1. 1 CSI 5180: Topics in AI: Natural Language Processing, A Statistical Approach Instructor: Nathalie Japkowicz e-mail: nat@site.uottawa.ca Objectives of the Course and Preliminaries

2. 2 Why study Natural Language Processing (NLP)? 4 NLP is a very important current area of investigation as it is necessary to many useful applications. 4 These applications include: information retrieval, extraction, and filtering; intelligent Web searching; spelling and grammar checking; automatic text summarization; pseudo- understanding and generation of natural language; and multi-lingual systems including machine translation.

3. 3 Why study NLP Statistically? 4 Up until the late 1980’s, NLP was mainly investigated using a rule-based approach. 4 However, rules appear too strict to characterize people’s use of language. 4 This is because people tend to stretch and bend rules in order to meet their communicative needs. 4 Methods for making the modeling of language more accurate are needed and statistical methods appear to provide the necessary flexibility.

4. 4 Subdivisions of NLP 4 Parts of Speech and Morphology (words, their syntactic function in sentences, and the various forms they can take). 4 Phrase Structure and Syntax (regularities and constraints of word order and phrase structure). 4 Semantics (the study of the meaning of words (lexical semantics) and of how word meanings are combined into the meaning of sentences, etc.) 4 Pragmatics (the study of how knowledge about the world and language conventions interact with. literal meaning).

5. 5 Topics Covered in this course 4 Studying Words: –Collocations –Statistical inference –Word sense disambiguation –Lexical Acquisition 4 Studying Grammars: –Markov Models –Part-of-Speech Tagging –Probabilistic Context Free Grammars 4 Application: Statistical Alignment and Machine Translation

6. 6 Tools and Resources Used 4 Probability/Statistical Theory: Statistical Distributions, Bayesian Decision Theory. 4 Linguistics Knowledge: Morphology, Syntax, Semantics and Pragmatics. 4 Corpora: Bodies of marked or unmarked text to which statistical methods and current linguistic knowledge can be applied in order to discover novel linguistic theories or interesting and useful knowledge organization.

7. 7 Course Requirements 4 4-6 written and programming assignments (40%) 4 An in-class presentation of a current research paper (10%) 4 A Mid-Term (20%) 4 A Final Project (30%)

8. 8 Textbook and other useful information 4 Foundations of Statistical Natural Language Processing, by Chris Manning and Hinrich Schutze, MIT Press. 4 Current literature available from the Web will be used for class presentations. 4 Class’ Website: http://www.site.uottawa.ca/~nat/Courses/ csi5180_fall_2003.html 4 Check the class website for a companion website for the textbook and other statistical NLP resources.