It is certain that Emily is a sheep. It is impossible that Greg is white. It is almost certain that Brian is a lion. Chances are slight that if either 'Greg is white' or 'Brian is a lion' but not both then Bernhard is a frog. It is unlikely that if 'Greg is white' or 'Brian is a lion' or both then John got the milk. It is highly likely that if 'Greg is white and Emily is a sheep' then Sandra is in the kitchen.
It is highly likely that either 'Bernhard is a frog' or 'Emily is a sheep' but not both.
It is highly likely that either 'Bernhard is a frog' or 'Emily is a sheep' but not both.
There is almost no chance that either 'Bernhard is a frog' or 'Emily is a sheep' 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
  1.0::factA.
  0.0::factB.
  0.95::factC.
  %hop1
  0.1::factX:-xor(factB,factC).
  0.2::factY:-or(factB,factC).
  0.9::factZ:-and(factB,factA).

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

  query(conclusion).
  
Either 'Bernhard is a frog' or 'Emily is a sheep' but not both.