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Introduction to

NLP

What is Natural Language Processing?

Ques%on Answering: IBM’s Watson

• Won Jeopardy on February 16, 2011! 2 WILLIAM WILKINSON’S “AN ACCOUNT OF THE PRINCIPALITIES OF WALLACHIA AND MOLDOVIA” INSPIRED THIS AUTHOR’S MOST FAMOUS NOVEL Bram Stoker

Informa%on Extrac%on & Sen%ment Analysis

• nice and compact to carry!
• since the camera is small and light, I won't need to carry around those heavy, bulky professional cameras either!
• the camera feels flimsy, is plasIc and very light in weight you 4 have to be very delicate in the handling of this camera Size and weight AWributes: zoom affordability size and weight flash ease of use

Machine Transla%on

• Fully automaIc

5

• Helping human translators

Enter Source Text: TranslaIon from Stanford’s Phrasal : This is only a maWer of Ime.

Ambiguity makes NLP hard:

“Crash blossoms”

Violinist Linked to JAL Crash Blossoms Teacher Strikes Idle Kids Red Tape Holds Up New Bridges Hospitals Are Sued by 7 Foot Doctors Juvenile Court to Try ShooIng Defendant Local High School Dropouts Cut in Half

Ambiguity is pervasive

Fed raises interest rates New York Times headline (17 May 2000) Fed raises interest rates Fed raises interest rates 0.5%

non-­‐standard English Great job @jusInbieber! Were SOO PROUD of what youve accomplished! U taught us 2 #neversaynever & you yourself should never give up either segmenta%on issues (^) idioms dark horse get cold feet lose face throw in the towel neologisms unfriend Retweet bromance tricky en%ty names Where is A Bug’s Life playing … Let It Be was recorded … … a mutaIon on the for gene … world knowledge Mary and Sue are sisters. Mary and Sue are mothers. But that’s what makes it fun! the New York-­‐New Haven Railroad the New York-­‐New Haven Railroad

Why else is natural language

understanding difficult?

Making progress on this problem…

• The task is difficult! What tools do we need?
  • Knowledge about language
  • Knowledge about the world
  • A way to combine knowledge sources
• How we generally do this:
  • probabilisIc models built from language data
    • P(“maison” → “house”) high
    • P(“L’avocat général” → “the general avocado”) low
  • Luckily, rough text features can oven do half the job.

Skills you’ll need

• Simple linear algebra (vectors, matrices)

• Basic probability theory

• Java or Python programming

• Weekly programming assignments

Introduction to

NLP

What is Natural Language Processing?