It is almost certain that Julius is a swan. Chances are about even that Greg is a lion. There is almost no chance that Mary took the football. It is almost certain that if either 'Greg is a lion' or 'Julius is a swan' but not both then Brian is a rhino. It is unlikely that if 'Mary took the football' or 'Greg is a lion' or both then Sandra left the milk. There is little chance that if either 'Mary took the football' or 'Greg is a lion' but not both then John went to the garden.
There is almost no chance that 'Brian is a rhino' or 'Sandra left the milk' or both.
There is a better than even chance that 'Brian is a rhino' or 'Sandra left the milk' or both.
There is almost no chance that 'Brian is a rhino' or 'Sandra left the milk' 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
  0.95::factA.
  0.5::factB.
  0.02::factC.
  %hop1
  0.95::factX:-xor(factB,factA).
  0.2::factY:-or(factC,factB).
  0.1::factZ:-xor(factC,factB).

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

  query(conclusion).
  
'Brian is a rhino' or 'Sandra left the milk' or both.