There is little chance that Bernhard is green. It is certain that Gertrude is a cat. We believe that Sandra got the football. It is unlikely that if 'Sandra got the football and Gertrude is a cat' then John went to the hallway. Chances are about even that if 'Gertrude is a cat and Sandra got the football' then Brian is white. It is likely that if 'Bernhard is green' or 'Sandra got the football' or both then Lily is a lion.
It is highly likely that 'Brian is white and Lily is a lion'.
It is probably not the case that 'Brian is white and Lily is a lion'.
It is highly likely that 'Brian is white and Lily is a lion'.

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

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

  query(conclusion).
  
'Brian is white and Lily is a lion'.