1 An Introduction to Computational Linguistics Mohammad Bahrani

2 References: Ruslan Mitkov, “The Oxford Handbook of Computational Linguistics”, Igor Bolshakov, Alexander Gelbukh, Computational Linguistics, Models, Resources, Applications, James Allen, Natural Language Understanding, Daniel Jurafsky, and James Martin, Speech and Language Processing, 2 nd Edition, 2009.

3 Computational Linguistics Definition: –Computational linguistics is an interdisciplinary field dealing with the statistical and/or rule- based modeling of natural language from a computational perspective.

4 Interdisciplinary research... Psychology, Cognitive Science Linguistics Philosophy Computer Science, Artificial Intelligence

5 Levels of language analysis Phonetics/phonology morphology Syntax Semantics Pragmatics Discourse

6 Levels of language analysis 1.Language is one of fundamental aspects of human behavior and is crucial component of our lives. 2.Green frogs have large noses. 3.Green ideas have large noses. 4.Large have green ideas nose.

7 NLP: techniques Text Segmentation and Normalization Morphological Analysis Part-of-Speech Tagging Parsing (Syntactic Analysis) Semantic Analysis –Word Sense Disambiguation Language Modeling Machine learning …

8 NLP: applications Natural Language Understanding –Spoken Language Understanding Document processing –information extraction –summarization –topic identification –document clustering Information retrieval –text retrieval –Spoken document retrieval

9 NLP: applications Machine translation Text generation Spell and grammar checking Speech recognition Text-To-Speech synthesis Optical Character Recognition (OCR)

10 NLP: applications Spoken Dialogue Systems Question Answering Systems Speech to Speech Translation