Chances are about even that Sandra dropped the milk. It is impossible that Julius is a swan. There is little chance that Mary put down the apple. Chances are slight that if either 'Mary put down the apple' or 'Julius is a swan' but not both then Bernhard is a frog. It is probably the case that if either 'Julius is a swan' or 'Sandra dropped the milk' but not both then John went to the kitchen. There is a better than even chance that if either 'Julius is a swan' or 'Sandra dropped the milk' but not both then Brian is white.
We believe that 'Sandra dropped the milk and Brian is white'.
It is probably not the case that 'Sandra dropped the milk and Brian is white'.
We believe that 'Sandra dropped the milk and Brian is white'.

  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
  0.5::factA.
  0.0::factB.
  0.1::factC.
  %hop1
  0.1::factX:-xor(factC,factB).
  0.7::factY:-xor(factB,factA).
  0.6::factZ:-xor(factB,factA).

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

  query(conclusion).
  
'Sandra dropped the milk and Brian is white'.