It is certain that Daniel left the milk. It is impossible that Mary moved to the office. It is likely that Greg is a swan. It is impossible that if 'Greg is a swan and Mary moved to the office' then Bernhard is a frog. There is little chance that if 'Mary moved to the office and Daniel left the milk' then Emily is a mouse. There is almost no chance that if 'Mary moved to the office' or 'Greg is a swan' or both then John went to the hallway.
It is impossible that either 'Bernhard is a frog' or 'Emily is a mouse' but not both.
It is impossible that either 'Bernhard is a frog' or 'Emily is a mouse' but not both.
It is highly likely that either 'Bernhard is a frog' or 'Emily is a mouse' 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.
  0.7::factC.
  %hop1
  0.0::factX:-and(factC,factB).
  0.1::factY:-and(factB,factA).
  0.02::factZ:-or(factB,factC).

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

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