There is a better than even chance that Gertrude is a wolf. It is highly unlikely that Bernhard is a lion. There is little chance that Mary moved to the garden. It is improbable that if either 'Bernhard is a lion' or 'Mary moved to the garden' but not both then Brian is green. It is probably the case that if either 'Gertrude is a wolf' or 'Bernhard is a lion' but not both then Greg is a frog. We believe that if either 'Gertrude is a wolf' or 'Bernhard is a lion' but not both then John discarded the apple.
There is a better than even chance that 'Bernhard is a lion' or 'Gertrude is a wolf' or both.
There is a better than even chance that 'Bernhard is a lion' or 'Gertrude is a wolf' or both.
It is highly unlikely that 'Bernhard is a lion' or 'Gertrude is a wolf' 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
  0.6::factA.
  0.05::factB.
  0.1::factC.
  %hop1
  0.1::factX:-xor(factB,factC).
  0.7::factY:-xor(factA,factB).
  0.75::factZ:-xor(factA,factB).

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

  query(conclusion).
  
'Bernhard is a lion' or 'Gertrude is a wolf' or both.