context: It is highly unlikely that Sandra took the football. There is almost no chance that Bernhard is a lion. It is unlikely that Bill went to the office. It is highly unlikely that if either Bill went to the office, or Sandra took the football, then Lily is yellow. It is highly unlikely that if either Bill went to the office, or Bernhard is a lion, then Mary put down the milk. There is a better than even chance that if Bill went to the office, or Bernhard is a lion, then Emily is a sheep.
hypothesis: It is impossible that bill went to the office, and Mary put down the milk.
valid_hypothesis: It is impossible that bill went to the office, and Mary put down the milk.
invalid_hypothesis: Chances are about even that bill went to the office, and Mary put down the milk.
hypothesis_assertion: Bill went to the office, and Mary put down the milk.