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Introduction to AI & AI Principles (Semester 1) WEEK 4 (07/08)

Introduction to AI & AI Principles (Semester 1) WEEK 4 (07/08). John Barnden Professor of Artificial Intelligence School of Computer Science University of Birmingham, UK. Expert versus Everyday/Common-Sense (review). Expert AI: e.g., Expert systems for medical diagnosis, etc.

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Introduction to AI & AI Principles (Semester 1) WEEK 4 (07/08)

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  1. Introduction to AI &AI Principles (Semester 1)WEEK 4 (07/08) John Barnden Professor of Artificial Intelligence School of Computer Science University of Birmingham, UK

  2. Expert versus Everyday/Common-Sense(review) • Expert AI: e.g., • Expert systems for medical diagnosis, etc. • Chess programs • Mathematical theorem provers • Aircraft movement planning systems • Specialized manufacturing robots • Everyday/Common-Sense AI: e.g., • Language processing, for no specific domain • Common-sense reasoning about the everyday world • Seeing the everyday world

  3. WHY IS EVERYDAY AI CHALLENGING?

  4. (review) • Who … … ? • How many of you … … ? • How many students at the University own cats?

  5. Notice on van:CAUTIONCHILDREN • What could this mean?

  6. Some Possible Meanings (of the phrase in isolation, at least) • Be cautious, you might harm a child. • Be cautious, a child might harm you! • Children, be cautious. • Caution some children, please. • This locker (say) is for the children of the Caution family. • These are the children who have been cautioned. • These are the children who have done some cautioning. • These are the children who are “a caution.”

  7. at Birmingham airport EU Nationals this way Other passports this way

  8. Three Touching Tales • John got to his front door, but realized he didn’t have his key. • Mary went to a restaurant for lunch. Afterwards she didn’t have enough money to take a taxi. • Mary went to a restaurant for lunch. Afterwards she didn’t have enough money to buy the car she wanted.

  9. Some Lessons from the Above • Role of context: • co-text • discourse location, time & participants • characteristics of the environment, the participants, the entities talked about. • Role of extensive, diverse knowledge of the world. • Efficient, appropriate accessing of that knowledge. • Role of inference, to join things up. • Role of conjectured goals of the other participants in a conversation.

  10. Further Difficulties with Language, 1 • NL expressions can be syntactically ambiguous. • She hit the man with the telescope. • Does the prepositional phrase with the telescope “attach” to the man or to hit or to she?: • She [ hit [[the man] with [the telescope]] ]. • She [ [[hit [with the telescope]] [the man] ]. • [She with [the telescope]] hit [the man]. • What if the verb were “saw”?

  11. Another example of syntactic ambiguity. • I saw that gasoline can explode. • can: noun (N) or verb (V)? • that: complementizer(CZR) or demonstrative determiner (DD) ? • I saw [ [that(DD) [gasoline can(N)]] explode ]. • I saw [that(CZR) [gasoline can(V) explode]].

  12. Further Difficulties with Language, 2 • Lexical ambiguity:Words often have a range of distinct meanings, possibly without varying the part of speech (noun, verb, or whatever).  • ball, newspaper, bank, mole, sloth, ...  • The different meanings may or may not be related to each other. • When they are: POLYSEMY.   • When they’re not: HOMONYMY.

  13. Further Difficulties with Language, 3 • Words can be vague in their meaning.  • several, recently, thousands, tall, air, book[as noun],chair, think, work [as verb or noun], ...

  14. Further Difficulties with Language, 4 • Some words, such as pronouns and demonstrative determiners, are intrinsically contextual in their reference or other effects.  • I,she, everyone, every, that[pronoun or determiner],the, then, today, here, and so forth.

  15. Further Difficulties with Language, 5 • Pronouns are anaphoric. But there are types of anaphor other than by pronouns, and they can get very implicit: • When John got home, he found he’d lost his key. • Probably the key to his front door. He may have many other keys. • John dropped the teapot. The handle broke. • What handle? None explicitly mentioned.  • John went to clear the windscreen, but the de-icer can was empty. • Clearing a windscreen doesn’t have to involve a de-icer can at all – the phrase the de-icer is TELLING you that some de-icer was used in the clearing as well as then REFERRING to it. 

  16. Further Difficulties with Language, 6 • What look like definite references may actually be indefinite or general, or may fail to refer to anything at all, or may be incorrect.  • Susan’s brother is helping her. • This is OK even if Susan has several brothers, at least in suitable contexts. • The dog is an intelligent mammal. • This would often/normally be a statement about dogs in general. • The square root of minus one doesn’t exist. • The man in the corner actually turned out to be a woman.

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