Intelligent Systems Lecture Notes

9 September 2011 • What are Intelligent Systems?

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Outline

• What are intelligent systems?
• Intelligent structure.
• Science vs engineering.

What are Intelligent Systems?

• Who knows?
  • Answering this question has been a long-term, and on-going, task.
  • There are many answers, depending on your point of view.
• Does it really matter?
  • Ultimately, no — but let’s stick with it for a while.

What is Intelligence?

• Let’s ignore “systems” and look at “intelligent.”
• Is a calculator intelligent?
• Is a word processor intelligent?
  • But it can check my spelling.
• Is a Roomba intelligent?
• Is Google search intelligent?
  • Is Wolfram Alpha intelligent?

Intelligence

• Intelligence based on both process and outcome.
  • The process should be significant in some sense.
  • The outcome should be reasonable with expectations.
• Process and outcome can be further qualified.
  • Process can be open-ended, capable of handling unexpected input.
  • Outcome can be optimal.

Intelligence as Computation

• Outcome is a result of computation.
• Intelligence is computation organized to produce particular outcomes.
  • We know computations.
• This is a controversial point of view (deep AI).
  • But it replaces a vexing issue with a comfortable one.

A Computation

what color is(x)
  switch x 
    case "snow" : return "white"
    case "grass": return "green"
    case "sky"  : return "blue"
    default     : return "don't know"

what color is("snow") → "white"
what color is ("mud") → "don't know"

Another Computation

what color is(x)
  if is color(x, y) return y

what color is(x)
  if is made of(x, y) and is color(y, z)
    return z

what color is(x)
  return "don't know"

is color("snow", "white")
is made of("grass", "vegetation")
is color("vegetation", "green")

what color is("snow") → "white"
what color is("grass") → "green"
what color is ("mud") → "don't know"

Intelligent Computations

• How do these two computations differ?
  • Which one is the more “intelligent” computation?
  • They’re both the same with respect to outcomes.
• Is the strange second computation more intelligent than the first computation?
  • Hint: why is grass green?

Intelligent Computation

• The second computation has a particular structure:
  • It has a set of facts arranged as a knowledge base.

    is color("snow", "white")
    

  • It has a general (and strange) computational action (reasoning rules).

    what color is(x)
      if is made of(x, y) and is color(y, z)
        return z
    

Structural Intelligence

• An intelligent computation has a particular structure:
  • A collection of facts (the data structure)
    • And a representation for those facts.
  • A set of reasoning rules for dealing with facts (the algorithm).
• This intelligent structure then produces intelligent outcomes.

Oh Really?

• Isn’t this just all a bunch of smoke and mirrors?
  • Can’t you write regularly structured programs to do the same thing?
• You can, but
  • Writing the regular program is hard without understanding the intelligent program.
  • Providing equivalent generality is hard and expensive.
  • Machine translation is the classic example.

Science v Engineering

• The difference between science and engineering captures the difference nicely.
  • Artificial intelligence is science.
  • Intelligent systems is engineering.
  • Regular programs are technology.
• This is an engineering course.
  • The translation to technology is an optimization.

Summary

• Intelligence is a particular computational structure.
  • The structure produces intelligent outcomes.
• The structure relies on special data structures, knowledge bases, and algorithms, reasoning rules.
  • Varying data structures and algorithms produce varying structures.

References

• Introduction (Chapter 1) of Knowledge Representation and Reasoning by Ronald Brachman and Hector Levesque from Morgan Kaufmann, 2004.
• The Sciences of the Artificial, 3rd edition, by Herbert Simon from MIT Press, 1996.
• Gödel, Escher, Bach, 20th anniversary edition, by Douglas Hofstadter from Basic Books, 1999.

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This page last modified on 2011 September 9.