LING 388: Language and Computers Sandiway Fong Lecture 1: 8/23

Administrivia Where –Harvill 208 When –MW 3:45-5:00PM –Monday September 6th (no class: labor day) –Wednesday September 29th (no class) Office Hours –MW 5:00-6:00PM(after class) –Other times by appointment –Location: Douglass 308 (Linguistics)

Administrivia Map –Classroom (Harvill) –Office (Douglass)

Administrivia Homepage: – Lecture powerpoint slides: –available on homepage after each class –in both ppt and Adobe PDF formats –Last year’s slides also available online caution: there will be changes from last year

Administrivia Tips on how to take this class –No required textbook save time suggested readings on request –Lecture slides contain everything you need to know in order to do the homeworks To understand the slides, you need to attend classes to “grok” the concepts –Unclear on something? You are encouraged to ask questions in or after class Ask while the question is still fresh in your mind –Have an idea, want to go over some of the material again, or have more in-depth questions? Office hours Make an appointment

Administrivia Course Objectives –Theoretical Introduction to natural language processing techniques –Practical Be able to write a natural language grammar that runs on a computer Get an idea of what’s hard and what’s easy to do on a computer

Administrivia Laboratory Exercises –Some lectures will be laboratory sessions –50/50 lecture/exercises on the computer in class –Homework questions will be handed out in these sessions –Homework questions are designed to continue the lab exercises –You may do the homework exercises on your own computer or at the computer laboratory

Administrivia Grading –4~5 homeworks + 1 final “take-home” exam –Each homework worth about 8-12 points –Homeworks are due 1 week from the date (at midnight) they are handed out –Homeworks must be submitted by –Final exam will be worth around 35 points –You may discuss the homeworks with your classmates –However, you must do the work and write them up independently

Administrivia Homework tips –Homeworks are based on lab exercises make sure you show up for the lab lectures –Possible time-saving strategy: Stay on after the lecture and do the homework questions right there exercises are fresh in your mind may even be possible to complete the homework in an hour right there … –Nightmare strategy: Wait until the evening homework is due, scratch your head over the lecture notes, have tons of questions and start panicking your computer crashes, the net goes down …

Administrivia Late Policy –All homeworks are mandatory –50% deduction if handed in late –10% if not handed in when the next homework is out –You must schedule a meeting with me and explain Upcoming Emergencies –Must let me know ahead of time or as soon as you can –Explanation needed

Administrivia Homework Disaster Policy –You “tank” on a homework do badly or way worse than you expected Schedule a meeting –What are your options? 1: there are always extra credit questions to bump your score back up –Chances to demonstrate you really knew the material well 2: final exam will re-test you on the areas covered –2nd chance –Philosophy You are not penalized for learning or making an unfortunate mistake

Administrivia Fill out form to be passed out –Name – –Year –Major –Why are you interested in computers and language? –Relevant background

Natural Language Processing Computational Linguistics Question: –How to process natural languages on a computer Intersects with: –Computer science (CS) –Mathematics/Statistics –Artificial intelligence (AI) –Linguistic Theory –Psychology: Psycholinguistics e.g. the human sentence processor

Natural Language Properties Which ones are going to be difficult for computers to deal with? Grammar (Rules for putting words together into sentences) –How many rules are there? 100, 1000, 10000, more … –Portions learnt or innate –Do we have all the rules written down somewhere? Lexicon (Dictionary) –How many words do we need to know? 1000, 10000, …

Computers vs. Humans Knowledge of language –Computers are way faster than humans They kill us at arithmetic and chess –But human beings are so good at language, we often take our ability for granted Processed without conscious thought Do pretty complex things

Examples Knowledge –Which report did you file without reading? –(Parasitic gap sentence)

Examples Changes in interpretation John is too stubborn to talk to John is too stubborn to talk to Bill

Examples Ambiguity –Where can I see the bus stop? –stop: verb or part of the noun-noun compound bus stop –Context (Discourse or situation)

Examples Ungrammaticality –*Which book did you file the report without reading? –* = ungrammatical relative –ungrammatical vs. incomprehensible

Example The human parser has quirks Ian told the man that he hired a story Ian told the man that he hired a secretary Garden-pathing Temporary ambiguity tell: someone something vs. …

Examples More subtle differences The reporter who the senator attacked admitted the error The reporter who attacked the senator admitted the error –Processing time –Subject vs. object relative clauses –Q: Do we want to mimic the human parser completely?

Topics we will cover [From last year’s homepage, there will be changes.]

Next time … We will begin by gently introducing you to a programming language you will become familiar with –Two lectures –Name: PROLOG –Variant: SWI-PROLOG (free software) –Download: –Based on logic –“Natural” and easy to learn but powerful –Contains lots of nifty built-in features for writing grammars language was originally designed for this purpose