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C00002 00002	prevent[f85,jmc]		Priorities by prevention
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prevent[f85,jmc]		Priorities by prevention

Perhaps explicit nesting corresponds to common sense when one condition
prevents another from applying.  The example is

Object  A  being trivial prevents  on(A,B)  from preventing  B  from
being moved.

Here is a propositional version.

n(p) -- p is normally true

np(p,q) -- p  being true normally prevents  q  from being true, abbreviated
		p  normally prevents  q.

With this notation we can construct the expression

np(p,np(q,r))

which is read --- p  normally prevents  q  from preventing  r.

Example:  Suppose we have

n(r)

np(q,r)

np(p,np(q,r))

q

p

We ask about  r  and we want to  r  to come out true.  The question is
Can we get this result by minimizing something?  What?