It is likely that John took the apple. It is probably the case that Winona is a mouse. There is almost no chance that Lily is green. There is little chance that if 'Lily is green' or 'John took the apple' or both then Bernhard is white. It is probable that if 'Winona is a mouse' or 'Lily is green' or both then Emily is a sheep. It is highly likely that if 'Winona is a mouse and John took the apple' then Sandra left the milk.
Chances are about even that either 'Sandra left the milk' or 'Bernhard is white' but not both.
Chances are about even that either 'Sandra left the milk' or 'Bernhard is white' but not both.
It is impossible that either 'Sandra left the milk' or 'Bernhard is white' 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
  0.7::factA.
  0.7::factB.
  0.02::factC.
  %hop1
  0.1::factX:-or(factC,factA).
  0.7::factY:-or(factB,factC).
  0.9::factZ:-and(factB,factA).

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

  query(conclusion).
  
Either 'Sandra left the milk' or 'Bernhard is white' but not both.