A Structure for the Representation of Knowledge: A Proposal for a Micro-Actor

I . I n t r o d u c t i o n A q u e s t i o n a n s w e r i n g sys tem is a compos i te of subsys tems o f l anguage a n a l y s i s , i n f e r e n c e and l anguage g e n e r a t i o n . I n t h e i n f e r e n c e sys tem, a u s e f u l and f l e x i b l e s t r u c t u r e i s needed f o r t h e r e p r e s e n t a t i o n o f know ledge . There a re two ways o f r e p r e s e n t i n g knowledge i n c o m p u t e r s : t h e a s s e r t i o n o f f a c t s and t heo rems . A m i c r o a c t o r , w h i c h possesses some o f t h e a t t r i b u t e s o f a c t o r s (C. H e w i t t 1 9 7 3 ) , i s i n t r o d u c e d t o c o n s t r u c t a knowledge r e p r e s e n t a t i o n s t r u c t u r e . Knowledge i s p r o c e d u r a l l y embedded i n m i c r o a c t o r s s o i t i s easy t o r e p r e s e n t theorems a n d , s i n c e each m i c r o a c t o r has a s t a c k f o r d a t a , i t i s a l s o p o s s i b l e f o r v a r i o u s k i n d s o f f a c t s t o b e s t o r e d . A c t o r i s i ndeed u n i v e r s a l a n d , a l t h o u g h compl i c a t e d , I s c o m p a t i b l e w i t h a l l p rogramming l a n guages and h a r d w a r e . However, i t i s n o t s o easy t o r e a l i z e p r e c i s e l y such a c o m p l i c a t e d s y s t e m . For examp le , a p s e u d o i m p l e m e n t a t i o n o f c o r o u t i n e p r o c e s s i n g o r p a r a l l e l p r o c e s s i n g w i l l r educe t h e e f f i c i e n c y o f t h e s y s t e m . We, t h e r e f o r e , i n t r o duce a m i c r o a c t o r based on t h e concept o f a c t o r , and use i t a s t h e knowledge base . M i c r o a c t o r r e t a i n s t h e ma in c h a r a c t e r i s t i c s o f a c t o r . U s i n g a LISP sys tem on a p a r a l l e l p r o c e s s o r , a m i c r o a c t o r sys tem w i l l b e e a s i l y imp lemen ted .