It is highly unlikely that Greg is white. Chances are about even that Gertrude is a sheep. Chances are about even that Julius is a rhino.
Chances are about even that julius is a rhino, or Greg is white.
Chances are about even that julius is a rhino, or Greg is white.
It is certain that julius is a rhino, or Greg is white.
Julius is a rhino, or Greg is white.