COMMENT ⊗   VALID 00002 PAGES
C REC  PAGE   DESCRIPTION
C00001 00001
C00002 00002	featur[e81,jmc]		Features of situations
C00005 ENDMK
C⊗;
featur[e81,jmc]		Features of situations

	The idea is that a situation or problem should be described
additively in terms of its features.  An added feature may correspond
to a missing physical object.  Thus if we describe the missionaries
and cannibals problem, we may add the feature that the boat lacks
oars.  In fact the original form of M and C can be describe as a
collection of features.

	Perhaps addition of features shouldn't be regarded as commutative,
so that we begin with a basic situation and add features relative to
it, where relative means that the description of each new feature
depends for its meaning on what has been said previously.  Consider
M and C.

	1. Three missionaries and three cannibals come to a river.

	2. They find a boat that can carry two people but can be
rowed by one.

	3. If the cannibals ever outnumber the missionaries on either
bank the missionaries will be eaten.

	4. How shall they all cross the river safely?

	The reason for considering features additively is that each
added feature defeats a circumscription, i.e. complicates the problem.
If it weren't for the peculiar properties of the cannibals, the
solution would be simpler.  We want also to regard the first two statements
as features.  It might fit the formalism better if we began with the
problem described as

	1. The problem is to cross a river.

	2. There is a boat.

	3. Three missionaries and three cannibals are to croos.

	4. The boat seats two and can be rowed by one.

	5. If the cannibals ever outnumber the missionaries on either
bank the missionaries will be eaten.

1989 Sep 20 (of limited relevance)
It would be nice if when we omitted the feature that a boat requires a person
to guide it, we would then get the simpler solution of the boat going
back by itself.