e s s i o n s ( d e n o t e d b y
a+-b)
(5) O n a lubi ja~
S h e likes her.
( 6 ) (~ z a p y t a ~ P i o t r a , ' ~ c z y
J a n p 6 j d z i e
d o t e a t r u .
( 7 ) ¢ U s i a d ~ d o stc~u, a .Tan naleuI: m u w i n a .
S a t a t t h e t a b l e , u n d J o h n p o u r e d him o u t s o m e w i n e .
T h e a b o v e e x a m p l e s p o s e t h e q u e s t i o n o f h o w t h e c l a s s o f p r o t o t y p e s s h o u l d b e s i n g l e d o u t . T h i s p r o b l e m c a n b e s o l v e d b y
s p e c i f y i n g a c o l l e c t i o n o f r u l e s c o n c e r n i n g t h e o b l i g a t o r y c o r e f e r e n c e a n d o b l i g a t o r y n o n c o r e f e r e n c e . T h e e x a c t f o r m a t o f t h e s e r u l e s i s b e y o n d t h e s c o p e o f t h i s p a p e r . F o r i n f l e x i o n a l l a n g u a g e s t h e y d e p e n d o n t h e t y p e of c o n s i d e r e d s e n t e n c e , t h e s e n t e n c e - - l e v e l f u n c t i o n s of c o n s i d e r e d p h r a s e s a n d t h e i r s y n t a c t i c s h a p e . A s a s i m p l e e x a m p l e of s u c h a r u l e l e t u s c o n s i d e r t h e b a s i c c r i t e r i o n of e x c l u d i n g c o r e f e r e n c e :
If t h e o b j e c t i s e x p r e s s e d b y m e a n s o f a r e f l e x i v e p r o n o u m , t h e n it i s c o r e f e r e n t i a l w i t h t h e s u b j e c t ; i n o t h e r c a s e s t h e
r e f e r e n t i a l i d e n t i l y o f t h e s u b j e c t a n d o b j e c t is e x c l u d e d .
T h i s criterion c a n b e a p p l i e d b o t h for deterrninig c o r e f e r e n t s of o b j e c t s - b l o c k i n g the subject, a n d in tesf/n~ the p o s s i b l e a n t e c e d e n t s of the s u b j e c t - b l o c k i n g the objects. T h i s is e x a c t l y the c a s e w e h a v e in
( 5 ) .
T H E R U L E OF' R E S T R I C T E D C H O I C E A c o n c l u s i v e criterion of b e i n g a p r o t o t y p e results from a n a l y s i n g a g i v e n s e n t e n c e it% isolation. If it is p o s s i b l e to a s s e r t o r to e x c l u d e the referential identity of s o m e
e x p r e s s i o n s of the s e n t e n c e , i n d e p e d e n t l y of its c o n t e x t t h e n the s e n t e n c e c a n b e r e g a r d e d a s a n i n s t a n c e of prototype. A n essential f e a t u r e of p r o t o t y p e s
is
t h a t t h e y a r ec o m p l e t e l y i n d i s t i n c t i v e a n d i n t h i s s e n s e t h e y a r e t h e m o s t p r o p e r t o o l f o r e x p r e s s i n g
a c e r t a i n r e l a t i o n s h i p i n t h e u t t e r a n c e . T h i s s t r o n g r e l a t i o n s h i p m a k e s it p o s s i b l e t o e l i m i n a t e s o m e i n t e r p r e t a t i o n s , w h i c h i n o t h e r c a s e s s h o u l d b e r e g a r d e d a s p r o b a b l e t o o .
If w e a g r e e t h a t a c h i e v i n g u n a m b i g u i t y o f d i s c o u r s e i s t h e m a j o r g o a l b o t h f o r t h e s p e a k e r a n d t h e h e a r e r , t h e n t h e n o n -
- a p p l i c a t i o n of prototype, a s the m o s t natural a n d efficient m e a / q s of c o m m u n i c a t i o n s h o u l d b e well motivated. W h e n s u c h a s p e c i a l r e a s o n is lacking, the s p e a k e r s h o u l d
a p p l y
aa prototype. U n d e r this a s s u m p t i o n the set of linguistic tools available to the s p e a k e r is restricted.
T h e notion of p r o t o t y p e c a n b e natural/y a p p l i e d o n the syntactic level of d i s c o u r s e a n a d y s i s to limit the n u m b e r of h y p o t h e s e s for further consideration. 13ut it c a n also b e useful o n the h i ~ h e r levels to interpret a m b i g u o u s d i s c o u r s e s . Strictly s p e a k i n ~ the p r o p e r t i e s of p r o t o t y p e s u g g e s t the g e n e r a l outline of i n t e r p r e t i n g a m b i g u o u s s e n t e n c e s , m o r e p r e c i s e l y a m e t h o d o f o r d e r i n ~ p o s s i b l e
i n t e r p r e t a t i o n s w i t h r e s p e c t t o t h e i r p l a u s i b i l i t y . F r o m t h e s e t of p o s s i b l e i n t e r p r e t a t i o n s o f a s e n t e n c e , t h o s e t h a t c a n b e e q u i v a l e n t l y e x p r e s s e d b y m e a n s o f p r o t o t y p e , s h o u l d b e r e g a r d e d a s l e s s plausible. T h e justification of this c h o i c e is clear: if the s p e a k e r w a n t e d to point out s u c h a n
interpretation,
h e w o u l d naturally a c h i e v e it b y a p p l y i n g a prototype.In v i e w of the o b o v e w e c a n formulate the rule of restricted c h o i c e . It states that w h e n e v e r i t is p o s s i b l e the application of a p r o t o t y p e s h o u l d b e p r e f e r r e d .
It i s i r r p o r t a n t t o n o t i c e t h a t t h e r u l e o f r e s t r i c t e d c h o i c e c a n b e v i e w e d f r o m t h e p e r s p e c t i v e b o t h o f t h e s p e a k e r c o n t r u c t i n g t h e d i s c o u r s e a n d t h e h e a r e r m o d e l l i n g it. T h e s p e a k e r s h o u l d a p p l y p r o t o t y p e s w h e n e v e r it is possible. T h e h e a r e r s h o u l d t a k e this fact into c o n s i d e r a t i o n .
Let us t r y to interpret the c o n c r e t e sentences with the help of the rule of restricted choice.
( 8 ) Zanim ~)I wyszed~, .Tan zgasi~ ~wiat{o.
Before ~ I leftmasc, .Tohn tumedmasc
the light off.
T h e r e a r e t w o interpretations here:
(9) Zanim
zgasi wia o
B e f o r e ~ I left, J o h n t u r n e d the light off. l
(1.0) Z a n i m ~ I w3zszed2, J a n zgasi{ ~wiat~o.
B e f o r e ~ l l left, J o h n t u r n e d the light off.
(~ d e n o t e s the r e f e r e n c e to the context).
B u t the first interpretation c a n b e e x p r e s s e d b y m e a n s of prototypes.
( P l ) Z a n i m ~ I ~Aryszed{, @ 2
zgasit
~wiat~o.B e f o r e ~ 1 left, ~ 2 t u r n e d the Light off.
A n o t h e r e x a m p l e i s m o r e c o m p l i c a t e d . ( 1 1 ) Z a n i m o__.nn w y s z e d ~ , ~ I zapy~ak ~eo,
c z y # 2 p6jdzie d o kina.
B e f o r e h e leftmasc , @I, h a d a s k e d him, w h e t h e r ~ 2 w o u l d h a v e g o n e to the c i n e m a .
In the e m b e d d e d c l a u s e
03. zapy%a~ gO
there acts the rule of obligatory n o n c o r e f e r e n c e e x c l u d i n g the referentia/ identily of s u b j e c t a n d o b j e c t in this s e n t e n c e :
Z a n i m o n w y s z e d ~ , @ ~ z a p y t a k j ~ o ,
c z y ~ 2 p6jdzie d o kina.
A c c o r d i n g to o u r definition the a b o v e s e n t e n c e is a n i n s t a n c e of a prototype.
E x c l u d i n g the c o r e f e r e n c e of p o i n t e d e x p r e s s i o n s d e c r e a s e s the n u m e r of p o s s i b l e interpretations, but d o e s not clear u p all referential relationships in this a m b i g u o u s s e n t e n c e . A l t h o u g h there a r e n o further syntactic p r e m i s e s to r e s o l v e this a m b i g u i t y w e c a n specify the less p r o b a b l e interpretation b y a p p y i n g the rule of restricted choice. If the s p e a k e r w a n t e d t o e x p r e s s the f o l l o w i n g
s e n s e :
( 1 2 ) Z a n i m X wyszeck%, X zapy%a.% go, c z y @1. p6jdzie d o kineu .
h e s h o u l d h a v e u s e d the following (structural) prototype:
(13) Z~im ¢
~
1
~ a p y t ~ g o ,c z y ~ 2 p 6 j d z i e d o k i n a .
( I n s u c h a s e q u e n c e o f c l a u s e s i n t h e s e n t e n c e the rule of o b l i g a t o r y c o r e f e r e n c e d e m a n d e s that ¢ a n d @1. s h o u / d b e identified).
It follows t h e r e f o r e that the interpretation: (3.4) Z a n i m o n w y s z e d k u . ~ l z a p vta~ go,
c z y ~ 2 p6jdzie d o kina.
is the less p r o b a b l e a n d s h o u l d b e c o m p u t e d a s the last one.
N O N M O N O T O N I C I T Y O F T H E R U L E 0 5 ' l q E S T R I C T E D C H O I C E
C o n s i d e r the following e x a m p l e :
( 1 5 ) I<iedy @I p o d s z e d ~ d o Piotra, by~ o n z d e n e r w o w a n y .
W h e n ¢ I c a m e n e a r Peter, h e w a s n e r v o u s .
T h e r e a r e t w o p o s s i b l e interpretations (3.6) K i e d y ¢ I p o d s z e d { d o Piofra, by~ o n
z d e n e r w o w a n y .
( 1,7 ) K i e d y
~ p . o d s z e d ~d o P i o t r a ,
by~A, o n
z d e n e r w o w a n y .
2 e c a u s e the s e c o n d interpretation c a n u n a m b i g u o u s l y b e e x p r e s s e d b y the prototypical c o n struction:
(3.8) K i e d y ~I p o d s z e d { d o Piotra, by~ ~)2 z d e n er%vowalny.
W h e n ~)I c a m e n e a r P e t e r Q 2 w a s n e r v o u s .
a c c o r d i n g to the rule of restricted c h o i c e the first interpretaf/on s h o u l d b e preferred.
T h e rule of resfx'icted c h o i c e is b a s e d o n the a s s u m p t / o n that w h e n e v e r it is p o s s i b l e p e o p l e u s e u n a m b i g u o u s constructions.
A l t h o u g h u s u a l l y va/id this a s s u m p t i o n c a n n o t b e r e g a r d e d a s g e n e r a @ truth. T h i s m e e u n s that the rule of restricted c h o i c e e n a b l e s o n e to j u m p to plausible but not ironclad c o n c l u s i o n s . "l~pically, s u c h c o n c l u s i o n s c a n b e invalidated w h e n n e w information i s available. In o u r e x a m p l e the p r e f e r r e d intezq0retation might h e o v e r t u r n e d w h e n w e e x t e n d o u r d i s c o u r s e a s follows:
(1.9) I<iedy ~ I p o d s z e d ~ d o Piotra, by~ o n zdener-vvowany.
B M ~ tc w y n i k w c z e ~ n i e j s z e j k~6tni z Piotrem.
¢ I c a m e n e a r P e t e r h e w a s W h e n
n e r v o u s .
T h a t
w a s the result of a n earlierT h e n e o e s s i t y
of
c h a n g i n g t h e p r e f e r r e d interpretation follcws f r o m the fact that n e w information is available. T h e p r o p e r t y of d r a w i n g plausible but defeasible i n f e r e n c e s c h a r a c t e r i z e s n o n - m o n o t o n i c r e a s o n i n g . V a r i o u s f o r m s of this kind of r e a s o n i n g a r e n o w b e i n g d e v e l o p e d ( s e e ( ~ A I - 8 4 ) ) .It is n o w w i d e l y r e c o g n i z e d that d i s c o u r s e u n d e r s t a n d i n g r e g u l r e s n o n m o n o t o n i c
m e c h a n i s m s i n m a n y a s p e c t s . T h e r u l e o f r e s t r i c t e d c h o i c e i s a n e x a m p l e o f s u c h a n o n m o n o t o n i c t o o l
C O N C L U S I O N S
(1.) W h i l e c o n s t r u c t i n g d i s c o u r s e t h e s p e a k e r w a n t s t h e h e a r e r t o u n d e r s t a n d h i m correctly. E v e n if h e u s e s a m b i g u o u s
c o n s t r u c t i o n s h e intends to cemrr, unicate the u n i q u e interpretations, a n d not to c r e a t e in h e a t e r ' s m i n d a set of a/l p o s s i b l e h y p o t h e s e s . It follows that c o n s t r u c t h a g N L U s y s t e m s , w h i c h ~ e n e r a t e all a d m i s s i b l e interpretations,
contradicts c o m m o n s e n s e r e a s o n l n ~ . S o the essential p r o b l e m is to d e t e r m i n e m e t h o d s o/ c h o o s i n g the m o s t a p p r o p r i a t e interpretation. If this plausible interpretation fails, i t s h o u l d b e revised.
( 2 )
E m p l o y i n g the rule o f restricted c h o i c e a s s u m e s the e x i s t e n c e of s o m e m e c h a n i s m w h i c h d e t e r m i n e s w h e t h e r a g i v e n c o n s t r u c t i o n c a n b e r e g a r d e d a s a prototype. 'l~bis c a n b e a c h i e v e d b y specifyins a set of rules quali~j'ing the o b U g a t o r y c o r e f e r e n c e a n d n o n c o r e f e r e n c e of referrins e x p r e s s i o n s . A partied set of s u c h rules for the l::ollsh l a n g u a g e h a s b e e np r e s e n t e d in ( D u n i n - K ~ p l i c z , 1 9 8 3 ) .
A C K N O W L E D G E M E N ' P
I w o u l d llke to t h a n k D r Witold L u k a s z e w i c z
for helping m e to clarify i d e a s p r e s e n t e d in this paper.
R E F E R E N C E S
D u n i n - K @ p l i c z B. ( 1 9 8 3 ) T o w a r d s better u n d e r s t a n d i n g of a n a p h o r a , in: P r e c . of t h e ist A C L C o n f e r e n c e , Piss, 1 3 9 - 1 4 4 . K a m p H. ( 1 9 8 1 ) A t h e o r y o f t r u t h a n d
s e m a n t i c r e p r e s e n t a t i o n , i n : 5 " o r m a l m e t h o d s i n t h e s t u d y o f l a n g u a g e , IV[athematisch C e n t r u m , A m s t e r d a m , 2 7 7 - 3 2 2 .
