Download Artificial Intelligence

Artificial Intelligence:
Introduction
Course Instructors:
Dr. Mehnaz Adnan
Ms. Huma Rizvi
Ms. Moona Kanwal
Mr. Raza Hassan
What is intelligence?
• Intelligence is the computational part of
the ability to achieve goals in the world.
• Varying kinds and degrees of intelligence
occur in people, many animals and some
machines.
What is Artificial Intelligence?
• 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.
What is AI?
Views of AI fall into four categories:
Thinking humanly Thinking rationally
Acting humanly Acting rationally
The textbook advocates "acting rationally"
Acting humanly: Turing Test
• Turing (1950) "Computing machinery and intelligence":
• "Can machines think?"  "Can machines behave intelligently?"
• Operational test for intelligent behavior: the Imitation Game
• Predicted that by 2000, a machine might have a 30% chance of
fooling a lay person for 5 minutes
• Anticipated all major arguments against AI in following 50 years
• Suggested major components of AI: knowledge, reasoning,
language understanding, learning
Intelligence
• Turing Test: A human communicates
with a computer via a teletype. If the
human can’t tell he is talking to a
computer or another human, it passes.
– Natural language processing
– knowledge representation
– automated reasoning
– machine learning
• Add vision and robotics to get the total
Turing test.
Thinking humanly: cognitive
modeling
• 1960s "cognitive revolution": informationprocessing psychology
• Requires scientific theories of internal activities
of the brain
• -- How to validate? Requires
1) 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 AI
Acting rationally: rational agent
• Rational behavior: doing the right thing
• The right thing: that which is expected to
maximize goal achievement, given the
available information
• Doesn't necessarily involve thinking – e.g.,
blinking reflex – but thinking should be in
the service of rational action
Thinking rationally: "laws of thought"
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Aristotle: what are correct arguments/thought
processes?
Several Greek schools developed various forms of
logic: notation and rules of derivation for thoughts; may
or may not have proceeded to the idea of
mechanization
Direct line through mathematics and philosophy to
modern AI
Problems:
1.
2.
Not all intelligent behavior is mediated by logical deliberation
What is the purpose of thinking? What thoughts should I have?
Is this machine intelligent or not?''?
• Is intelligence a single thing so that one
can ask a yes or no question ``Is this
machine intelligent or not?''?
Is this machine intelligent or not?''?
• No. Intelligence involves mechanisms, and AI
research has discovered how to make
computers carry out some of them and not
others.
• If doing a task requires only mechanisms that
are well understood today, computer programs
can give very impressive performances on these
tasks. Such programs should be considered
``somewhat intelligent''.
Isn't AI about simulating human
intelligence?
• Sometimes but not always or even usually.
• On the one hand, we can learn something
about how to make machines solve
problems by observing other people or just
by observing our own methods.
Isn't AI about simulating human
intelligence?
• On the other hand, most work in AI
involves studying the problems the world
presents to intelligence rather than
studying people or animals.
• AI researchers are free to use methods
that are not observed in people or that
involve much more computing than people
can do.
What about IQ? Do computer
programs have IQs?
• No. IQ is based on the rates at which
intelligence develops in children.
• It is the ratio of the age at which a child
normally makes a certain score to the
child's age. The scale is extended to
adults in a suitable way.
What about IQ? Do computer
programs have IQs?
• IQ correlates well with various measures of
success or failure in life, but making computers
that can score high on IQ tests would be weakly
correlated with their usefulness.
• For example, the ability of a child to repeat back
a long sequence of digits correlates well with
other intellectual abilities, perhaps because it
measures how much information the child can
compute with at once. However, ``digit span'' is
trivial for even extremely limited computers.
What about other comparisons
between human and computer
intelligence?
• Arthur R. Jensen [Jen98], a leading researcher
in human intelligence, suggests ``as a heuristic
hypothesis''
• that all normal humans have the same
intellectual mechanisms and that differences in
intelligence are related to ``quantitative
biochemical and physiological conditions''. I see
them as speed, short term memory, and the
ability to form accurate and retrievable long term
memories.
• Whether or not Jensen is right about
human intelligence, the situation in AI
today is the reverse
Does AI aim to put the human mind
into the computer?
• Some researchers say they have that
objective, but maybe they are using the
phrase metaphorically. The human mind
has a lot of peculiarities, and I'm not sure
anyone is serious about imitating all of
them
• Replacing the brain
Does AI aim at human-level
intelligence?
• Yes. The ultimate effort is to make
computer programs that can solve
problems and achieve goals in the world
as well as humans. However, many
people involved in particular research
areas are much less ambitious.
How far is AI from reaching humanlevel intelligence? When will it
happen?
• 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.
How far is AI from reaching humanlevel intelligence? When will it
happen?
• However, most AI researchers believe that
new fundamental ideas are required, and
therefore it cannot be predicted when
human level intelligence will be achieved.
• Our best systems have the intelligence of
a frog
• Mind you, how many frogs spend all their
intelligence controlling a nuclear power
plant?
Are computers the right kind of
machine to be made intelligent?
• Computers can be programmed to
simulate any kind of machine
Are computers fast enough to be
intelligent?
• Some people think much faster computers
are required as well as new ideas.
• Computers of 30 years ago were fast
enough if only we knew how to program
them. Of course, quite apart from the
ambitions of AI researchers, computers
will keep getting faster.
What about parallel machines?
• Machines with many processors are much
faster than single processors can be.
Parallelism itself presents no advantages,
and parallel machines are somewhat
awkward to program. When extreme
speed is required, it is necessary to face
this awkwardness.
What about making a ``child
machine'' that could improve by
reading and by learning from
experience?
• This idea has been proposed many times,
starting in the 1940s. Eventually, it will be
made to work.
What about making a ``child
machine'' that could improve by
reading and by learning from
experience?
• However, AI programs haven't yet reached
the level of being able to learn much of
what a child learns from physical
experience. Nor do present programs
understand language well enough to learn
much by reading
Philosophical foundation
• Logic,
• methods of reasoning,
• mind as physical system foundations of
learning,
• language,
• rationality
Weak and Strong AI Claims
• Weak AI:
– Machines can be made to act as if they were
intelligent.
• Strong AI:
– Machines that act intelligently have real,
conscious minds.
Weak AI :Can machine act
intelligently
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May be :pass turning test
Can machine think?
Answer: ill-defined
Why?
– Consider following
– Can machine fly?
– Can machine swim?
• The argument from disability
– Machine can never do X
• The argument from informality
– Human brain is too complex
Strong AI :Can machine really think
• Running sufficient program or knowing the
right outputs is not sufficient condition for
being a mind
• Chinese Room hypothesis by John Searle
• The Chinese Room
?
!
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AI prehistory
• Philosophy
• Mathematics
• Economics
• Neuroscience
• Psychology
• Computer
engineering
• Control theory
• Linguistics
Logic, methods of reasoning, mind as physical
system foundations of learning, language,
rationality
Formal representation and proof algorithms,
computation, (un)decidability, (in)tractability,
probability
utility, decision theory
physical substrate for mental activity
phenomena of perception and motor control,
experimental techniques
building fast computers
design systems that maximize an objective
function over time
knowledge representation, grammar
Abridged history of AI
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1943
1950
1956
1952—69
1950s
• 1965
• 1966—73
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1969—79
1980-1986-1987-1995--
McCulloch & Pitts: Boolean circuit model of brain
Turing's "Computing Machinery and Intelligence"
Dartmouth meeting: "Artificial Intelligence" adopted
Look, Ma, no hands!
Early AI programs, including Samuel's checkers
program, Newell & Simon's Logic Theorist,
Gelernter's Geometry Engine
Robinson's complete algorithm for logical reasoning
AI discovers computational complexity
Neural network research almost disappears
Early development of knowledge-based systems
AI becomes an industry
Neural networks return to popularity
AI becomes a science
The emergence of intelligent agents
State of the art
• 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
Branches of AI
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Learning
Rule-Based Systems
logic
Search
Planning
Ability-Based Areas
Robotics
Agents
Branches of AI
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pattern recognition
Ontology
heuristics
genetic programming
Applications of AI
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game playing
speech recognition
understanding natural language
computer vision
expert systems
heuristic classification