Chances are about even that Greg is a rhino. We believe that Bernhard is a frog. It is almost certain that Jessica is a mouse. It is highly likely that if 'Greg is a rhino and Jessica is a mouse' then Julius is white. It is likely that if 'Jessica is a mouse' or 'Greg is a rhino' or both then Brian is green. It is unlikely that if 'Jessica is a mouse and Greg is a rhino' then John moved to the garden.
Chances are about even that either 'Jessica is a mouse' or 'Greg is a rhino' but not both.
Chances are about even that either 'Jessica is a mouse' or 'Greg is a rhino' but not both.
It is almost certain that either 'Jessica is a mouse' or 'Greg 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
  0.5::factA.
  0.75::factB.
  0.95::factC.
  %hop1
  0.9::factX:-and(factA,factC).
  0.7::factY:-or(factC,factA).
  0.2::factZ:-and(factC,factA).

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

  query(conclusion).
  
Either 'Jessica is a mouse' or 'Greg is a rhino' but not both.