There is a very good chance that Daniel took the milk. It is likely that Greg is yellow. Chances are about even that John dropped the apple. We believe that if 'Daniel took the milk' or 'John dropped the apple' or both then Brian is white. It is unlikely that if 'Daniel took the milk and John dropped the apple' then Julius is green. There is almost no chance that if either 'Daniel took the milk' or 'Greg is yellow' but not both then Gertrude is a cat.
Chances are about even that 'John dropped the apple' or 'Gertrude is a cat' or both.
Chances are about even that 'John dropped the apple' or 'Gertrude is a cat' or both.
There is almost no chance that 'John dropped the apple' or 'Gertrude is a cat' 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
  0.8::factA.
  0.7::factB.
  0.5::factC.
  %hop1
  0.75::factX:-or(factA,factC).
  0.2::factY:-and(factA,factC).
  0.02::factZ:-xor(factA,factB).

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

  query(conclusion).
  
'John dropped the apple' or 'Gertrude is a cat' or both.