context: It is unlikely that Greg is gray. It is probably not the case that Lily is a lion. Chances are about even that Sandra took the milk. It is highly likely that if Lily is a lion, and Sandra took the milk, then John got the apple. We believe that if either Sandra took the milk, or Greg is gray, then Brian is white. There is a very good chance that if Sandra took the milk, or Greg is gray, then Julius is a rhino.
hypothesis: Chances are slight that brian is white, and Lily is a lion.
valid_hypothesis: Chances are slight that brian is white, and Lily is a lion.
invalid_hypothesis: It is certain that brian is white, and Lily is a lion.
hypothesis_assertion: Brian is white, and Lily is a lion.