It is probably the case that John left the milk. We believe that Greg is a rhino. It is probable that Lily is a swan. It is likely that if either 'Greg is a rhino' or 'Lily is a swan' but not both then Brian is white. It is highly unlikely that if either 'Lily is a swan' or 'Greg is a rhino' but not both then Julius is yellow. It is probably not the case that if either 'Greg is a rhino' or 'Lily is a swan' but not both then Bernhard is a lion.
Chances are about even that 'John left the milk and Lily is a swan'.
Chances are about even that 'John left the milk and Lily is a swan'.
It is certain that 'John left the milk and Lily is a swan'.

  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
  0.7::factA.
  0.75::factB.
  0.7::factC.
  %hop1
  0.7::factX:-xor(factB,factC).
  0.05::factY:-xor(factC,factB).
  0.25::factZ:-xor(factB,factC).

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

  query(conclusion).
  
'John left the milk and Lily is a swan'.