It is impossible that Mary dropped the milk. It is improbable that Julius is a rhino. There is little chance that Lily is a swan. It is improbable that if 'Lily is a swan' or 'Julius is a rhino' or both then Jessica is a mouse. There is little chance that if either 'Julius is a rhino' or 'Lily is a swan' but not both then Brian is white. It is impossible that if either 'Lily is a swan' or 'Julius is a rhino' but not both then John grabbed the apple.
There is almost no chance that 'Jessica is a mouse' or 'John grabbed the apple' or both.
There is almost no chance that 'Jessica is a mouse' or 'John grabbed the apple' or both.
There is a better than even chance that 'Jessica is a mouse' or 'John grabbed the apple' 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
  0.0::factA.
  0.1::factB.
  0.1::factC.
  %hop1
  0.1::factX:-or(factC,factB).
  0.1::factY:-xor(factB,factC).
  0.0::factZ:-xor(factC,factB).

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

  query(conclusion).
  
'Jessica is a mouse' or 'John grabbed the apple' or both.