There is almost no chance that Bernhard is yellow. Chances are slight that Jessica is a mouse. It is probably the case that Lily is a lion. We doubt that if either 'Lily is a lion' or 'Bernhard is yellow' but not both then Jason is bored. It is highly unlikely that if 'Lily is a lion and Bernhard is yellow' then Greg is a swan. We doubt that if 'Bernhard is yellow' or 'Jessica is a mouse' or both then John went to the garden.
It is probably the case that either 'Greg is a swan' or 'Lily is a lion' but not both.
It is probably the case that either 'Greg is a swan' or 'Lily is a lion' but not both.
It is unlikely that either 'Greg is a swan' or 'Lily 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
  0.02::factA.
  0.1::factB.
  0.7::factC.
  %hop1
  0.2::factX:-xor(factC,factA).
  0.05::factY:-and(factC,factA).
  0.2::factZ:-or(factA,factB).

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

  query(conclusion).
  
Either 'Greg is a swan' or 'Lily is a lion' but not both.