Pragmatic sensitivity in NL interfaces and the structure of conversation

P r a g m a t i c s e n s i t i v i t y in N L i n t e r f a c e s a n d the s t r u c t u r e of c o n v e r s a t i o n

T o m W a c h t e l

S c i c o n Ltd, L o n d o n a n d

R e s e a r c h U n i t for I n f o r m a t i o n S c i e n c e & AI, H a m b u r g U n i v e r s i t y

i . I n t r o d u c t i o n

The work r e p o r t e d here i s being conducted as p a r t o f t h e L O K I p r o j e c t (ESPRIT P r o j e c t I 0 7 , "A l e g i o o r i e n t e d approach t o knowledge and d a t a bases s u p p o r t i n g n a t u r a l user i n t e r a c t i o n " ) . The goal o f t h e NL p a r t of t h e p r o j e c t i s t o b u i l d a p r a g m a t i c a l l y s e n s i t i v e n a t u r a l language i n t e r f a c e t o a

knowledge base. By " p r a g m a t i c a l l y

s e n s i t i v e " , we mean t h a t t h e system should n o t o n l y produce w e l l - f o r m e d c o h e r e n t and c o h e s i v e language (a minimum r e q u i r e m e n t of any NL system designed t o handle d i s c o u r s e ) , but should a l s o be s e n s i t i v e t o t h o s e a s p e c t s o~ user b e h a v i o u r t h a t humans are s e n s i t i v e %o o v e r and above s i m p l y p r o v i d i n g a good r e s p o n s e , i n c l u d i n g producing o u t p u t t h a t i s a p p r o p r i a t e l y d e c o r a t e d w i t h t h o s e minor and s e m a n t i c a l l y i n c o n s e q u e n t i a l

elements o f language t h a t make the

d i f f e r e n c e between n a t u r a l language and n a t u r a l n a t u r a l language.

This paper c o n c e n t r a t e s on the

r e p r e s e n t a t i o n o f t h e s t r u c t u r e of c o n v e r s a t i o n i n our system. We w i l l f i r s t o u t l i n e ~he r e p r e s e n t a t i o n we use f o r d i a l o g u e moves, and then o u t l i n e t h e n a t u r e o f t h e d e f i n i t i o n o f w e l l - f o r m e d d i a l o g u e t h a t we a r e o p e r a t i n g w i t h . F i n a l l y , we w i l l n o t e a few e x t e n s i o n s t o t h e r e p r e s e n t a t i o n mechanism.

2. The HOVE f r a m e

We a r e assuming a s e v e n - s l o t f r a m e f o r t h e r e p r e s e n t a t i o n o f m o v e s w i t h i n a d i a l o g u e , w i t h t h e f o l l o w i n g s l o t s : HOVE, USER, AGENT,

TURN, ACT~ B A S E , CONT. Every m o v e i n a

c o n v e r s a t i o n i s r e p r e s e n t e d by such a f r a m e . The H O V E s l o t u n i q u e l y i d e n i t i f i e s a p a r t i c u l a r move i n t h e c o n v e r s a t i o n by an a r b i t r a r y i n t e g e r . The USER s l o t i d e n t i f i e s t h e o u c r e n t user o f t h e system. The AGENT s l o t s p e c i f i e s whether i t i ~ a u s e r move o~' a system move. The TURN s l o t has t h e v a l u e OPEN n o r CLOSE n, where n i s a number t h a t r e f e r s t o a p a r t i c u l a r exchange. T y p i c a l l y , a move w i t h a v a l u e OPEN n f o r t h e TURN s l o t might be a r e q u e s t , and one w i t h a CLOSE n v a l u e t h e c~orresponding r e s p o n s e .

The ACT s l o t s p e c i f i e s what a c t i s performed by t h e u t t e r a n c e . This w i l l be e i t h e r a speech a c t , o r t h e v a l u e ACTION, s i n c e n o t

a l l moves need be speech a c t s . The range of

speech a c t s t h a t t h e system w i l l have t o r e o o g n i s e or' produce i s c l e a r l y s m a l l e r than t h a t which o c c u r s i n c o n v e r s a t i o n s between humans. F u r t h e r m o r e , c e r t a i n speech a c t s w i l l be o f p r i m a r y i m p o r t a n c e g i v e n t h e domain o f a p p l i c a t i o n o f t h e system, namely, as a f r o n t end t o an e x p e r t system. We have t h e r e f o r e produced an i n i t i a l h i e r a r c h y o f

p o t e n t i a l l y r e l e v a n t speech a c t s

(Waehtel 1985a), where t h e major

c l a s s i f i c a t i o n i s i n t o r e q u e s t s , a s s e r t i o n s and commentaries. Some o f t h e s e are r e f e r r e d t o below. M a n y o f t h e speech a c t s we use go one l e v e l below what i s t r a d i t i o n a l l y viewed as a speech a c t ( i . e . i n t h e sense o f A u s t i n (~952), S e a r l e ( 1 9 6 9 ) , e t c . ) and may be compared w i t h d i s t i n c t i o n s t h a t McKeown (1985: 9 f f . ) , f o r example, d i s c u s s e s under t h e c a t e g o r y o f " r h e t o r i c a l p r e d i c a t e s " , though t h e y are by no means t h e s a m e . The

o n l y speech a c t s d i s c u s s e d below a~e

r e f e r r e d t o by t h e f o l l o w i n g a b b r e v i a t i o n s :

R E Q A C T

r e q u e s t - f o r - a c t i o n

R E Q A F F r e q u e s t - f o r - a f f i p m a t i o n S U P P A F F s u p p l y - o f - a f f i r m a t i o n REQCONST r e q u e s t - f o r - c o n s t a n t SUPPCONST s u p p l y - o f - c o n s t a n t

R E Q C O N F

r e q u e s t - f o r - c o n f i r m a t i o n SUPPCONF s u p p l y - o f - c o n f i r m a t i o n The BASE s l o t s p e c i f i e s t h e c u r r e n t t o p i c , i n t h e v e r y r e s t r i c t e d sense c f a p o i n t e r t o

t h e node i n t h e ~emantic network t h a t

c o r r e s p o n d s t o t h e o b j e c t what t h e c u r r e n t exchange i s a b o u t . This s i m p l i s t i c v i e w o f t o p i c i s adopted here as a f i r s t s t e p o n l y , and s e r v e s t o i ~ l u s t r a t e t h e p o i n t s d i s c u s s e d below.

" l o c a l c o h e r e n c e " i n t h e sense o f Hobbs (1982: 227) a r e a l s o r e l e v a n t h e r e . The p a r t i c u l a r i l l o o u t i o n a r y f o r c e o f an u t t e r a n c e w i l l be a f u n c t i o n o f t h e v a l u e o f t h e ACT s l o t and t h e CONT s l o t . S u b d i a l o g u e s t h a t are n o t i n t h e mainstream o f t h e c o n v e r s a t i o n w i l l be i d e n t i f i e d by p a r t i c u l a r r e l a t i o n s h i p o f v a l u e s f o r t h e TURN s l o t between a d j a c e n t moves, enhanced by t h e v a l u e s o f t h e ACT s l o t s f o r t h e

m o v e s .

Some examples o f t h e use o f t h i s frame t o r e p r e s e n t s e q u e n c e s of u t t e r a n c e s in c o n v e r s a t i o n s c a n be f o u n d in W a o h t e l

(1985b, 1985o), i n c l u d i n g i t s use t o

i d e n t i f y s h i f t s o f t o p i c , s u b d i a l o g u e s and r e l e v a n c e , as w e l l as t h e c o n t e x t u a l d i s a m b i g u a t i o n of s p e e c h a c t s , w h i c h is t h e m a i n t o p i c of t h e s e w o r k i n g p a p e r s .

3. T h e s t r u c t u r e of c o n v e r s a t i o n

We assume t h a t i t i s p o s s i b l e t o d e f i n e t h e s t r u c t u r e o f a p o s s i b l e c o n v e r s a t i o n by r u l e . A c t u a l human-human c o n v e r s a t i o n s may d e f y such a n a l y s i s , as i l l u s t r a t e d by, f o r e x a m p l e , t h e w o r k of S a c h s , S c h e g l o f f & J e f f e r s o n (1974). However, t h e p o s s i b l e ways i n which t h e c o n v e r s a t i o n s we a r e d e a l i n g w i t h may go are s e v e r e l y l i m i t e d by t h r e e f a c t o r s : (a) t h i s i s an i n t e r f a c e t o an e x p e r t system ( o r some s i m i l a r l y s p e c i f i c s o f t w a r e ) , which d e l i m i t s t h e p o s s i b l e range o f t o p i c s ; (b) one of t h e p a r t i c i p a n t s i n t h e d i a l o g u e i s a machine, which means t h a t i t w i l l n o t suddenly want t o i n d i c a t e t h a t , f o r e x a m p l e , A l b e r t ' s n i e c e is a f r i e n d f r o m s c h o o l , b u t t h i s f a c t h a s no b e a r i n g o n t h e s u p p o r t i v e t h i n g s b e i n g s a i d a b o u t h e r ; a n d (o) t h e o t h e r p a r t i c i p a n t k n o w s t h a t h i s i n t e r l o c u t o r i s a machine, and w i l l behave a c c o r d i n g l y . T h e r e f o r e , w h a t we n e e d to m o d e l is n o t a t y p i c a l l y n a t u r a l o p e n h u m a n c o n v e r s a t i o n , b u t a r e s t r i c t e d t y p e o f c o n v e r s a t i o n t h a t a l s o o c c u r s between humans i n c e r t a i n w e l l - c i r c u m s c r i b e d c o n t e x t s . For example, a c o n v e r s a t i o n between a would-be passenger and a t i c k e t c l e r k a t a r a i l w a y s t a t i o n i s c l o s e r t o what we n e e d t o model, and i n such oases i t i s p o s s i b l e t o d e f i n e w h a t is or is n o t a w e l l - f o r m e d c o n v e r s a t i o n by r u l e s of an a b s t r a c t n a t u r e t h a t may w e l l be i n a d e q u a t e f o r o t h e r n a t u r a l l y o c c u r r i n g c o n v e r a t i o n s .

We t h e r e f o r e propose t h r e e r u l e s t h a t d e f i n e t h e n o t i o n o f w e l l - f o r m e d c o n v e r s a t i o n i n t h e p r e s e n t c o n t e x t , making t h e f o l l o w i n g a s s u m p t i o n s . The s t r u c t u r e o f a c o n v e r s a t i o n can be r e p r e s e n t e d as a t r e e s t r u c t u r e . The w e l l f o r m e d n e s s o f such t r e e s can be d e f i n e d by r e w r i t e r u l e s . The maximal number o f l e v e l s o f embedding i n such t r e e s i s s i x (see b e l o w ) . I n p a r t i c u l a r , s u b d i a l o g u e s can be embedded w i t h i n d i a l o g u e s , but t h e r e can be no embedding w i t h i n s u b d i a l o g u e s . The l a s t r e s t r i c t i o n c o n f l i c t s w i t h what people do. It i s one o f t h e r e s t r i c t i o n s we c o n s i d e r n e c e s s a r y , and which can be handled i n such a way t h a t t h e user w i l l n o t n o t i c e

36

t h a t any such r e s t r i c t i o n e x i s t s .

We assume t h a t t h e f o l l o w i n g f o u r c a t e g o r i e s are s u f f i c i e n t f o r t h e r e p r e s e n t a t i o n o f t h e s t r u c t u r e o f c o n v e r s a t i o n . The symbols used s e r v e as mnemonics f o r t h e i r a p p r o x i m a t e c o u n t e r p a r t s i n E n g l i s h , but t h e y should n o t b e s t r i c t l y equated w i t h them: CONV ( c o n v e r s a t i o n ) , DIAL ( d i a l o g u e ) , EXCH (exchange) and MOVE (as d i s c u s s e d a b o v e ) . To f o r m u l a t e i n i n f o r m a l terms t h e g e n e r a l s t y l e and atmosphere o f t h e r u l e s t h a t we w i l l propose more f o r m a l l y below, l e t us say t h a t a CONV may c o n s i s t o f one o r more DIALs, a DIAL may c o n s i s t o f one o r more

EXCHs, and an EXCH c o n s i s t s o f two MOVEs,

w i t h each o f t h e s e MOVEs f o l l o w e d by an o p t i o n a l DIAL.

A major p o i n t about c o n v e r s a t i o n s t h a t must be handled i n a grammar o f t h i s t y p e i s t h e f a c t t h a t a l t h o u g h MOVEs a r e t h e o n l y t e r m i n a l nodes, and are t h e r e f o r e t h e nodes t h a t c o r r e s p o n d t o t h e u t t e r a n c e s t h a t are a c t u a l l y produced, w i t h a l l o t h e r nodes r e p r e s e n t i n g more a b s t r a c t e l e m e n t s , c e r t a i n f e a t u r e s o f c o n v e r s a t i o n n e e d t o be a s s o c i a t e d w i t h t h e s e a b s t r a c t nodes. For example, a l t h o u g h each MOVE i s s p e c i f i e d f o r who t h e c u r r e n t user o f t h e system i s and each MOVE a l s o has a p a r t i c u l a r t o p i c , as d i s c u s s e d above, t h e s e n o t i o n s p r o p e r l y

belong t o more a b s t r a c t l e v e l s of

c o n v e r s a t i o n a l s t r u c t u r e . Who t h e u s e r i s can be d e f i n e d a t t h e CONV l e v e l ( i . e . we d e f i n e a CONV as a c o n v e r s a t i o n w i t h one u s e r ) . The t o p i c of an u t t e r a n c e can be d e f i n e d a t t h e DIAL l e v e l ( i . e . a CONV can c o n s i s t o f one o r more d i a l o g u e s , each on a s i n g l e t o p i c ) . F u r t h e r m o r e , a DIAL can c o n s i s t o f one o r m o r e EXCHs, and i t i s a t t h i s p o i n t t h a t t h e c o n t e n t o f t h e u t t e r a n c e s t h a t form p a r t o f t h a t EXCH i s d e f i n e d .

L e t us now be more p r e c i s e . We a s s u m e t h a t some o f t h e s l o t s mentioned above i n t h e MOVE frame a r e r e p r e s e n t e d as f e a t u r e s on t h e nodes i n t h e t r e e s r e p r e s e n t i n g t h e s t r u c t u r e o f t h e c o n v e r s a t i o n o f which t h e moves d e s c r i b e d by t h e MOVE frames a r e p a r t . This a s s o c i a t i o n o f f e a t u r e s w i t h nodes, p l u s t h e assumption t h a t a l l f e a t u r e s t r i c k l e down, w i t h a few e x c e p t i o n s d i s c u s s e d below, p r o v i d e s f o r t r e e s o f t h e g e n e r a l form shown i n Table i . The l o w e r case l e t t e r s a r e c o n s t a n t s . Note t h a t t h e v a l u e s o f t h e B A S E f e a t u r e on t h e s u b d i a l o g u e nodes have n o t been s p e c i f i e d . We r e t u r n t o t h i s p o i n t below. Table I r e p r e s e n t s a g o a l : t h e s o r t o f s t r u c t u r e s we want t h e r u l e s t o produce. The f o l l o w i n g t h r e e r u l e s g e n e r a t e t r e e s o f t h i s t y p e . Kleene Plus n o t a t i o n i s used.

M O V E

F:il

A S E : b O N T :

U R N : T a b l e I

I

D IAL

ASlE:_J

I EXCIt

S E ~

it]

A S E

[

[ D I A L B SER

E X C H A S E :b ON~ :

C O N V

1 E X C H A S E : ] O N e : ,~1 ]

MOVE MOVE MOVE MOVE

a s E : l

I nAsE:

I n a s E :

I BASE: l

I ~ A S E : I I BASE

O~T:S I ICOm~:

ICO~'r:

ICOm'-m I ICOm~:q ICOm'

r D I A L A ~ E :

E X C H

~

s ~ . . ~]

ASE : |

kCO~r :

nS

MOVE MOVE HOVE

[BASE : [CONT: [~URN :

D I A L UBSER :

AsIE:

~

EXCIt

SER:iN ASH : ONLY:

F . . .

MOVE MOVE

ASE:Pl

pASE:

o~T.~ I Ices,:

[TURN:o_] [jUURN:

C O N V

3

E X C } ~

B A S E : ~

/

co~T:~ /

2

-~

DJ:AI.,d+

DI~L d

.--)

EXCHj L

ABE : b [ p a s s : BASl!: :?[

~ D : -

]

~u~D :

suBD: r I

_ . ~ o m : o d

-->

M O V E

n[ B A S E : ~ | ICON'.e: 6 |

[~ul~N : O e E ~ J

< ( D I A L d ) > M O V E n ( ( D I A L d d I)

[~URN : CLOSI?

f e a t u r e v a l u e s t r i o k l e down i n t h e r i g h t oases. Node s u b s o r i p t s d i s t i n g u i s h between d i f f e r e n t i n s t a n o e ~ o f t h e same node. Note

t h a t Greek l e t t e r s are a l s o used a~

v a r i a b l e s f o r node s u b s o r i p t s ( r u l e ( 3 ) ) . Round b r a o k e t ~ i n d i o a ~ e o p t i o n a l i t y i n the usual way. Angle b r a o k e t s ( r u l e ( 3 ) ) are u s e d in t h e s a m e w a y as u s e d by e . g . L a b o r

(1972: oh. 8) i n t h e s t u d y o f

~ o o i o l i n g u i s t i o v a r i a t i o n . They i n d i o a t e a r e l a t i o n s h i p between elements on the l e f t and on t h e r i g h t o f t h e r u l e . The e x p a n s i o n on t h e ~ i g h t i s o n l y p o s s i b l e i f t h e f e a t u r e on t h e l ~ ! f t o f t h e r u l e has t h e v a l u e s p e o i f i e d , i f both a r e enalosed i n a n g l e b r a c k e t s . I n t h e p r e s e n t ease, t h e y a r e used t o p r e v e n t t h e e x p a n s i o n ~f a s u b d i a l e g u e as a f u r t h e r s u b d i a l o g u e . The f e a t u r e ESUBD=-3

i s i n t r o d u o e d by t h e r u l e t h a t expands CONV.

The r u l e e;¢panding DIAL o o p i e s t h i s f e a t u r e w i t h t h i s v a l u e . The r u l e expanding EXCH a l l o w s an expansion o f EXCH tQ i n c l u d e

( o p t i o n a l l y ) one o r two DIALs, but i f t h e DIALs appear, then t h e y o a r r y t h e f e a t u r e [SUBD:+]. The e x p a n s i o n o f such a DIAL by r u l e (2) o o p i e s t h i s f e a t u r e w i t h t h i s v a l u e , as b e f o r e , when t h e DIAL i s expanded t o one o r more EXCHs. However, s i n o e t h e E X C H s so generat, ed o a r r y t h e f e a t u r e [GUBD:+3, t h e r u l e t h a t expands EXCH w i l l n o t a l l o w t h e p o s s i b i l i t y of f u r t h e r DIALs, beoause any suoh e~pansion i s o o n d i t i o n a l upon t h e EXCH h a v i n g t h e f e a t u r e [SUBD:-3, as s p e o i f i e d i n r u l e ( 3 ) .

Table 2

'

I

MOVE I

]

SER: Max

|

I~

SE: IJCAI |

~ S E R : Max

NT: CI

|

IBASE: EXCH

RN: OPEN I

~ U B D : +

ENT:USER

|

I

T:

REQCONST~

I

EXCH 2

'

[image:4.612.82.565.103.723.2]

~ S E R : Max q

|SUBD:

LC_0NT: C2 _ J

/___

f

]

MOVE 2

OVE: 2

SER: Max

ASE: EXCH I

ONT: C2

URN: OPEN 2

GENT:SYSTEM

T ~ Q C O N ~

CONV I

~SER: Max~

f

DIAL I

]

ASE :

IJCA_~

UBD :

-

f

EXCH I

FSE~: Max q

IBASE : IJCAI I

ISUBD :

CmONT: cI 3

l

J

MOVE 6

I O V E : 6

q

SER: Max

|

DIAL3

ASE: IJCAI

|

~ S E R : Max ]

ONT: CI

|

IBASE: EXCH

URN: CLOSE I |

~SUBD: +

GENT:SYSTEM

|

I

CT : SUPPCONST~

J

EXCH3

I

EXCH4

FsER:

Max

-1

r - ~

FSER,

Mox

]

IBASE: E x c e l I

[ s 3 )

lEASE: EXCH

|suED: +

/

" ~

Isu sD: +

~ONT [ c 3

__1 ...

LC0NT i C4

I I I I

__ __ MOVE 3

__ __ MOVE 4

_ __ MOVE 5

__ M O V E

7

__ __ MOVE 8

u s s a : Max

I USER: Max

lUSER: Max

//USER: Max

] / U S ~ R : Max

|

BASE: EXCH

1

I BASE: EXCU 1

lEASE: EXCH 1

/ / B A S E : EXCH ~ / / E A S E : EXCH

1 |

CONT: C2

I CONT: C3

/CONT: C3

//CONT: C4

'

TURN: CSOSE 2 / TURN: OPEN 3

/TURN: CLOSE 3

/ /TURN: OPEN 4 / /c°NT:

/

C4

/

/TURN: CLOSE 4 /

/AGENT:USER

/ IAGENT:SYSTEM

/AGENT: USER

/ F GENT:usER

/ / AGENT=SYSTEM /

v a r i a b l e . The same c o n s t a n t i s used as t h e v a l u e o f t h e f e a t u r e BASE i n s u b d i a l o g u e s . What t h i s amounts t o i s a s t i p u l a t i o n t h a t t h e t o p i c o f a s u b d i a l o g u e i s t h e EXCH t h a t i t i s p a r t o f , which seems t o be a b o u t r i g h t i n t u i t i v e l y . T h i s i s what m a k e s them m e t a l i n g u i s t i o i n c h a r a c t e r . F u r t h e r m o r e ,

n o t e t h a t t h i s i s a case where a

f e a t u r e / v a l u e p a i r does n o t t r i c k l e down. T h i s i s t a n t a m o u n t t o s t i p u l a t i n g t h a t DIAL

i s a BASE-bounding node: i t c r e a t e s

" i s l a n d s " w i t h B A S E s t h a t do n o t e x t e n d upwards t o t h e main d i a l o g u e , b u t w i t h o u t o v e r w r i t i n g t h e BASE of t h e c u r r e n t main d i a l o g u e . A g a i n , t h i s s e e m s i n t u i t i v e l y c o r r e c t .

L e t us now p r o v i d e a c o n c r e t e example o f t h e s t r u c t u r e t h a t t h e s e r u l e s a s s i g n t o a d i a l o g u e such as ( 4 ) .

38

4 Ui When i s t h e n e x t J I C A I m e e t i n g ? Si I presume you mean " I J C A I "

U2 Yes

B2 Do you mean t h e n e x t c o n f e r e n c e o r t h e n e x t c o n v e n e r s ' meeting?

U3 Conference

$3 12 August

U4 19857

$4 Yes

over t h e f a c t t h a t t h e BASE could not be i d e n t i f i e d i m m e d i a t e l y , which i s what t r i g g e e e d t h e s u b d i a l o g u e s . We add, h o w e v e r , n e e t a i n f e a t u r e s t h a t w e c e d i s c u s s e d e a r l i e e , s u c h a s M O V E , A G E N T a n d ACT, t o o l a e i f y h o w t h e f i n a l f o c m of t h e f r a m e e e p r e s e n t i n g e a c h M O V E is d e e i v e d .

T h i s i s a o o n v e e s a t i o n i n w h i c h t h e r e is o n l y oFie m a i n d i a l o g u e arid o n l y o n e m a i d e x c h a n g e w i t h i n t h a t d i a l o g u e . I h o p e t h a t it is c l e a r h o w t h e s e a d d i t i o n a l e l e m e n t s w o u l d b e i n c o e p o r a t e d i n t o t h e s t r u c t u r e , a n d h o w t h e a p p r o p r i a t e v a l u e s f o c B A S E , CON? and SUBD w o u l d be i a a i n t a i n e d o r c h a n g e d .

I t i s i n t e e e s t i n g t o n o t e t h a t t h e n o d e s iri c o n v e e s a t i o n t r e e s of t h i s s e c t h a v e a c o n c e p t u a l v a l i d i t y l i n t h a t d J . ~ f e c e e t n o d e t y p e s (Jo~'eespond t o d i f f e e e n t a s p e c t s of a ~ e n v e ~ ° s a t i e r i o T h u s a C O N Y n o d e e o c ~ ' e s p o n d s t o " t h i s (Iollve~'sation w i t h t h i s u s e c " , a D I A L [:SUBD : - 3 n o d e e o c c e s p e n d s t o " t h i s t o p i c " ~ a n E X C H [ S U B D : --3 n o d e c o r r e s p o n d s t o " t h i s p o i n t " ~ a D I A l [ B U B D ~-~'] n o d e e o r e e s p o n d s t o "a p o i n t t h a t n e e d e d o l a i ' i f i e a t i o n " , arld a n EXCH E S U B D : ÷ ] i i e d e o o e ~ ; ' e s p e n d s t o " w h a t w a s u n u l e a c " , E a c h HOVE i l l ] d e 1 2 e p r l ~ s e l ] t 5 ~311 u t t e e ~ J i i l ] e , (11 > [~oLll,~e. T h e seA; of HOVE n o d e s d o m i n a t e d b y EXC'.H [UI.IBO:"LI e o r e e s p e n d s t o " w h a t w a s s a i d ; t',he g e l r f ~ l , a ! l iln-~ of t h e O C i l V e c s a t i o n " , a l l d t i l e s e t o t HOVE n o d e s d o l , i i r i a t e d b y EXCFI ['31l[)1):+3 c o r r e s p o n d s t ( i " t h e ! i u b d i a l o g e e s " . t.J. k e w i s o ~ £H~'I; ~1 [if t i t tic>r il o d (,~ ~ ClOl2ices p o n t l i;o o51iel? h c l l a d e c ~ l o l l i e n t s el 6~ O C l i V e ~ ' s a t i o r l = T h e s e t 07 C()NV nod(.~>s o o r ' ~ ' e i l d s t t l " a l l t h e d i ] l t J ~ - e r l t ~ l e r i v i ! I c f J { ~ ] ; i e r l ~ )[ l i c i t i l l thi~,~ s e % s i o l l w i t h d . i . ~ t ~ r e r i t t l s o l , ' s " , t h e s e t i l l 1)i~%1. [ B U B D . ' - ' J 7iod{-#~5 (ltl!. e R ~ p o n d t ; t o " t l i ~ ! to~] il:;f7 (i(.iv()l~ed ,i i

tli~,~ s e t of F;XCH F B U B D ' - ] n e d ~ : q ~ ~ei:,i.,espsnd+~ t u " t h e lJoin~s d i s c u s s e d " , a n d +Je m i . B y t a k i n ( t J. n t n a c c o u n t o e n f i U u ~ ' a i , i o l t s o~ I e a t u e ~ ~It liodes ~ o n e oaii i s o l a t e , th~:~'efo~e, s u c h e l e m e n t s a ~ " t h e l a s t b u t c n e topi¢~ d i s c u s s e d b y t l ~ o p r e v i o u s u s e r " o r " t h e f l e e t p o i n t i~i t h i s o o e v e ~ ' s a t i c m t h a t n e e d e d o l a r i l i { l a t i o n " .

L e t u s n o w t u r n t o t w o e ) ( t e n s i o n s o~ t h e a b o v e s y s t e m ~ h y p e b h e t i e a l m o v e s arid a n t i c i p a t o c y m o v e s , ~ ' e q u i r e d b y c e r t a i n d i a l o g u e p h e n o m e n a .

4. H y p o t h e t i c a l m o v e s

" r h e e e a r e a p p a e e n t l y i n n o c u o u s C O i l V e p s a t i e n s s u o h a s (5) w h i c h m a y c a u s e ti~oob i e o n

f o r m a l g r o u n d s .

U: C a n y o u p r i n t t h e m i n u t e s Of t h e l a s t m e e t i n g ?

S: Y e s . D o y o u w a n t t o s e e t h e m ? U: Y e s

S: ( p ~ i n t s )

T h i s i s a f i v e - m o v e c o n v e r s a t i o n ( t h e s y s t e m ' s " Y e s " c o u n t s a s a s e p a c a t e m o v e ) . T h e g ~ a m m a c w o u l d a s s i g n t h e s t e u o t u e e s h o w n i n f o r m a l l y a s (6) t o t h e f i r s t f o u r m o v e s .

MOVE i i USER~ OPEN 1 , REQAFF MOVE 2: SYS'FEM, CLOSE i , SUPPAFF M O V E 3: SYSTEM, O P E N 2, R E Q A F F MOVE 4: USER, CLOSE 2, SUPPAFF

O n f o r m a l g r o u n d s , t h e o o n v e r s a t i o n is c l o s e d a f t e r t h e f o u r t h . m o v e (U: Y e s ) , w i t h

a l l OPENed moves having been CLOSEd. What,

t h e n , t r i g g e r ' s t h e s y s t e m ' s p r i n t i n g o f t h e e e q u i e e d t e x t ( M O V E 5) ~ a n d w h a t h a p p e n s a f t e r t h a t , S i n c e a n odd n u m b e c of m o v e s ~ a n n o t c o n s t i t u t e a w e l l - f o r m e d c o n v e r s a t i o n a e o e c d i n g t o t h e g r a m m a r p e e s e n t e d a b o v e ? It

is o l e a e t h a t i t is t h e m e a n i n g of M O V E 3 t h a t i s t h e k e y . T o h a n d l e t h i s f o ~ m a l l y , w e p c o p o s e t h e u s e o f t h e n o t i o n of " h y p o t h e t i c a l m o v e " a n d t h e c e p r e s e n t a t i o n s p e e c h aot.~ n e t a s a t o m i c e l e m e n t s Hilt a s s t r u o t u c e s . T h u s w e w i I ] u e p r e s e n t a s u p p I y - o ~ - a ~ f i ~ m a t i o n i n r e s p o n s e t o o c e q o e s t - l o c - - a f ~ i r m a t i o n as SUPPAFF(REgAFF)o A h y p o t h e t i u a l m o v e is a m o v e t h a t d o e s n o t a ~ t u a l l y o e e u r ilr t h e o e i l v e r s a t i o n $ b u t w h i c h t h e ~ i y s t e m o o s s t c u u t s o n lille b a s i s o~ v e r y s p e c i f i c c l u e s , a n d whic:h a l l o w it t o ( ~ o n t i n u e t h e eo~iw.~rsat i o n a p p c o p i ~ i a ~ i e i y ° T h e y ooz, c e s p e Y i d i n some w a y t o a ~ q ~ p c e s e n t a t i o n c~ G e i e e ' ~ ( 1 9 / 5 ) llotien o~ i m p l i o a t u r e . F o e ,E,~xample~ a m o r e d e t a i l e d a n a l y s i s o:~ (5) r e v e a l s t h a t (6) o m i t s s e v e r a l i m p o r t a n t d e t a i l s . T i l e f i r s t iilOVE! i s a b t u a l ly alailigtAous betwei:)n a ~ ' e q u o s t - : f o c - a f f i r m a t i o n a n d a ceqoe!~t-foz'-acM~ioli~ W h a t w e w o u l d like) t h e systelii t o d o i s t e supp).y b b e a f f i l ' i i l a t i o r i t e t h e r ' e q u e s t - ~ f o r ,-~ a l l i l ~ ' m a t i ( 3 n p a r t , j arid t o r e t l u ~ s t a l f i P i l i a t i o n c o n c t ~ c i l i f i g t h e e e q u e s t - - l e l . - : a e t i o n p a c t . T h ~

i m p o r t a n t p o i n t is t h a t a p[<epeP a n a l y . q i B of " O o y o u ~#ant t o s e e t h e ! m ? " s h o u l d r ' e p P e s e n t t h e J [ a e t t l ' i a t t h i s i s r e s p o n s e t o t h e p o t e n t i a l ~ ' e q u e s t . - f o r ~ a o t i o n i n t , e z ' p [ ' e t a t i o n of " C a n y o u p r i n t t h e m i n u t e s o f t h e l a s t m e e t i n g ? " 0 T h e u p s h o t of tliis is t h a t a m o r e p L ~ e c i s e ~ e p ~ ' e s e r i t a t i o n of t h e ~ i [ ' s t l o u t m o v e s e f (5) i s ( 7 ) , cathez' t h a n (6),.

M O V E i: U, ()PEN i, R E Q A F F / R E Q A C T H O V E 2: S, C L O S E i~ ~ U P P A F F ( R E Q A F F ) MOVE 3: B, OPEN 21 REQAFF(REQACT)

MOVE 4: U, CLOSE 2~ SUPPAFF(RESAFF(~E@ACT)

W e n e w h a v e a w a y of a m c o u n t i l l g f o ~ t h e s y s t e m ' s e e x t m o r e ( p m i n t i n g ) , a n d f e c e x p l a i n i n g why a n y t h i n g a t a l l happens.

MOVE 4 i s a SUPPAFF'(REQAFF(REQACT)), i . e ° a

However, t h i s r u l e must n o t o v e r - w r i t e t h e o r i g i n a l i n t e r p r e t a t i o n o f t h e i l l o o u t i o n a c y f o r c e o f t h e move, which must be r e t a i n e d f o c t h e d i a l o g u e t o be w e l l - f o r m e d w i t h r e s p e c t t o t h e grammar. We propose t h a t t h e e ~ f e o t o f t h i s t y p e o f r u l e (an i m p l i o a t u r e redundancy r u l e ) i s t ~ c r e a t e a h y p o t h e t i c a l move i m m e d i a t e l y f o l l o w i n g i t o f the a p p r o p r i a t e t y p e . I t s e f f e c t i s t o a l t e r t h e s t r u c t u r e o f t h e c o n v e r s a t i o n i n e x a c t l y t h e same way as i f t h e u s e r ( i n t h i s case) had a c t u a l l y u t t e r e d something l i k e " I r e q u e s t you t o p ~ i n t t h e minutes now", e x c e p t f o r t h e f a c t t h a t i t i s noted t h a t t h i s i s a h y p o t h e t i c a l move. We now have a f o r m a l e n t i t y t h a t can t r i g g e r t h e p r i n t i n o o f t h e r e q u i r e d t e x t , s i n c e t h i s i s a CLOSure of t h e h y p o t h e t i c a l move. I f no p r i n t i n g t o o k p l a c e , then t h e d i a l o g u e would b e i l l - formed, s i n c e i t would c o n t a i n one OPEN t h a t had n o t been CLOSEd. T h i s , t h e system i s

behaving as i f t h e use~ had made a

p a r t i c u l a r move t h a t d i d n o t a c t u a l l y o c c u r . (The n o t i o n ' a s i f ' i s c e n t r a l t o V a i h i n g e r ' s (1935) t h e o r y o f f i c t i o n s = I t i s a l ~ o c r u o i a l t o 6 r i o e a n i m p l i c a t u r e . )

The r e s u l t i s t h a t (4) i s now analysed as a s i x - m o v e d i a l o g u e , w i t h t h e s t r u c t u r e shown a~ ( 8 ) .

MOVE i : U, OPEN I , REQAFFIREQACT MOVE 2: S, CLOSE I , SUPPAFF(REQAFF) HOVE 3: S, OPEN 2, REQAFF(RE~ACT)

MOVE 4: U, CLOSE 2, SUPPAFF(REQAFF(REQACT)) MOVE 5: U, OPEN 3, RE~ACT, h y p o t h e t i c a l HOVE &: S, CLOSE 3, ACTION

5. A n t i c i p a t o r y m o v e s

A n o t h e r t y p e o f i r = e a l i s move i s an a n t i c i p a t o r y move, where on t h e b a s i s o f s p e c i f i c c l u e s t h e system a n t i c i p a t e s what t h e u s e r ' s n e x t m o v e w i l l be. The d i f f e r e n c e between t h e s e and h y p o t h e t i c a l moves i s t h a t no a c t i o n i s t a k e n by t h e system u n t i l t h e r e has been a r e a c t i o n from t h e user t h a t e i t h e r c o n f i r m s o r d i s o o n f i r m s t h e c o r r e c t n e s s o f t h e m o v e t h a t has been a n t i c i p a t e d . The use o f such moves w i l l be o f a s s i s t a n c e i n t h e i n t e r p r e t a t i o n of c r y p t i c f o l l o w - . u p s , as i n ( 9 ) .

u: Can you p r o v i d e p r o g r e s s r e p o r t s on LOKI s u b p r o j e o t s ?

S: Yes. Do you want t o see them?

U: LOKA

S: ( p r i n t s )

The u s e r ' s second u t t e r a n c e must be

i n t e r p r e t e d as a

r e q u e s t - f o r - a c t i o n ,

which i s d i f f i c u l t on f o r m a l grounds. W i t h o u t going i n t o t o o much d e t a i l , we propose t h a t

i n such oases t h s system should have

f o r m u l a t e d an a n t i c i p a t i o n o f a f o l l o w i n g

4 0

r e q u e s t ~ f o r - a c t i o n b e f o r e t h e u s e r ' ~ n e x t u t t e r a n c e . ] ' h i s c o u l d e i t h e r be an e ; ¢ p l i c i t r e q u e s t = f o r - a c t i o n ( " P l e a s e p r i n t t h e LOKA p r o g r e s s r e p o r t " ) , o r ~ i m p l y "Yes" ( i . e . a

SUPPAFF(REQAFF(REgACT))), which would

t r i g g e r a system r e q u e s t f o r c l a r i f i c a t i o n , perhaps, o r a n y t h i n g e l s e a t a l l tha~ can s e r v e t o i d e n t i f y t h e BASE o f t h e a n t i c i p a t e d r e q u e s t - f o r - a C t i o n . T h i s i s t h e i m p o r t a n t p o i n t about t h e a n t i c i p a t i e n ~ A n y t h i n g . a t a l l t h a t can f i l l i n t h e u n s p e c i f i e d ~ I o t s i n t h e BASE o f t h e a n t i c i p a t e d r e q u e s t - f o r - a c t i o n w i l l c o n f i r m t h a t t h i s u t t e r a n c e i s i n t e n d e d as a REQACT.

For t h i s reason~ t h e bare n a m e LOKA i ~

enough t o g e t t h e r e p o r t p r i n t e d . Any o t h e r s u f f i c i e n t l y i d e n t i f y i n g d e s c r i p t i o n o f t h e r e l e v a n t s u b p r c j e o t would have a c h i e v e d t h e same, such as any o f t h e f o l l o w i n g <as a p p r o p r i a t e ) : t h e one based i n Hamburg,

Hamburg, NL, Max'~ p r o j e o t ~ most ceeent~

e t c .

6 . C o n c l u s i o n s

The

processes

and f o r m a l i s m s o u t l i n e d above a r e a l l t e n t a t i v e i n n a t u r e , and

represent

p a r t o f an approach t o t h e problem o f

p r a g m a t i c s e n s i t i v i t y , r a t h e r than p u r p o r t e d s o l u t i o n s t o t h e problem. We e n v i s a g e then

as being p a r t o f a system t h a t uses a

m u l t i - l e v e l p a r s i n g t e c h n i q u e , w i t h mutual a s s i s t a n c e between d i f f e r e n t subcomponents o f t h e p a r s e r , so t h a t p r a g m a t i c i n f o r m a t i o n can i m m e d i a t e l y _i b e used t o a s s i s t p a r ~ i n g f o r s y n t a x , and so on. We a l s o see t h a t par~ing w i l l i n v o l v e n o t o n l y ~entence p a r s i n g , but a l s o c o n v e r s a t i o n p a r s i n g , i n t h a t t h e a p p r o p r i a t e s t r u c t u r e o f a c o n v e r s a t i o n must be b u i l t up a t each s t e p . T h i s i s s i m p l y one f u r t h e r p a r t o f t h e g e n e r a l p a r s i n g process~ but one t h a t we e n v i s a g e as being o f a s s i s t a n c e t o o t h e r p a r s e r suboomponents, as w e l l as f u l f i l l i n g i t s p r i m a r y f u n c t i o n o f making s u r e t h a t t h e system i s something o f a c o n v e r s a t i o n a l i s t ,

r a t h e r than j u s t being a communicative

REFERENCE~

Cole, P. & J. L, Morgan ( e d s . ) 1975. Syntax

& Semantios~ volume 3: S p e e o h a o t s . New

Yock= Aoademio Press

F i n d l e ~ N. V. ( e d . ) 1979. A s s o o i a t i v e

networks: r e p r e s e n t a t i o n and use o f

knowledge by oomputers". New York: Aoademio

Press

Given, To ( # d . ) 1979. SyntaH & Semantios~

volume 12: Oisoeuvse and s y n t a x . New York:

Aoademio Pcess

Gcioe, H. P. 1975 "Loglo and o o n v e r s a t i o n "

I n : Cole & Reagan ( e d s . ) , 1979,~41-58

Hobbs, 3. R. 1982. "TowacdB an understanding

e l ooherenoe in d i s o o u v s e " . I n : Lehnert &

Ringle ( e d s . ) , 1982, 223-243

Labov~ N. I772o S o o i o l i n ~ u i s t l o p a t t e r n s .

P h i l a d e l p h i a : U n i v e r s i t y of Pennsylvania

Press

Lehne='t~ |~. & M. H. Ringle (ed=.) 1982.

S t r a t e g i e s f o F n a t u r a l language prooessing.

London= Erlbaum

MoKeown, I(. R. 1985. "Discourse s t r a t e g i e s

f o r g e n e r a t i n g n a t u r a l - l a n g u a g e t e x t " . I n :

A r t i f i o i a l Zntelligenoe~27~ I - / , I

V a i h i n g e r , H. 1935. The p h i l o s o p h y of 'As

i f ' - - a system of the t h e o r e t i o a l ~

p r a o t i o a l and r e l i g i o u s f i o t i o n s of mankind. London: Routledge & Kegan Paul

Waohtel~ T. 1985a. "Disoourse s t c u o t u c e " .

LOKI Report N L I - I . I ~ U n i v e r s i t y of Hamburg

Waohtel~ T. 1985b. "Guided speeoh aot

assignment i n 'oan you' u t t e r a n o e s "

Unpublished L O K I working paper TW-II,

U n i v e r s i t y of Hamburg

Waohtel~ T. 1985o. " C o n t e x t u a l f a o t o c s in

speeoh a o t assignment". Unpublished LOKI

working paper TW-13, U n i v e r s i t y of Hamburg