There is almost no chance that Mary dropped the milk. It is highly likely that John went to the garden. It is improbable that Bernhard is a rhino. It is highly unlikely that if 'John went to the garden' or 'Mary dropped the milk' or both then Sandra grabbed the apple. It is unlikely that if either 'Bernhard is a rhino' or 'Mary dropped the milk' but not both then Lily is a swan. It is unlikely that if 'Mary dropped the milk and Bernhard is a rhino' then Brian is a lion.
We believe that 'Sandra grabbed the apple and Lily is a swan'.
It is impossible that 'Sandra grabbed the apple and Lily is a swan'.
We believe that 'Sandra grabbed the apple and Lily is a swan'.

  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
  0.02::factA.
  0.9::factB.
  0.1::factC.
  %hop1
  0.05::factX:-or(factB,factA).
  0.2::factY:-xor(factC,factA).
  0.2::factZ:-and(factA,factC).

  %hop2
  conclusion:-and(factX,factY).

  query(conclusion).
  
'Sandra grabbed the apple and Lily is a swan'.