An Object-Oriented Parser for Text Understanding

The parser is par t of a t e x t understanding system in which s t r u c t u r a l ambiguity is a major problem. A l l components of the system use a message-passing con t ro l s t r u c t u r e . A general advantage of t h i s form of con t ro l is tha t i t a l lows the f l e x i b l e i n t e g r a t i o n of d iverse knowledge sources. The parser t ransmi ts sub-sen ten t ia l cons t i tuen ts f o r semantic i n t e r p r e t a t i o n . A pseudo-para l le l vers ion of the l e f t c o r n e r pars ing a lgor i thm wi th top-down f i l t e r i n g is used. As b l i n d t ransmiss ion would send spurious c o n s t i t u e n t s , a delay mechanism is used to queue cons t i tuen ts u n t i l a l l a l t e r n a t i v e analyses of a segment have been completed.