It is probably not the case that Lily is a swan. It is unlikely that Mary moved to the garden. Chances are slight that Brian is white. It is probable that if 'Lily is a swan and Mary moved to the garden' then Gertrude is a sheep. Chances are slight that if either 'Lily is a swan' or 'Mary moved to the garden' but not both then John put down the apple. There is almost no chance that if 'Mary moved to the garden and Lily is a swan' then Bernhard is a rhino.
It is probably not the case that 'Lily is a swan' or 'Bernhard is a rhino' or both.
It is probably not the case that 'Lily is a swan' or 'Bernhard is a rhino' or both.
We believe that 'Lily is a swan' or 'Bernhard is a rhino' 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
  0.25::factA.
  0.2::factB.
  0.1::factC.
  %hop1
  0.7::factX:-and(factA,factB).
  0.1::factY:-xor(factA,factB).
  0.02::factZ:-and(factB,factA).

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

  query(conclusion).
  
'Lily is a swan' or 'Bernhard is a rhino' or both.