perm filename CLOSED[S80,JMC] blob sn#523206 filedate 1980-07-18 generic text, type T, neo UTF8
CLOSED WORLD ASSUMPTIONS

	It seems to me that Reiter (1978) overdoes the advantages in
compactness of the closed world assumption.  My intuition is that it
has other advantages, but I'm not sure what they are.

	Suppose we want to list a set ⊗A exhaustively.  We then write

	%2∀x.(x ε A ≡ x = a ∨ x = b ∨ x = c) ∧ card A = 3%1.

	We should list the set of flights of Air Canada (to use
Reiter's example) by listing an abstract set ⊗A as above and then
asserting the identity of the set of flights with ⊗A. 

	In this way we can get the compactness of the closed world
assumption without assuming that we know all, since we can put some
qualification on the assertion that qA is precisely the set of
Air Canada flight.