It is likely that John went to the garden. There is a very good chance that Mary put down the apple. It is almost certain that Sandra left the football. Chances are slight that if 'John went to the garden' or 'Sandra left the football' or both then Brian is a swan. There is almost no chance that if either 'Mary put down the apple' or 'Sandra left the football' but not both then Lily is a lion. We believe that if either 'John went to the garden' or 'Sandra left the football' but not both then Bernhard is a frog.
It is almost certain that 'Mary put down the apple' or 'John went to the garden' or both.
It is almost certain that 'Mary put down the apple' or 'John went to the garden' or both.
There is little chance that 'Mary put down the apple' or 'John went to the garden' 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
  0.7::factA.
  0.8::factB.
  0.95::factC.
  %hop1
  0.1::factX:-or(factA,factC).
  0.02::factY:-xor(factB,factC).
  0.75::factZ:-xor(factA,factC).

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

  query(conclusion).
  
'Mary put down the apple' or 'John went to the garden' or both.