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CS 479, section 1: Natural Language Processing

This work is licensed under a Creative Commons Attribution-Share Alike 3.0 Unported License . CS 479, section 1: Natural Language Processing. Lecture # 38: Phrase-based Translation. Lecture content by Eric Ringger, Dan Klein of UC Berkeley, and Phillip Koehn formerly of ISI.

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CS 479, section 1: Natural Language Processing

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  1. This work is licensed under a Creative Commons Attribution-Share Alike 3.0 Unported License. CS 479, section 1:Natural Language Processing Lecture #38: Phrase-based Translation Lecture content by Eric Ringger, Dan Klein of UC Berkeley, and Phillip Koehn formerly of ISI.

  2. Announcements • Reading Report #14on phrase-based translation • Due: Wednesday (online) • Last one! • Final Project Reports • Due: today • Last day to submit work • The last day of instruction for the semester (Thursday), 12/6 • Final Exam: • Comprehensive • Review in Class on Wednesday • Come prepared with your questions!

  3. Objectives • Understand phrase-based methods for statistical MT • See (near) state-of-the-art results for MT from the phrase-based approach • See a negative result for syntax in statistical MT

  4. Phrases in Word-Alignment Models Target: Source: Restriction: multiple words in the source language can align with a single word in the target language, but not the other way around. For word-alignment models, Direction Matters!

  5. Phrase-Based Alignment

  6. The Pharaoh Model (in abstract)

  7. The Pharaoh Model (in detail)

  8. Bidirectional Alignment

  9. Heuristic: Grow Diagonally

  10. Heuristic: Attach Neighbors

  11. Alignment Heuristics

  12. Phrase Size

  13. Alternative:Joint Phrase Alignment Model

  14. Sources of Alignment

  15. Lexical Weighting

  16. How to Translate?

  17. The Pharaoh Decoder

  18. The Pharaoh Decoder

  19. Hypothesis Lattices

  20. Pruning but not admissible

  21. Significance • Inspired fruitful follow-up work involving phrase-based and syntax-based statistical MT.

  22. Next • Co-reference Resolution

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