It is certain that Jessica is a cat. There is almost no chance that Greg is a swan. It is impossible that Sandra left the milk. There is a better than even chance that if either 'Sandra left the milk' or 'Greg is a swan' but not both then Brian is white. There is a better than even chance that if either 'Jessica is a cat' or 'Greg is a swan' but not both then Julius is a rhino. We believe that if 'Jessica is a cat' or 'Greg is a swan' or both then John took the apple.
It is certain that 'John took the apple' or 'Jessica is a cat' or both.
It is certain that 'John took the apple' or 'Jessica is a cat' or both.
There is almost no chance that 'John took the apple' or 'Jessica is a cat' 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
  1.0::factA.
  0.02::factB.
  0.0::factC.
  %hop1
  0.6::factX:-xor(factC,factB).
  0.6::factY:-xor(factA,factB).
  0.75::factZ:-or(factA,factB).

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

  query(conclusion).
  
'John took the apple' or 'Jessica is a cat' or both.