Robotics Reference
In-Depth Information
automation of reasoning in the solution of commonsense problems. This
wasadreamofJohnMcCarthyintheearlydaysofAI.
The Advice Taker
McCarthy's 1959 paper, “Programs with Common Sense”, presented an
intriguing view of how computer programs might be made to think like
human beings. The simplest program proposed by McCarthy was called
the Advice Taker,
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and was based on the idea of drawing immediate
conclusions from a list of premises. The Advice Taker was a method
proposed for solving problems by manipulating sentences in formal lan-
guages, such as the language of logic described above. And the Advice
Taker was unusual, for those days, in that it allowed the user to improve
the program's performance “in real time” (i.e., while it was working on a
problem) by giving it advice in the form of true statements that it might
find useful. McCarthy's idea was that, when it received a piece of advice,
the program would already have generated several new and true state-
ments from those with which it started the problem solving process. By
adding a new piece of advice, the user would encourage the program to
combine this new statement with each of the other true statements it
already had in its memory, thereby allowing it to create even more true
statements. It might at first appear that encouraging the program to grow
its “tree” of true statements in this way would lead to it running out of
memory space or time. But the fact that a human was providing the
new advice would mean that the human would, in effect, be guiding the
program towards a solution.
The ultimate objective of the Advice Taker project was to make pro-
grams that learn from their experience as effectively as humans do. In
McCarthy's opinion, a system that is to evolve intelligence akin to that
of humans should have at least the following features:
1. It must be possible to represent all behaviours of the system in the
language of the system.
2. Interesting changes in behaviour must be expressible in a simple
way.
3. All aspects of behaviour except the most routine must be improv-
able. In particular, the improving mechanism should itself be im-
provable.
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The Advice Taker was a program concept. It was never actually written.
