Part of Speech Tagging

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Summary

Part of Speech Tagging (or POS Tagging for short) is a task in the field of computational linguistics which looks at marking a text corpus with the associated word categories known as parts of speech to words.

Common Approaches

Some common approaches to POS Tagging include the following:

  • Hidden Markov Models based approaches, sometimes referred to as stochastic algorithms in older literature
  • Dynamic Programming/Viterbi-like algorithms (DeRose & Church)
  • Unsupervised approaches: Brill Tagger (Transformation-based learning), Constraint Grammar, Forward-Backward

Example Systems

  • FastTag - open source implementation of Brill Tagger
  • OpenNLP Tagger - based on maximum entropy
  • CRF Tagger - based on conditional random fields
  • LingPipe - tool kit that contains models for POS tagging

References / Links

  • Wikipedia article on Part of Speech Tagging - [1]
  • Webpage with download links to many different POS taggers, from Statistical natural language processing and corpus-based computational linguistics: An annotated list of resources - [2]