...jmc@cs.stanford.edu

Work partly supported by ARPA (ONR) grant N00014-94-1-0775 and partly done while the author was Meyerhoff Visiting Professor at the Weizmann Institute of Science, Rehovot, Israel

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...

This document is reachable from the WWW page http://www-formal.stanford.edu/jmc/home.html.

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...``models''

Biologists speak of a fruitfly or mouse model of a biological phenomenon. Here we can speak of a lemmings model of scene parsing, etc.

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...AI.

Alas, there is in 1994 good reason to write about the importance of basic research models ``like a missionary talking to cannibals rather than with a decent terseness and restraint'', to use the words of G. H. Hardy [Hardy, 1937].

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...He

The pronoun ``he'' embraces women, men and robots.

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...walkers.

Within regions the horizontal location of a position may be important. For example, it usually matters where a bridge is started within a region. I remember positions by irregularities in color or relief. Should we be purist and require this of programs, or should we let them use co-ordinates?

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