Introduction to Computational Linguistics

1. Lecture 1 Introduction to Computational Linguistics Dr. Radhika Mamidi ENG 270

2. What is Linguistics? • The scientific study of human language • Aim is to establish a theory by studying nature of a language and by applying this established theory to describe other languages • Descriptive study not prescriptive • Speech activity - speaker, hearer, setting, code, medium; plus topic, contextual knowledge, abiding social norms, communicative competence

3. Applied Linguistics Subfields / Inter-disciplinary fields: Sociolinguistics Lexicography Stylistics Computational Linguistics Semiotics Psycholinguistics Language Teaching/Learning Translation Studies Anthropological Linguistics Note: Now ‘Applied Linguistics’ is associated with Lg teaching.

4. What is Computational linguistics? “Computational linguistics is an interdisciplinary field dealing with the statistical and logical modeling of natural language from a computational perspective.”

5. Goal of Computational linguistics • To make the computers understand human language. • To use technology to build language tools. • Use computers to process or produce human language. We want to communicate with computers in the language we speak!

6. WhyComputers should talk with us? • The main obstacle in the interaction between human and computer is communication problem. • Computers do not understand our language and learning computer language is difficult. • Computer language do not match the structure of human thought. • The use of human language in computer applications will benefit the user.

7. Most interesting CL application: chatbot • A chatterbot (or chatbot) is a type of conversational agent. • It is a computer program designed to simulate an intelligent conversation with one or more human users via auditory or textual methods. • It is a computer program with artificial intelligence to talk to people through voices or typed words.

9. Computational linguistics is an interdisciplinary field. It takes input from different fields. Linguistics Mathematics Cognitive Science Computational Linguistics Philosophy Psychology Computer Science

10. Relation of CL to Other Disciplines • Artificial Intelligence (notions of representation, search) • Machine Learning (probabilistic or statistical techniques) • Human Computer Interaction (HCI) • Linguistics (Syntax, Semantics etc.) • Information Retrieval • Philosophy of language (formal logic) • Electrical Engineering (Optical Character Recognition) • Psychology (insight into learning of linguistic constructions)

11. Computational Linguisticsis closely related to… • Natural Language Technology • Natural Language Engineering • Natural Language Processing • Artificial Intelligence

12. Some Applications of Computational Linguistics • Spelling and Grammar Checkers • Screen readers for the blind • Machine readable Dictionaries • Machine Translation Systems • Question-Answering Systems • Information Retrieval • Information Extraction • Automatic Summarization

13. Example Application- Search Engine

14. Example Application- Spelling Checker

15. Example Application- Grammar Checker

16. Example Application- Question Answering

17. Example Application- Machine Translation

18. Careers for Computational linguists • Academia • Research and Higher education • Teaching in IT or English • Industry • Companies that work in fields like: speech technology, information extraction, machine translation, automatic summarization, etc. • Microsoft, Google, HP Labs, Xerox Research are some major companies developing language tools. • Information Technology departments of Banks • Web designing that needs language and computer knowledge

19. Likely jobs for Computational linguists • Software Engineers • Researchers in Machine Translation • Teachers of Computer Science/Linguistics in schools • Linguistic database analyzers • Designers of mono/bi-lingual dictionaries • Speech technologists • Teaching or Research Assistants

20. Getting a job in language technology Best candidate has: • Advanced degree in linguistics • Coursework or major in computational linguistics or computer science • Knowledge of foreign language(s) • Computer scripting or programming skills • Work or internship in industry

21. Some companies that hire computational linguists • CL Research - tools for developing lexical databaseshttp://www.clres.com/ • Comverse - speech technology for computers and internethttp://www.comverse.com • Cycorphttp://www.cyc.com • IBM - dictation software for English and other languageshttp://www-4.ibm.com/software/speech/ • Language Intelligence - a linguistic software companyhttp://www.languageintelligence.com • Lingsoft - a linguistic software companyhttp://www.lingsoft.fi/ • Scansoft - speech recognition systemshttp://www.scansoft.com • Soliloquy - natural language understanding softwarehttp://www.soliloquy.com • Microsoft - software for dictation and text-to-speechhttp://www.microsoft.com

22. Exercise 1 • Write down what you have understood by ‘Computational Linguistics’? • Try the different applications mentioned and write down your observations. • Do you think the tools are useful to us? Submit your work before the next class.

23. Exercise 2 • Observe how the spelling and grammar checker on your pc works. Give 5 errors that were pointed out by each tool. • Practice giving the right keywords to search for a document using Google or Yahoo. Give the results. • Look for different chatbots, make a list of the urls, talk to them and judge which one is the best one. To Do Write down your observations and submit them as soon as you are done.

24. Assignment 1Due date: After 2 weeks Write short essays [minimum 8-10 sentences] on the following topics: • Spelling and grammar checkers • Your favorite search engine • You and a chatbot You have to include examples, urls, references, sample data etc. wherever necessary. Marks will be deducted if any kind of plagiarism is found.