There is a better than even chance that Yann is tired. It is likely that John left the milk. There is little chance that Julius is white. It is probably not the case that if 'Julius is white' or 'Yann is tired' or both then Brian is a rhino. We believe that if 'Yann is tired and Julius is white' then Lily is gray. It is almost certain that if 'John left the milk' or 'Julius is white' or both then Fred went to the office.
It is highly unlikely that 'Lily is gray and Julius is white'.
It is highly unlikely that 'Lily is gray and Julius is white'.
There is a very good chance that 'Lily is gray and Julius 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
  0.6::factA.
  0.7::factB.
  0.1::factC.
  %hop1
  0.25::factX:-or(factC,factA).
  0.75::factY:-and(factA,factC).
  0.95::factZ:-or(factB,factC).

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

  query(conclusion).
  
'Lily is gray and Julius is white'.