So what is AI?

What is AI?

Views of AI fall into four categories:

Thinking humanly Thinking rationally

Acting humanly Acting rationally

The textbook advocates "acting rationally"

State of the art: Game playing

State of the art: Robots

• http://robots.stanford.edu/movies/minerva.mpg

State of the art: NASA’s Rover on Mars

• http://www.youtube.com/watch?v=Pb8riJ_mmio&feature=related

• http://www.youtube.com/watch?v=UyM1bgKWzng&feature=related

State of the art: DARPA’s Urban Challenge

• http://www.youtube.com/watch?v=GmERrJXhoUQ

• http://www.youtube.com/watch?v=RI4JopnCrZI

What is AI?

Views of AI fall into four categories:

Thinking humanly Thinking rationally

Acting humanly Acting rationally

The textbook advocates "acting rationally"

Why do we need AI?

• Computer vs. Human– Strength & Weakness

Thinking humanly: cognitive modeling

• Understand how human brains work

• Requires scientific theories of internal activities of the brain

• Now distinct from AI– Called cognitive science

• Human intelligence depends on unconscious instinct rather than conscious symbolic logic

Acting Humanly: Turing Test

• Turing (1950) "Computing machinery and intelligence":• "Can machines think?" "Can machines behave

intelligently?"

• Suggested major components of AI: language understanding, knowledge, reasoning, learning

• Nobody is really designing a “Turing Test Machine”

•

Captcha!• http://www.youtube.com/watch?v=Aszl5avDtek

Thinking rationally: "laws of thought"

• Study the right ways of thinking: logic

• Several Greek schools developed various forms of logic: notation and rules of derivation for thoughts

• Program exists that can in principle solve any logical problem

• Problems: 1. Not all intelligent behavior is mediated by logical deliberation2. The knowledge is not 100% certain3. Solve a problem “in principle” is not enough!

But can machines really think?

• Can machines really think like a human?– The Chinese Room argument

Acting rationally: rational agent

• Rational behavior: doing the right thing– without proving it is the best thing to do

• The right thing: which is expected to maximize goal achievement, given the available information

• Doesn't necessarily involve thinking, but thinking should be in the service of rational action

How about Savage vs. Human?

Humanly vs. Rationally

• Humanly:– Empirical science– Involves hypothesis and experimentation

• Rationally– Mathematics (thinking)– Engineering (acting)

A brief history of AI• Dartmouth conference (1956)• Large amount of research in the 60s

– Simple problem solver, logic theorem prover, – People got over-optimistic of AI

• First AI winter (70s)• First Revival (80s)

– Expert system, billion $$$ business

• Second AI winter (85-90s)• Second revival (90s – now)

– Increasing computing power, multi-disciplinary approach, mathematical methods, focus on sub-problems

Achievements of AI

• Deep Blue defeated the reigning world chess champion Garry Kasparov in 1997

• Proved a mathematical conjecture (Robbins conjecture) unsolved for decades

• No hands across America (driving autonomously 98% of the time from Pittsburgh to San Diego)

• During the 1991 Gulf War, US forces deployed an AI logistics planning and scheduling program that involved up to 50,000 vehicles, cargo, and people

• NASA's on-board autonomous planning program controlled the scheduling of operations for a spacecraft

• Proverb solves crossword puzzles better than most humans

Tasks of AI

• Reasoning– Solve puzzles, play games, prove theorems– Different from human solvers– Facing resource limitations (time and space)

• Knowledge representation– How to represent intuitions

• Planning• Learning: unsupervised, supervised, reinforced• Natural language processing• Vision

Course overview

• Introduction (chapters 1,2)

• Problem solving (chapter 3-5)

• Game playing (chapter 6)

• Representation and reasoning (chapters 7-10)

• Planning (chapters 11-12)

• Probabilistic reasoning and learning (chapters 13-17)