It is probable that Julius is a frog. It is almost certain that Brian is a rhino. There is almost no chance that Jessica is a cat. We doubt that if 'Julius is a frog' or 'Jessica is a cat' or both then Greg is white. We believe that if either 'Julius is a frog' or 'Jessica is a cat' but not both then Mary left the football. We believe that if 'Jessica is a cat and Brian is a rhino' then John took the apple.
Chances are about even that either 'Brian is a rhino' or 'Mary left the football' but not both.
Chances are about even that either 'Brian is a rhino' or 'Mary left the football' but not both.
It is highly unlikely that either 'Brian is a rhino' or 'Mary left the football' 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
  0.7::factA.
  0.95::factB.
  0.02::factC.
  %hop1
  0.2::factX:-or(factA,factC).
  0.75::factY:-xor(factA,factC).
  0.75::factZ:-and(factC,factB).

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

  query(conclusion).
  
Either 'Brian is a rhino' or 'Mary left the football' but not both.