It is highly unlikely that Mary got the football. It is probably not the case that Bernhard is yellow. Chances are slight that John grabbed the apple. It is certain that if 'Mary got the football' or 'Bernhard is yellow' or both then Brian is gray. It is highly likely that if either 'John grabbed the apple' or 'Bernhard is yellow' but not both then Julius is a lion. Chances are slight that if 'Bernhard is yellow and John grabbed the apple' then Greg is a frog.
It is almost certain that either 'Bernhard is yellow' or 'Julius is a lion' but not both.
There is little chance that either 'Bernhard is yellow' or 'Julius is a lion' but not both.
It is almost certain that either 'Bernhard is yellow' or 'Julius is a lion' 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
  0.05::factA.
  0.25::factB.
  0.1::factC.
  %hop1
  1.0::factX:-or(factA,factB).
  0.9::factY:-xor(factC,factB).
  0.1::factZ:-and(factB,factC).

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

  query(conclusion).
  
Either 'Bernhard is yellow' or 'Julius is a lion' but not both.