context: It is probably not the case that Fred went to the hallway. We doubt that Julius is white. It is probably not the case that Sandra left the milk. There is almost no chance that if Fred went to the hallway, and Julius is white, then John took the apple. Chances are about even that if Fred went to the hallway, and Sandra left the milk, then Bernhard is gray. It is unlikely that if either Fred went to the hallway, or Julius is white, then Greg is a frog.
hypothesis: It is impossible that greg is a frog, and Bernhard is gray.
valid_hypothesis: It is impossible that greg is a frog, and Bernhard is gray.
invalid_hypothesis: Chances are about even that greg is a frog, and Bernhard is gray.
hypothesis_assertion: Greg is a frog, and Bernhard is gray.