It is probably not the case that Greg is yellow. Chances are slight that Sandra got the football. It is improbable that Bernhard is a frog. There is a very good chance that if 'Sandra got the football and Bernhard is a frog' then Brian is a lion. It is probable that if 'Greg is yellow' or 'Bernhard is a frog' or both then Julius is yellow. It is highly likely that if either 'Bernhard is a frog' or 'Greg is yellow' but not both then Jeff went to the garden.
It is almost certain that either 'Bernhard is a frog' or 'Brian is a lion' but not both.
Chances are slight that either 'Bernhard is a frog' or 'Brian is a lion' but not both.
It is almost certain that either 'Bernhard is a frog' or 'Brian 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
  0.25::factA.
  0.1::factB.
  0.1::factC.
  %hop1
  0.8::factX:-and(factB,factC).
  0.7::factY:-or(factA,factC).
  0.9::factZ:-xor(factC,factA).

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

  query(conclusion).
  
Either 'Bernhard is a frog' or 'Brian is a lion' but not both.