We believe that Lily is a rhino. It is highly likely that Emily is a mouse. We believe that Julius is a frog. We believe that if either 'Lily is a rhino' or 'Julius is a frog' but not both then Winona is a wolf. There is a better than even chance that if 'Emily is a mouse and Lily is a rhino' then Sandra dropped the milk. Chances are about even that if 'Emily is a mouse and Lily is a rhino' then John discarded the apple.
Chances are about even that either 'Julius is a frog' or 'Lily is a rhino' but not both.
Chances are about even that either 'Julius is a frog' or 'Lily is a rhino' but not both.
It is certain that either 'Julius is a frog' or 'Lily is a rhino' 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
  0.75::factA.
  0.9::factB.
  0.75::factC.
  %hop1
  0.75::factX:-xor(factA,factC).
  0.6::factY:-and(factB,factA).
  0.5::factZ:-and(factB,factA).

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

  query(conclusion).
  
Either 'Julius is a frog' or 'Lily is a rhino' but not both.