There is a better than even chance that Greg is a rhino. It is likely that Mary moved to the garden. It is almost certain that Bernhard is a swan. It is certain that if 'Bernhard is a swan and Mary moved to the garden' then Sandra grabbed the apple. It is probably not the case that if either 'Greg is a rhino' or 'Mary moved to the garden' but not both then Gertrude is a mouse. There is little chance that if 'Greg is a rhino' or 'Mary moved to the garden' or both then Lily is a frog.
It is improbable that either 'Gertrude is a mouse' or 'Sandra grabbed the apple' but not both.
There is a better than even chance that either 'Gertrude is a mouse' or 'Sandra grabbed the apple' but not both.
It is improbable that either 'Gertrude is a mouse' or 'Sandra grabbed the apple' but not 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
  0.6::factA.
  0.7::factB.
  0.95::factC.
  %hop1
  1.0::factX:-and(factC,factB).
  0.25::factY:-xor(factA,factB).
  0.1::factZ:-or(factA,factB).

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

  query(conclusion).
  
Either 'Gertrude is a mouse' or 'Sandra grabbed the apple' but not both.