PET: Processing English Text

This paper d e s c r i b e s a new p a r s e r t h a t combines t o p down and bot tom up s t r a t e g i e s and the n a t u r a l l a n g u a g e p r o c e s s i n 6 sys tem PET which u s e s t h e p a r s e r . PET i s d e s l g n e d t o f a c i l i t a t e t h e i n t e r a c t i v e c o n s t r u c t i o n o f n a t u r a l l anguage f r o n t ends and t o suppo r t e x p e r i m e n t s i n c o m p u t a t i o n a l l i n g u i s t i c s ° The sys tem, which has been implemented i n UT-LISP, p r o v i d e s f a c i l i t i e s f o r p e r f o r m i n g t h e f o l l o w i n g t a s k s : n a t u r e l l anguage p a r s i n g a c c o r d i n g t o c o n t e x t f r e e and t r a n s f o r a a t i o n a l grammars; d t s e m b t ~ a t i o n o f word s e n s e s by p a t t e r n d i r e c t e d i n f e r e n c e ! c o n s t r u c t i o n o f a s e m a n t i c ne twork d a t a base from E n g l i s h s e n t e n c e s ; d e d u c t i v e i n f o r m a t i o n r e t r i e v a l t o answer s i m p l e E n g l i s h q u e s t i o n s °