We believe that Bernhard is yellow. Chances are slight that Lily is a swan. It is impossible that Sandra got the football. There is a better than even chance that if 'Bernhard is yellow and Lily is a swan' then Gertrude is a mouse. It is almost certain that if either 'Bernhard is yellow' or 'Lily is a swan' but not both then Julius is a lion. It is likely that if either 'Lily is a swan' or 'Sandra got the football' but not both then Mary put down the milk.
We believe that 'Julius is a lion' or 'Lily is a swan' or both.
We believe that 'Julius is a lion' or 'Lily is a swan' or both.
There is almost no chance that 'Julius is a lion' or 'Lily is a swan' or both.

  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
  0.75::factA.
  0.1::factB.
  0.0::factC.
  %hop1
  0.6::factX:-and(factA,factB).
  0.95::factY:-xor(factA,factB).
  0.7::factZ:-xor(factB,factC).

  %hop2
  conclusion:-or(factY,factB).

  query(conclusion).
  
'Julius is a lion' or 'Lily is a swan' or both.