Natural Language Processing
NLP is among the oldest Artificial Intelligence efforts. The
famous Turing Test was largely an NLP problem.
- Original applications were connected to machine
translation of online texts (of Russian physics papers).
- The original approach was word-by-word using dictionary
lookup. This didn't work because of word-sense ambiguity. In one
famous example, this:
"In recent times Boolean algebra has been successfully employed
in the analysis of relay networks of the series-parallel type."
translated to this:
"(In, At, Into, To, For, On, N) (last, latter, new, latest,
worst) (time, tense) for analysis (and, N) synthesis
electrical (circuit, diagram, scheme) parallel- (series,
consecutive, consistent) (connection, junction, combination)
from) (success, luck) (to be utilize, to be take advantage of)
apparatus Boolean algebra."
- The next approach was through grammatical analysis.
- This started with the mathematical study of language in
terms of their expressive power.
- Noam Chomsky (1957) created the
first taxonomy of languages: regular, context-free,
context-sensitive, and unrestricted. With the
- With the corresponding taxonomy of machines: finite
automata, stack machine, bounded automata, and Turing Machine.
- This approach attempts to "understand" language from a
structural perspective. Tokens are identified, parts of speech
are assigned, and grammatical relations are also assigned:
subject, verb, direct object, indirect object, prepositional
phrase attachment, and so forth.
- This approach is prone to fail in the event of structural
ambiguity, for example:
- "The man hit the boy with the stick"
- Who is holding the stick?
- Applications of NLP grew large and varied:
- Natural Language Interface
- Question Answering Systems
- Text Processing (spelling and grammar checking)
- Speech Processing
- Machine Translation
T, Mar 24, 1998; 27Feb91
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