Artificial IntelligenceChapter 1Chapter 1 1Outline♦ What is AI?♦ A brief history♦ The state of the artChapter 1 2What is AI?Systems that think like humans Systems that think rationallySystems that act like humans Systems that act rationallyChapter 1 3Acting humanly: The Turing testTuring (1950) “Computing machinery and intelligence”:♦ “Can machines think?” −→ “Can machines behave intelligently?”♦ Operational test for intelligent behavior: theImitation GameAI SYSTEMHUMAN? HUMANINTERROGATOR♦ Predicted that by 2000, a machine might have a 30% chance offooling a lay person for 5 minutes♦ Anticipated all major arguments against AI in following 50 years♦ Suggested major components of AI: knowledge, reasoning, languageunderstanding, learningProblem: Turing test is notreproducible, constructive, oramenable to mathematical analysisChapter 1 4Thinking humanly: Cognitive Science1960s “cognitive revolution”: information-processing psychology replacedprevailing orthodoxy ofbehaviorismRequires scientific theories of internal activities of the brain– What level of abstraction? “Knowledge” or “circuits”?– How to validate? Requires1) Predicting and testing behavior of human subjects (top-down)or 2) Direct identification from neurological data (bottom-up)Both approaches (roughly,Cognitive Science and Cognitive Neuroscience)are now distinct from AIBoth share with AI the following characteristic:the available theories do not explain (or engender)anything resembling human-level general intelligenceHence, all three fields share one principal direction!Chapter 1 5Thinking rationally: Laws of ThoughtNormative (or prescriptive) rather than descriptiveAristotle: what are correct arguments/thought processes?Several Greek schools developed various forms oflogic:notation and rules of derivation for thoughts;may or may not have proceeded to the idea of mechanizationDirect line through mathematics and philosophy to modern AIProblems:1) Not all intelligent behavior is mediated by logical deliberation2)What is the purpose of thinking? What thoughts should I haveout of all the thoughts (logical or otherwise) that Icould have?Chapter 1 6Acting rationallyRational behavior: doing the right thingThe right thing: that which is expected to maximize goal achievement,given the available informationDoesn’t necessarily involve thinking—e.g., blinking reflex—butthinking should be in the service of rational actionAristotle (Nicomachean Ethics):Every art and every inquiry, and similarly everyaction and pursuit, is thought to aim at some goodChapter 1 7Rational agentsAn agent is an entity that perceives and actsThis course is about designingrational agentsAbstractly, an agent is a function from percept histories to actions:f : P∗→ AFor any given class of environments and tasks, we seek theagent (or class of agents) with the best performanceCaveat:computational limitations makeperfect rationality unachievable→ design best program for given machine resourcesChapter 1 8AI prehistoryPhilosophy logic, methods of reasoningmind as physical systemfoundations of learning, language, rationalityMathematics formal representation and proofalgorithms, computation, (un)decidability, (in)tractabilityprobabilityPsychology adaptationphenomena of perception and motor controlexperimental techniques (psychophysics, etc.)Economics formal theory of rational decisionsLinguistics knowledge representationgrammarNeuroscience plastic physical substrate for mental activityControl theory homeostatic systems, stabilitysimple optimal agent designsChapter 1 9Potted history of AI1943 McCulloch & Pitts: Boolean circuit model of brain1950 Turing’s “Computing Machinery and Intelligence”1952–69 Look, Ma, no hands!1950s Early AI programs, including Samuel’s checkers program,Newell & Simon’s Logic Theorist, Gelernter’s Geometry Engine1956 Dartmouth meeting: “Artificial Intelligence” adopted1965 Robinson’s complete algorithm for logical reasoning1966–74 AI discovers computational complexityNeural network research almost disappears1969–79 Early development of knowledge-based systems1980–88 Expert systems industry booms1988–93 Expert systems industry busts: “AI Winter”1985–95 Neural networks return to popularity1988– Resurgence of probability; general increase in technical depth“Nouvelle AI”: ALife, GAs, soft computing1995– Agents, agents, everywhere . . .2003– Human-level AI back on the agendaChapter 1 10State of the artWhich of the following can be done at present?♦ Play a decent game of table tennisChapter 1 11State of the artWhich of the following can be done at present?♦Play a decent game of table tennis♦ Drive safely along a curving mountain roadChapter 1 12State of the artWhich of the following can be done at present?♦Play a decent game of table tennis♦ Drive safely along a curving mountain road♦ Drive safely along Telegraph AvenueChapter 1 13State of the artWhich of the following can be done at present?♦Play a decent game of table tennis♦ Drive safely along a curving mountain road♦ Drive safely along Telegraph Avenue♦ Buy a week’s worth of groceries on the webChapter 1 14State of the artWhich of the following can be done at present?♦Play a decent game of table tennis♦ Drive safely along a curving mountain road♦ Drive safely along Telegraph Avenue♦ Buy a week’s worth of groceries on the web♦ Buy a week’s worth of groceries at Berkeley BowlChapter 1 15State of the artWhich of the following can be done at present?♦Play a decent game of table tennis♦ Drive safely along a curving mountain road♦ Drive safely along Telegraph Avenue♦ Buy a week’s worth of groceries on the web♦ Buy a week’s worth of groceries at Berkeley Bowl♦ Play a decent game of bridgeChapter 1 16State of the artWhich of the following can be done at present?♦Play a decent game of table tennis♦ Drive safely along a curving mountain road♦ Drive safely along Telegraph Avenue♦ Buy a week’s worth of groceries on the web♦ Buy a week’s worth of groceries at Berkeley Bowl♦ Play a decent game of bridge♦ Discover and prove a new mathematical theoremChapter 1 17State of the artWhich of the following can be done at present?♦Play a decent game of table tennis♦ Drive safely along a curving mountain road♦ Drive safely along Telegraph Avenue♦ Buy a week’s worth of groceries on the web♦ Buy a week’s worth of groceries at