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Book Description:
This book is the second volume in a set of two books with the same title, but different undertitle, organized around two scientifically distinct but, in fact, strictly interrelated fields of research:
* sentence level linguistic phenomena
* text or discourse level linguistic phenomena
where the former is to be described by means of grammatical theories, the latter requires the intervention of extralinguistic knowledge, i.e. knowledge of the world, appropriately stored in lexica or ontologies. the books are organized mainly as an experimental exercise: they illustrate the theoretical background with the output of the system, GETARUNS, that enacts and applies the theory. The architexture of the system is strictly related to the structure of the books.
BOOK 1- the current book-addresses sentence grammar or what is usually referred to as such by theoretical linguists. It does it by dividing up - somewhat ideally and sometimes arbitrarily- what must or needs to be computed at sentence level from what needs not or cannot be computed at the same level, and consequently belongs to discourse grammar. The books also indirectly do another (un)intended subdivision: the one existing between syntax and semantics. Again, it would be impossible not to deal with semantically related issues when talking about syntax or the lexicon. However, semantics with uppercase S, is only treated in Book 2 (already published) where discourse and text level grammar is tackled.
Therefore, this book deals with all that concerns the level of sentence grammar in a computational environment, i.e. sentence level parsing. In our approach, knowledge of the world and semantic disambiguation do not interfere with the rules of sentence grammar, and can be thought of as a separate level of computation, provided the lexicon can be structured in such a way to allow a neat subdivision of tasks.
COMMENT ON THE CD-Rom:
We decided to include the system in its various implementations in a CD-Rom attached to the book. GETARUNS comes in three versions:
Version 1. Complete Getaruns: performs a complete analysis of a text from tokenization to discourse structure. This version also supports the fully topdown parser for grammatically checking. It also implements questions answering with a generator;
Version 2. Partial Getaruns: also performs a complete analysis but does it in a fully bottomup version, only checking for broad semantic constraints. No temporal reasoning, no logical form, no semantic discourse model. It builds a fully indexed augmented dependency structure which is then used to produce a level of informational structure. This is used to produce discourse relations and discourse structures. It is also used to evaluate entailment relations:
Version 3. Shallow Getaruns: can be used to do sentence extraction on the basis only of tagging and local discourse perusal based on discourse markers. It can also be used to do the same thing on a shallow version of the Partial Getarun, which we called Deep Summarization. It also implements a version of Question Answering based on sentence extraction as best candidate answers. |
