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Maybe projection isn't all Logic.

In AI projection can be done by running the progam, provided the complete state of the system is available, and the program describing the evolution of the system is available.

Suppose the neither a complete description of the situation nor a complete description of the process is available. Situation calculus ([McCarthy and Hayes, 1969]) was invented to deal with this by allowing logical inference from facts about a situation for which we do not have a complete description.

However, it is possible that humans do some projection by non-logical means, i.e. by running some mental process on a representation of the situation. If so, such mental simulation must use a greatly schematized representation of situations. The idea is to be able to answer a question, ``What will happen if tex2html_wrap_inline650 ?'' by mental simulation. A program could also use some kind of schematized simulation. Its output seems to be propositional. Subjectively, such simulations usually seem to be fragmentary.

John McCarthy
Mon Mar 2 16:21:50 PDT 1998