There is a better than even chance that Mary got the apple. It is certain that Jessica is a sheep. It is likely that Julius is a frog. There is almost no chance that if 'Jessica is a sheep' or 'Mary got the apple' or both then Fred left the football. There is a better than even chance that if 'Mary got the apple' or 'Julius is a frog' or both then Lily is green. We believe that if 'Mary got the apple and Jessica is a sheep' then Greg is yellow.
It is likely that either 'Fred left the football' or 'Julius is a frog' but not both.
It is likely that either 'Fred left the football' or 'Julius is a frog' but not both.
It is impossible that either 'Fred left the football' or 'Julius is a frog' 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
  0.6::factA.
  1.0::factB.
  0.7::factC.
  %hop1
  0.02::factX:-or(factB,factA).
  0.6::factY:-or(factA,factC).
  0.75::factZ:-and(factA,factB).

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

  query(conclusion).
  
Either 'Fred left the football' or 'Julius is a frog' but not both.