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C00002 00002	mcderm[w85,jmc]		Notes on McDermott's "Planning routes through uncertain territory
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mcderm[w85,jmc]		Notes on McDermott's "Planning routes through uncertain territory
McDermott, Drew and Ernest Davis (1984): ``Planning Routes through
Uncertain Territory'', Artificial Intelligence, volume 22, Number 2, March 1984.

Their system seems too elaborate to me.  How about the following system.

1. Objects are given co-ordinates, and these co-ordinates are
expressed as sentences in a database along with any other sentences
that may be used.  Typical sentences are

(= (latitude x) (+ Mt.-Diablo-latitude (miles -10.7)))

(= Mt.-Diablo-latitude (degrees (precision 0.01 37.412)))

2. Note that we use expressions for latitudes.  We give numbers
rather than ranges, but there is a convention that numbers are
good to 20 percent unless otherwise stated.  When a distance
is known with a different error from a direction, we allow
polar co-ordinates.  Thus we can have

(= (latitude Tracy) (+ Mt.-Diablo-latitude (* (miles 15) (cos theta1))))

(= (theta1 (degrees (precision 50 120))))