It is improbable that Brian is green. It is likely that Bernhard is a rhino. We believe that Greg is yellow. It is impossible that if either 'Bernhard is a rhino' or 'Greg is yellow' but not both then Mary went to the garden. It is highly unlikely that if 'Bernhard is a rhino' or 'Greg is yellow' or both then Lily is a frog. It is likely that if 'Brian is green and Greg is yellow' then John got the apple.
It is likely that either 'Bernhard is a rhino' or 'Brian is green' but not both.
It is likely that either 'Bernhard is a rhino' or 'Brian is green' but not both.
It is improbable that either 'Bernhard is a rhino' or 'Brian is green' 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
  0.1::factA.
  0.7::factB.
  0.75::factC.
  %hop1
  0.0::factX:-xor(factB,factC).
  0.05::factY:-or(factB,factC).
  0.7::factZ:-and(factA,factC).

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

  query(conclusion).
  
Either 'Bernhard is a rhino' or 'Brian is green' but not both.