There is little chance that Mary grabbed the milk. We doubt that Brian is a frog. It is probably not the case that Lily is a swan. It is probably the case that if 'Brian is a frog' or 'Mary grabbed the milk' or both then Jason is tired. Chances are about even that if 'Brian is a frog and Mary grabbed the milk' then Julius is yellow. There is a very good chance that if 'Lily is a swan' or 'Mary grabbed the milk' or both then Bernhard is green.
It is probable that 'Julius is yellow and Bernhard is green'.
It is impossible that 'Julius is yellow and Bernhard is green'.
It is probable that 'Julius is yellow and Bernhard is green'.

  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.
  0.2::factB.
  0.25::factC.
  %hop1
  0.7::factX:-or(factB,factA).
  0.5::factY:-and(factB,factA).
  0.8::factZ:-or(factC,factA).

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

  query(conclusion).
  
'Julius is yellow and Bernhard is green'.