There is little chance that Bernhard is green. It is improbable that Jessica is a sheep. There is a better than even chance that Mary went to the office. It is likely that if either Jessica is a sheep, or Mary went to the office, then Julius is gray. There is a very good chance that if Jessica is a sheep, or Bernhard is green, then Greg is white. Chances are about even that if Mary went to the office, or Bernhard is green, then John discarded the milk.
It is unlikely that jessica is a sheep, or Greg is white.
This example is valid.