We believe that Julius is white. There is little chance that Brian is a swan. It is unlikely that Sandra got the milk. It is probably the case that if 'Brian is a swan and Julius is white' then Lily is a frog. There is a very good chance that if 'Julius is white and Sandra got the milk' then John moved to the garden. There is little chance that if 'Julius is white and Sandra got the milk' then Mary dropped the milk.
There is a very good chance that 'Brian is a swan' or 'Julius is white' or both.
There is a very good chance that 'Brian is a swan' or 'Julius is white' or both.
It is probably not the case that 'Brian is a swan' or 'Julius is white' 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.
  0.2::factC.
  %hop1
  0.7::factX:-and(factB,factA).
  0.8::factY:-and(factA,factC).
  0.1::factZ:-and(factA,factC).

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

  query(conclusion).
  
'Brian is a swan' or 'Julius is white' or both.