It is improbable that Fred dropped the apple. It is improbable that Bernhard is white. There is little chance that Sandra put down the milk. There is a better than even chance that if 'Bernhard is white' or 'Fred dropped the apple' or both then Greg is a swan. It is probable that if 'Sandra put down the milk' or 'Fred dropped the apple' or both then Julius is a lion. It is probably not the case that if either 'Bernhard is white' or 'Sandra put down the milk' but not both then Brian is yellow.
It is almost certain that 'Sandra put down the milk' or 'Greg is a swan' or both.
It is unlikely that 'Sandra put down the milk' or 'Greg is a swan' or both.
It is almost certain that 'Sandra put down the milk' or 'Greg is a swan' 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
  0.1::factA.
  0.1::factB.
  0.1::factC.
  %hop1
  0.6::factX:-or(factB,factA).
  0.7::factY:-or(factC,factA).
  0.25::factZ:-xor(factB,factC).

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

  query(conclusion).
  
'Sandra put down the milk' or 'Greg is a swan' or both.