It is impossible that John is in the garden. Chances are slight that Bernhard is a frog. There is almost no chance that Julius is white. Chances are about even that if either 'Bernhard is a frog' or 'Julius is white' but not both then Jessica is a mouse. It is almost certain that if either 'Bernhard is a frog' or 'John is in the garden' but not both then Gertrude is a cat. It is probably the case that if either 'Bernhard is a frog' or 'Julius is white' but not both then Sandra left the milk.
Chances are slight that 'Bernhard is a frog' or 'Gertrude is a cat' or both.
Chances are slight that 'Bernhard is a frog' or 'Gertrude is a cat' or both.
There is a better than even chance that 'Bernhard is a frog' or 'Gertrude is a cat' 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
  0.0::factA.
  0.1::factB.
  0.02::factC.
  %hop1
  0.5::factX:-xor(factB,factC).
  0.95::factY:-xor(factB,factA).
  0.7::factZ:-xor(factB,factC).

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

  query(conclusion).
  
'Bernhard is a frog' or 'Gertrude is a cat' or both.