context: Chances are slight that John went to the bedroom. Chances are about even that Sandra got the football. It is likely that Yann is tired. We believe that if John went to the bedroom, or Sandra got the football, then Emily is a sheep. Chances are slight that if either John went to the bedroom, or Yann is tired, then Brian is a lion. It is highly unlikely that if either Sandra got the football, or Yann is tired, then Greg is white.
hypothesis: It is impossible that greg is white, and John went to the bedroom.
valid_hypothesis: It is impossible that greg is white, and John went to the bedroom.
invalid_hypothesis: Chances are about even that greg is white, and John went to the bedroom.
hypothesis_assertion: Greg is white, and John went to the bedroom.