DEALING WITH AMBIGUITIES IN ENGLISH CONJUNCTIONS AND COMPARATIVES BY A DETERMINISTIC PARSER
Rey‐Long Liu, Von‐Wun Soo · International Journal of Pattern Recognition and Artificial Intelligence · 1990
The major problems in parsing English conjunctions and comparatives are ambiguities of scoping and ellipsis. Scoping ambiguities occur when a parser cannot deterministically detect boundaries of constituents, while ellipsis ambiguities occur when a parser cannot deterministically detect missing components. Since simple lookahead mechanisms cannot collect adequate information to resolve these ambiguities, a parsing strategy that only employs such mechanisms will need to backtrack each time it makes incorrect assumptions. In this paper, we extend the Wait-And-See strategy to parse conjunctions and comparatives deterministically and simultaneously. Several mechanisms, such as bottom-up preparsing, suspension, and pattern matching, are implemented. The bottom-up preparsing accesses the dictionary and recognizes isolated sentence fragments which can be determined without ambiguities. The suspension, which is different from Marcus’s attention shifting, allows the parser to suspend temporally at ambiguous points and continue to parse the rest of the sentence until it obtains the necessary information to resolve the ambiguities. Pattern matching uses the concept of symmetry to detect missing components (the ellipses) in the two conjoined or compared sentence fragments.