It is probably not the case that Winona is a wolf. It is improbable that Gertrude is a mouse. Chances are slight that Lily is a rhino. There is almost no chance that if either 'Winona is a wolf' or 'Gertrude is a mouse' but not both then John discarded the milk. It is likely that if 'Winona is a wolf' or 'Lily is a rhino' or both then Julius is white. It is almost certain that if 'Gertrude is a mouse and Lily is a rhino' then Mary went to the garden.
There is a very good chance that 'John discarded the milk' or 'Gertrude is a mouse' or both.
There is little chance that 'John discarded the milk' or 'Gertrude is a mouse' or both.
There is a very good chance that 'John discarded the milk' or 'Gertrude is a mouse' 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
  0.02::factX:-xor(factA,factB).
  0.7::factY:-or(factA,factC).
  0.95::factZ:-and(factB,factC).

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

  query(conclusion).
  
'John discarded the milk' or 'Gertrude is a mouse' or both.