TULIPS - Teachable, Understanding Natural Language Input Problem-Solver

Th is paper desc r ibes the p r i n c i p a l f e a t u r e s of TULIPS program designed as a w i d e l y o r i e n t e d A I system t h a t accepts n a t u r a l language (NL) i n p u t . NL processor o f TULIPS is guided by i n f o r m a t i o n r e p r e sented i n models o f c u r r e n t " e x t e r n a l w o r l d " domain and of c u r r e n t user and u t i l i z e s deduc t i ve and i n d u c t i v e mechan isms. These f ea tu res a l l o w the program: t o d i scove r the most r e l e v a n t i n t e r p r e t a t i o n o f an i n p u t , t o e x t r a c t the d e s c r i p t i o n s o f u s e r ' s goa ls from NL u t t e r a n c e s , and to generate the s o c a l l e d T-problems ( T f o r TULIPS). Having so lved them TULIPS not on ly answers u s e r ' s request but a l so l e a r n s new knowledge on i t s e n v i ronment and improves i t s own mechanisms. I n t r o d u c t i o n I t need h a r d l y be sa id about a t t r a c t i veness of NL communications w i t h a p r o gram. TULIPS's user must no t l e a r n s p e c i a l i n t e r a c t i v e languages and can pass to a computer not a f o r m a l i » e d d e s c r i p t i o n o f the a l g o r i t h m bu t a d e s c r i p t i o n o f the problem i t s e l f ( an i n p u t f o r prob lems o l v i n g b lock o f the program ) • I t must be e s p e c i a l l y emphasised t h a t NL d e s c r i p t i o n of a problem can be of the p r e l i m i nary i n f o r m a l k i n d . For TULIPS i s i m p l e mented as a d i a l o g s y s t e m , user is ab le to s p e c i f y and supplement t h i s d e s c r i p t i o n i n case o f need. Thus TULIPS c a r d i n a l l y d i f f e r s f rom " t r a d i t i o n a l " computer program. I t i s not a d e t a i l e d fo rma l d e s c r i p t i o n o f an a l g o r i t h m f o r the c u r r e n t u s e r ' s problem, but a genera to r o f such a l g o r i t h m s . I t r ece i ves as i npu t not a command to a c t i va te known to user B t r i c t segment o f a l g o r i t h m , but on ly a d e s c r i p t i o n o f u s e r ' s problem ( i . e . user s a i s what he wants w i t h o u t any s p e c i f i c a t i o n how i t Bhould be done ) . Jus t t h i s p rope r t y of TULIPS i t s a b i l i t y a u t o m a t i c a l l y so lve the prob lem, be ing t o l d t he word ing o f i t a l l ows to cons ide r the program as AI sys tem t h a t automat izes so n o n t r i v i a l f u n c t i o n s o f human i n t e l l i g e n c e as s p e c i f y i n g of a problem to the w e l l f o r m e d one and s o l v i n g o f such w e l l f o r m e d prob lem. H i g h l y i n t e l l i g e n t work does, however , not on ly the So lve r of TULIPS but a l s o i t s Ana lyse r . I t s goal i s t o e x t r a c t f rom NL (Russian) i npu t the d e s c r i p t i o n s o f problem s i t u a t i o n s , u s e r ' s goa l s , and own d u t i e s ( represented in u t te rances bo th e x p l i c i t l y and i m p l i c i t l y ) . To ext r a c t i m p l i c i t i n f o r m a t i o n the Analyser should take i n t o c o n s i d e r a t i o n a contex t ( l o c a l and g l o b a l ) o f the cu r ren t commun i c a t i o n p rocess . A l o c a l con tex t of NL u t t e r a n c e i s an i n f o r m a t i o n ex t rac ted f rom the p rev ious i n p u t exp ress ions . A g l o b a l con tex t i s de f i ned by models o f " a b s t r a c t " u s e r , " e x t e r n a l w o r l d " as a who le , p a r t i c u l a r users known f o r TULIPS, s p e c i f i c problem-domains ( o f u s e r ' s a c t i v i t y ) , "gene ra l d u t i e s " o f TULIPS, and concre t h e u r i s t i c s and o the r t o o l s r e l a t ed to a concre t problem-domain or u s e r . These k inds of models must be i n t r o duced because of TULIPS is a w i d e l y o r i ented system. The program is to so l ve d i f f e r e n t k indes o f problems i n d i f f e r e n t concre t domains and to adapt to subset of Russian be ing used, s p e c i f i c f ea tu res o f problem-domains and u s e r s . Th is main f e a t u r e of TULIPS w i d e o r i e n t a t i o n de termines a l l the o the r i t s f ea tu res and, in p a r t i c u l a r , the approach to NL p roces -