We believe that Greg is a frog. We doubt that Jessica is a cat. It is likely that Bernhard is yellow. It is unlikely that if 'Bernhard is yellow' or 'Greg is a frog' or both then John picked up the apple. It is certain that if 'Bernhard is yellow' or 'Greg is a frog' or both then Lily is a rhino. It is highly unlikely that if either 'Greg is a frog' or 'Jessica is a cat' but not both then Mary went to the office.
It is highly likely that either 'Lily is a rhino' or 'Mary went to the office' but not both.
It is highly likely that either 'Lily is a rhino' or 'Mary went to the office' but not both.
It is impossible that either 'Lily is a rhino' or 'Mary went to the office' 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.
  0.2::factB.
  0.7::factC.
  %hop1
  0.2::factX:-or(factC,factA).
  1.0::factY:-or(factC,factA).
  0.05::factZ:-xor(factA,factB).

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

  query(conclusion).
  
Either 'Lily is a rhino' or 'Mary went to the office' but not both.