We believe that Daniel grabbed the milk. It is certain that John moved to the office. It is likely that Mary dropped the apple. It is highly unlikely that if 'Daniel grabbed the milk' or 'Mary dropped the apple' or both then Julius is a rhino. There is a better than even chance that if 'Daniel grabbed the milk and John moved to the office' then Brian is white. We doubt that if either 'John moved to the office' or 'Daniel grabbed the milk' but not both then Bernhard is a swan.
Chances are slight that 'Mary dropped the apple' or 'Bernhard is a swan' or both.
It is probable that 'Mary dropped the apple' or 'Bernhard is a swan' or both.
Chances are slight that 'Mary dropped the apple' or 'Bernhard 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.
  1.0::factB.
  0.7::factC.
  %hop1
  0.05::factX:-or(factA,factC).
  0.6::factY:-and(factA,factB).
  0.2::factZ:-xor(factB,factA).

  %hop2
  conclusion:-or(factC,factZ).

  query(conclusion).
  
'Mary dropped the apple' or 'Bernhard is a swan' or both.