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CSA3180: Natural Language Processing

Explore character repertoires, encoding methods, and common corpora in text processing. Learn about Unicode, encoding algorithms, and applications like search engines. Dive into large document collections, hierarchical structures, and NLP with examples like Google.

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CSA3180: Natural Language Processing

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  1. CSA3180: Natural Language Processing Text Processing 1 Language Encoding Issues Common Corpora Handling Large Document Collections Applications: Anatomy of a Search Engine NLTK CSA3180: Text Processing I

  2. Language Encoding Issues • Different encoding methods • Different languages • Unicode Standard • Further information: • Unicode Consortium • Jukka Korpela Tutorial http://www.cs.tut.fi/~jkorpela/chars.html CSA3180: Text Processing I

  3. Language Encoding Issues • Character Repertoire – set of distinct characters • Character Code – mapping between characters and positive integers • Character Encoding – algorithm for presenting characters using particular code CSA3180: Text Processing I

  4. Language Encoding Issues • Encoding using octets • Common Encodings: • ASCII • ISO Latin I (ISO 8859-1) • ISO Latin II + III Extensions (for Maltese) • Unicode & UTF-8 • ANSI • Cyrillic and Chinese Encodings CSA3180: Text Processing I

  5. Language Encoding Issues • Text encoding on the Web • MIME Standard • Content-Type: text/html; charset=iso-8859-1 • Used in Email and Web Servers • Problems in implementation: few encodings properly supported • UTF-8 recommended CSA3180: Text Processing I

  6. Common Corpora • WordNet • TREC/ACE/TIDES Corpora • Linguistic Data Consortium (LDC) • GigaWord (News) • Tree Banks • MUC (Message Understanding Conference) • TIPSTER (Information Retrieval) CSA3180: Text Processing I

  7. Handling Large Document Collections • Special issues involved in processing • Hierarchical directory structures • File indexes • Batch processing – start, resume, pause, end • Job scheduling CSA3180: Text Processing I

  8. Applications • Anatomy of a Search Engine (Larry Page and Sergey Brin) • Describes the internals of Google • NLP in everyday life! CSA3180: Text Processing I

  9. Next Sessions… • Natural Language Toolkit (NLTK) • http://nltk.sourceforge.net/ • Please download and install! CSA3180: Text Processing I

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