It is likely that Mary went to the garden. It is highly unlikely that Winona is a mouse. Chances are about even that Jeff dropped the apple. It is likely that if either 'Jeff dropped the apple' or 'Winona is a mouse' but not both then Bernhard is green. There is almost no chance that if either 'Mary went to the garden' or 'Winona is a mouse' but not both then Gertrude is a cat. It is unlikely that if 'Mary went to the garden' or 'Jeff dropped the apple' or both then Brian is a frog.
There is almost no chance that 'Jeff dropped the apple and Winona is a mouse'.
There is almost no chance that 'Jeff dropped the apple and Winona is a mouse'.
It is likely that 'Jeff dropped the apple and Winona is a mouse'.

  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.
  0.05::factB.
  0.5::factC.
  %hop1
  0.7::factX:-xor(factC,factB).
  0.02::factY:-xor(factA,factB).
  0.2::factZ:-or(factA,factC).

  %hop2
  conclusion:-and(factC,factB).

  query(conclusion).
  
'Jeff dropped the apple and Winona is a mouse'.