It is highly likely that Bernhard is gray. There is a very good chance that Gertrude is a mouse. Chances are about even that Bill moved to the office. Chances are slight that if 'Bill moved to the office' or 'Bernhard is gray' or both then Winona is a cat. There is little chance that if 'Gertrude is a mouse' or 'Bill moved to the office' or both then Julius is yellow. We doubt that if either 'Gertrude is a mouse' or 'Bernhard is gray' but not both then Lily is a lion.
It is impossible that 'Lily is a lion and Julius is yellow'.
It is impossible that 'Lily is a lion and Julius is yellow'.
There is a very good chance that 'Lily is a lion and Julius is yellow'.

  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
  0.9::factA.
  0.8::factB.
  0.5::factC.
  %hop1
  0.1::factX:-or(factC,factA).
  0.1::factY:-or(factB,factC).
  0.2::factZ:-xor(factB,factA).

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

  query(conclusion).
  
'Lily is a lion and Julius is yellow'.