We believe that John dropped the apple. There is almost no chance that Lily is a lion. It is highly likely that Julius is a swan. Chances are slight that if 'Julius is a swan' or 'John dropped the apple' or both then Mary went to the office. There is little chance that if 'Julius is a swan' or 'Lily is a lion' or both then Brian is a rhino. It is improbable that if either 'Lily is a lion' or 'John dropped the apple' but not both then Sumit is thirsty.
It is unlikely that 'Brian is a rhino' or 'Sumit is thirsty' or both.
It is unlikely that 'Brian is a rhino' or 'Sumit is thirsty' or both.
There is a very good chance that 'Brian is a rhino' or 'Sumit is thirsty' 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.
  0.02::factB.
  0.9::factC.
  %hop1
  0.1::factX:-or(factC,factA).
  0.1::factY:-or(factC,factB).
  0.1::factZ:-xor(factB,factA).

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

  query(conclusion).
  
'Brian is a rhino' or 'Sumit is thirsty' or both.