Has anybody ever seen a situation where a couple of patterns such as
Fact( field >= 10 )
not Fact( field > 20 )
was appropriate? This does not match Facts where field isn't between 10 and 20, and so it would seem to be the same as
Fact( field >= 10 && <= 20 )
but actually it doesn't match any such Fact whenever any other Fact with field > 20 is around.