It is probably not the case that Brian is yellow. Chances are slight that Julius is a swan. Chances are slight that Winona is a sheep. It is probably not the case that if either 'Winona is a sheep' or 'Julius is a swan' but not both then Lily is a rhino. It is almost certain that if either 'Julius is a swan' or 'Brian is yellow' but not both then Sandra dropped the milk. We believe that if either 'Julius is a swan' or 'Winona is a sheep' but not both then Mary went to the kitchen.
We believe that 'Lily is a rhino' or 'Brian is yellow' or both.
It is probably not the case that 'Lily is a rhino' or 'Brian is yellow' or both.
We believe that 'Lily is a rhino' or 'Brian is yellow' or both.

  and(A,B) :- A,B.
  or(A,B) :- A;B.
  nand(A,B) :- not(and(A,B)).
  nor(A,B) :- not(or(A,B)).
  xor(A,B) :- or(A,B), nand(A,B).

  %hop0
  0.25::factA.
  0.1::factB.
  0.1::factC.
  %hop1
  0.25::factX:-xor(factC,factB).
  0.95::factY:-xor(factB,factA).
  0.75::factZ:-xor(factB,factC).

  %hop2
  conclusion:-or(factX,factA).

  query(conclusion).
  
'Lily is a rhino' or 'Brian is yellow' or both.