Journal of Artificial Intelligence Research
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This report is a user''s manual for the TRAINS-95 parsing system. An accompanying report describes the grammar used in TRAINS-95, and the robust speech act interpretation system, which takes the chart and produces a series of speech acts that best characterize it. The parser is based on the bottom-up parser described in Natural Language Understanding, Second Ed. (Allen, 1994, Chapters 3, 4, and 5). It uses the same formats for the grammar and the lexical entries, and the same basic bottom-up algorithm. There are a number of extensions beyond the basic system described in the book, each of which will be discussed in this report, including: (1) support for parsing word lattices; (2) best-first parsing using context-free probabilistic rules; (3) incremental (word by word) parser with backup for corrections; (4) hierarchical feature values and extended unification options; (5) a hierarchical lexicon entry format that simplifies defining large lexicons; and (6) procedural attachment to chart actions.