context: Chances are slight that Mary went to the hallway. It is probably the case that Greg is a swan. It is certain that John dropped the apple. Chances are about even that if either Greg is a swan, or John dropped the apple, then Bernhard is white. It is improbable that if either Greg is a swan, or John dropped the apple, then Brian is a lion. We believe that if either Mary went to the hallway, or Greg is a swan, then Emily is a wolf.
hypothesis: It is impossible that brian is a lion, and Greg is a swan.
valid_hypothesis: It is impossible that brian is a lion, and Greg is a swan.
invalid_hypothesis: It is likely that brian is a lion, and Greg is a swan.
hypothesis_assertion: Brian is a lion, and Greg is a swan.