Chances are about even that Gertrude is a cat. It is almost certain that Bernhard is white. It is probably the case that Julius is a lion. There is a better than even chance that if 'Bernhard is white and Gertrude is a cat' then Lily is a rhino. It is probably the case that if 'Gertrude is a cat and Bernhard is white' then Mary went to the office. It is likely that if 'Julius is a lion' or 'Bernhard is white' or both then Brian is white.
Chances are about even that either 'Julius is a lion' or 'Brian is white' but not both.
Chances are about even that either 'Julius is a lion' or 'Brian is white' but not both.
There is almost no chance that either 'Julius is a lion' or 'Brian is white' 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
  0.5::factA.
  0.95::factB.
  0.7::factC.
  %hop1
  0.6::factX:-and(factB,factA).
  0.7::factY:-and(factA,factB).
  0.7::factZ:-or(factC,factB).

  %hop2
  conclusion:-xor(factC,factZ).

  query(conclusion).
  
Either 'Julius is a lion' or 'Brian is white' but not both.