Collocational Grammar as a Model for Human Computer Interaction

COLLOCATIONAL GRAMMAR AS A MODEL FOR H I NAN-COMPUTER INTERACTION

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C o n t r a r y t o t h e l o n g - h e l d b e l i e f o f t r a n s f o ~ n a t i o n a l E ~ m m a r i a n s f o r c o m m u n i c a t i o n i n g e n e r a l , t h e m a j o r i t y c f natural languaEe sentences which people actually use in oom- m u n i c a t i n g w i t h a c o ~ p u t e r , i n a n u n c o n s t r a i n e d mode, a r e n o t n o v e l . As Thompson and Thompson 1981s660 o b s e l w e z " m o n o t o n y o f s t r u c t u r e i s t h e r u l e r a t h e ~ t h a n t h e e x c e p t i o n i n homan- - c o m p u t e r c o m m u n i c a t i o n . " Thompson 1981"41 r e p o r t s i n h e r study of such communications that 75 percent of the queries w e r e w h - q u e s t i o n s , 1% p e r c e n t w e r e commands, 5 p e r c e n t w e r e s t a t e m e n t s , and 1 p e r c e n t w e r e y e s / n o q u e s t i o n s .

The r e p e t i t i v e f e a t u r e o f n a t u r a l l a n g u a g e i s n o t a new c o n c e p t . S i m i l a r o b s e r v a t i o n s h a v e b e e n made b s f o r e o Damerau 1971 u s e d c o l l o c a t i o n o f l e x i o a l i t e m s a s t h e b a s i s f o r a Marker m o d e l i n a n e x p e r i m e n t f o r t e x t g e n e r a t i o n . B e c k e t c l a i m s t h a t " t h e w o n d e r f u l f e a t s o f t h e homan i n t e l l e c t . . , a r e b a s e d a s much on m e m o r i z a t i o n a s on a n y impromptu p r o b l e m - -solving" (1975:62). He posits a phrasal lexicon oonslstln~ of six major categories of lexioal phrases by which we "stitch t c g e t h e r s w a t c h e s o f t e x t t h a t we h a v e h e a r ~ b e f o r e | p r o d u c t - i v e p r o c e s s e s h a v e t h e s e c o n d a r y r o l e o f a d a p t i n g t h e o l d phrases to the new situations" (1975z60)o

c o - o c c u r . T h i s s u r f a c e c o - o c c u r r e n c e i s t h e r e s u l t o f what may a t t i m e s be c o m p l i c a t e d s y n t a c t i c and s e m a n t i c i n t e r r e l a t -

i o n s o f l a n g u a g e u n i t e . U n f o r t u n a t e l y , a s y s t e m a t i c a c c o u n t - i n g o f t h e s e i n t e r r e l a t i o n s h a s n o t b e e n a c h i e v e d i n any l i n g u i s t i c t h e o r y . The t h r u s t o f o u r a p p r o a c h i s t h a t t h e more o f l a n g u a g e w h i c h c a n be h a n d l e d l e x i c a l ! y , t h e e a s i e r w i l l homan l a n g u a g e be a b l e t o be m o d e l l e d .

A c t u a l d a t a on t h e f r e q u e n c y o f l e x i c a l c o l l o c a t i o n a r e v e r y s p a r e s . A s t u d y o f word s e q u e n c e s i n PANALOG t e x t h a s shown a s u r p r i s i n g amount o f r e p e t i t i o n o f word s e q u e n c e s (Bienstock and Smith in preparation). (PANALOG is a system for passing messages among small ~ o u p s in computer confer- enclng with telemall and calendar features. See Housman 1979. The data are of human-homan communication and not homan- -computer cc~.,nunication and are thematically restricted. They t h e r e f o r e r e s e m b l e D a m e r a u ' s d a t a . ) A s t u d y o f p a r t s o f t h e Brown E n g l i s h Corpus has b e e n u n d e r t a k e n i n o r d e r t o g e t l e s s t h e m a t i c a l l y homogeneous m a t e r i a l . I n a d d i t i o n , W i z a r d o f OZ e x p e r i m e n t s w i t h u n c o n s t r a i n e d h , - . a n - c o m p u t e r i n p u t w i l l b e - g i n s o o n a t GTE L a b o r a t o r i e s i n o r d e r t o g a t h e r t h e more r e l e v a n t human-oomputeu~ d a t a .

A PANALOG t e x t o f 16,133 words c h o s e n f o r s t u d y . The l o n g e s t s t r i n g w h i c h o c c u r r e d more t h a n once was a s e v e n word q u o t e from N t e t z s c h e . Two s i x - w o r d s t r i n g s o c c u r r e d t w i c e and a t l e n g t h f i v e , one o c c u r r e d t h r e e t i m e s and t h i r t e e n w e r e r e p e a t e d t w i c e .

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Figure i. String Length

T h i s i s a r e v e a l l ~ m e a s u r e o f t h e Amount o f r e p e t i t i o n i n a t e x t o f t h i s l e n g t h . I n p a r t i c u l a r , r e c u r r i n g two word s t r i n g s a c c o u n t f o r 4 0 . 8 p e r c e n t o f t h e r u n n i n g t e x t a n d r e - c u ~ r i n g t h r e e word s t r i n g s c o m p r i s e 8 . 1 p e r c e n t o f t h e t e x t .

The b a s i c a s s u m p t i o n of t h e f r e q u e n t o c c u r r e n c e o f l e x i c - a l c o l l o c a t i o n i n n a t u l - a l l a n g u a g e t e x t s , e s p e c i a l l y i n

h , - , a n - o c m p u t e r c o m m u n i c a t i o n , i s t h e b a s i s f o r t h e d e v e l o p m e n t o f a new t y p e of n a t u r a l l a n g u a g e p r o c e s s o r . F o r d , 1981, h a s c o n s t r u c t e d a n a t u r a l l a n g u a E e p r o c e s s i n g s y s t e m f o r d a t a b a s e u p d a t i n g , r e t r i e v a l , and m a n i p u l a t i o n t which r e l i e s c r i t i c a l l y on t h e o b s e r v a t i o n t h a t r e a l u s e r s t e n d t o employ a v e r y l i m i t e d s e t .of l e x i c a l d t r i ~ t y p e s i n q u e r y i ~ d a t a b a s e s .

The F o r d n a t u r a l l a n g u a g e p r o c e s s o r c o n s i s t s o f a two s t a g e r e d u c t i o n a l g o r i t h m f o r ~ r a n s l a t i n g n a t u r a l l a n g u a E s i n - p u t s i n t o b a s i c f u n c t i o n s which a r e t h e n u s e d t o p e r f o r m t h e q u e r y . The f i r s t s t a g s o f t h e r e d u c t i o n c h a n g e s t h e i n p u t words t o m e a n i n g r e p r e s e n t a t i o n s u s i n E a l i s t o f l e x i o a l i t e m s a n d a m e a n i n g c o r r e l a t e l i s t . The s e c o n d s t a g e t a k e s a s i n p u t s t r i n g s of t h e s e m e a n i n g c o r r e l a t e s and o h a ~ e s them i n t o b a s i c l l s t .

409 n u m e r i c r e p r e s e n t a t i o n s f o r words mapped down t o 132

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t o 19 f u n c t i o n s . T h i s two s t a g e r e d u c t i o n scheme worked e f f i c i e n t l y enough t o r e s p o n d t o 9 3 . 8 p e r c e n t o f t h e

1697

i n - p u t q u e r i e s , i n c l u d i n g u n g r a m m a t i c a l ones from i n e x p e r i e n c e d u s e r s , w i t h a r e s p o n s e t i m e o f 1.5 s e c o n d s , o p e r a t i n g i n a n e n v i r o n m e n t o f 90K 8 - b i t b y t e s . T h i s compares v e r y f a v o r a b l y t o Thompson 1981 where o n l y 6 7 . 7 p e r c e n t o f REL q u e r i e s were c o r r e c t l y p a r s e d w i t h a n a v e r a g e r e s p o n s e t i m e o f 10 s e c o n d s . (Space r e q u i r e m e n t s were n o t r e p o r t e d . ) S i m i l a r l y , Damerau 1981 and P a t r i c k 1981 r e p o r t a s u c c e s s r a t e f o r TQA o f 6 5 . 1 p e r c e n t i n p u t s c o r r e c t l y p a r s e d w i t h t h e t i m e r e q u i r e d t o p r o c e s s a s e n t e n c e t y p i c a l l y b e i n g 10 s e c o n d s .

The r e a s o n why t h e s y s t e m works so w e l l i n t e r m s o f a c c u r a c y , s p e e d , and s m a l l s t o r a g e r e q a i r e m e n t s i s b a s e d on t h e two s t a g s r e d u c t i o n t e c h n i q u e w h i c h , i n t ~ r n , i s b a s e d on t h e f a c t t h a t a g r e a t ma~v i n p u t s i n h u m a n - c o m p u t e r communic- a t i o n

are repetitious syntactically, semantically, and lexl-

~ally. Repetition is a principal characteristic of human-

-computer

c o m m u n i c a t i o n .

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