AI - Introduction
Bertil Ekdahl
[email protected]
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What is AI?
It is the science and engineering
of making intelligent machines,
especially intelligent computer
programs. It is related to the
similar task of using computers
to understand human intelligence,
but AI does not have to confine
itself to methods that are biologically
observable.
John McCarthy, http://www-formal.stanford.edu/jmc/whatisai/
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When did it start?
• Alan Turing
– 1947 lecture on intelligent machines.
– 1950 article: Computing Machinery and
Intelligence.
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The Turing Test
(Borrowed from Ola Flygt.)
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A Turing Machine
Penrose, Roger, “The Emperor’s New Mind”
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Two symbols B,1 where B means “blank” and 1 is
the tally symbol.
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ENIAC
(Electronic Numerical Integrator And Calculator)
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EDVAC
(Electronic
Discrete
Variable
Automatic
Computer)
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Dartmouth Artificial Intelligence (AI)
Conference
• We propose that a 2 month, 10 man study of artificial
intelligence be carried out during the summer of 1956 at
Dartmouth College in Hanover, New Hampshire.
• The study is to proceed on the basis of the conjecture
that every aspect of learning or any other
feature of intelligence can in principle be
so precisely described that a machine can
be made to simulate it. An attempt will be made
to find how to make machines use language, form
abstractions and concepts, solve kinds of problems
now reserved for humans, and improve themselves.
• Dartmouth AI Project proposal: J. McCarthy et al.; Aug.
31, 1955.
(http://www-formal.stanford.edu/jmc/history/dartmouth.html)
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Why such a conjecture?
… every aspect of learning […] be so
precisely described that a machine
can be made to simulate it.
Tabula rasa
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But the human intellect, which is the lowest in
the order of intellects and the most removed
from the perfection of the Divine intellect, is in
potency with regard to things intelligible, and
is at first "like a clean tablet on which
nothing is written", as the Philosopher
[Aristotle] says.
(Thomas Aquinas, Summa Theologica 1.79.2, 1265 - 1274)
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Connectionism
Rumelhart & McClelland: generic
associationist networks, subjected
to massive amounts of training, could
explain all of cognition.
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A problem
Rumelhart & McClelland was left with the
answer: Why is people smarter than rats?
Answer: [The] question does seem a bit
puzzling. […] another aspect to the difference
[…] is that the human environment includes
other people and the CULTURAL devices that
they have developed to organize their thinking
process.
(1986)
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Why such a conjecture?
…make machines use language, form
abstractions and concepts …
No difference between formal language
(programming language) and natural
language?
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Everything is a question of
representation?
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Roman digits
XV
III
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Binary digits
1111
11
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7654983274 36
2
1...100100
10
shift out
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Time
2h 30min 15s + 3h 45min 37s =?
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Fifty-five
Femtiofem
Fünfundfünfzig
Femoghalvtreds
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What is a Knowledge
Representation?
• A KR is a Surrogate
• A KR is a Set of Ontological Commitments
• A KR is a Fragmentary Theory Of Intelligent
Reasoning
• A KR is a Medium for Efficient Computation
• A KR is a Medium of Human Expression
(R. Davis, H. Shrobe, and P. Szolovits. What is a Knowledge Representation? AI Magazine, 14(1):17-33, 1993).
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Knowledge representation in AI
•
•
•
•
•
Logic
Semantic nets
Conceptual graphs
Neural nets
Object oriented methods
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Logic
Production system: IF … THEN
IF
you have pain in your back
AND you have eaten many Panocode
THEN examine your bile.
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Pain in your back?
Eaten
Yes
Panocode?
No
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G: Men are all alike.
P: IN WHAT WAY?
G: They’re always bugging us about something or other.
P: CAN YOU THINK OF A SPECIFIC EXAMPLE?
G: Well, my boyfriend made me come here.
P: YOUR BOYFRIEND MADE YOU COME HERE?
G: He says I’m depressed much of the time.
P: I AM SORRY TO HERE THAT YOU ARE DEPRESSED.
G: It’s true. I am unhappy.
P: DO YOU THINK COMING HERE WILL HELP YOU NOT
TO BE UNHAPPY?
G: I need some help, that much seems certain.
P: WHAT WOULD IT MEAN TO YOU IF YOU GOT SOME
HELP?
G: Perhaps I could learn to get along with my mother.
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P: TELL ME MORE ABOUT YOUR FAMILY.
(I remember X) ---> (Why do you remember X just now?)
Person: I remember my mother.
ELIZA: Why do you remember your mother just now?
(My {family-member} Y me) ---> (Who else in your family Y you?)
Person: My father hates me.
ELIZA: Who else in your family hates you?
Rules without left hand side.
ELIZA: Can you elaborate on that for me?, or
ELIZA: That is very interesting. Why do you say that?26
Logic goes beyond IF … THEN-rules
The author of the Iliad wrote the Odyssey; therefore
someone wrote both the Iliad and the Odyssey.
No one admires anyone who admires everyone who
admires someone.
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Semantic nets
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Cat
has
Fur
Vertebra
isa
has
has
Animal
isa
Mammal
Bear
isa
Whale
isa
lives in
Fish
lives in
Water
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Pacifist
isa
isa
Republican
Quaker
isa
isa
Nixon
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Conceptual Graph
CG: John is going to Boston by bus.
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/* schema facts */
man::person.
woman::person.
person[hasFather=>man].
person[hasMother=>woman].
Object method
/* facts */
abraham:man.
sarah:woman.
isaac:man[hasFather->abraham; hasMother->sarah].
/* rules consisting of a rule head and a rule body */
FORALL X,Y X[hasSon->>Y] <- Y:man[hasFather->X].
/* query */
FORALL X,Y <- X:woman[hasSon->>Y[hasHasFather->abraham]].
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Q. How far is AI from reaching human-level intelligence?
When will it happen?
A. A few people think that human-level intelligence can be
achieved by writing large numbers of programs of the kind
people are now writing and assembling vast knowledge
bases of facts in the languages now used for expressing
knowledge.
However, most AI researchers believe that new
fundamental ideas are required, and therefore it cannot be
predicted when human level intelligence will be achieved.
(John McCarthy, http://www-formal.stanford.edu/jmc/whatisai/)
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Why have we made limited progress
in AI? Because we haven't developed
sophisticated models of thinking, we
need better programming languages
and architectures, and we haven't
focused on common sense problems
that every normal child can solve.
(Minsky, 2002)
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What’s the problem?
Semantics
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Roman: LV
Binary: 110111
Octal:
Fifty-five
Femtiofem
Fünfundfünfzig
Femoghalvtreds
101101
Decimal: 55
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Susan saw the man in the park with a dog.
Susan saw the man in the park with a statue.
Susan saw the man in the park with a telescope
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Computer versus Common Sense
http://video.google.com/videoplay?docid=-7704388615049492068
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END
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AI - Introduction