There is a better than even chance that Brian is green. We believe that Bernhard is a rhino. There is little chance that Fred dropped the milk. We doubt that if 'Brian is green' or 'Bernhard is a rhino' or both then Sandra left the apple. It is probably not the case that if 'Bernhard is a rhino' or 'Fred dropped the milk' or both then Julius is a swan. It is probable that if either 'Fred dropped the milk' or 'Brian is green' but not both then John went to the hallway.
There is little chance that 'Sandra left the apple and Brian is green'.
There is little chance that 'Sandra left the apple and Brian is green'.
It is likely that 'Sandra left the apple and Brian 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
  0.6::factA.
  0.75::factB.
  0.1::factC.
  %hop1
  0.2::factX:-or(factA,factB).
  0.25::factY:-or(factB,factC).
  0.7::factZ:-xor(factC,factA).

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

  query(conclusion).
  
'Sandra left the apple and Brian is green'.