It is probably the case that John put down the milk. There is a better than even chance that Jeff dropped the apple. We believe that Jason is thirsty. There is a better than even chance that if 'John put down the milk' or 'Jason is thirsty' or both then Lily is gray. It is probable that if 'Jeff dropped the apple' or 'Jason is thirsty' or both then Daniel got the football. It is highly unlikely that if either 'Jason is thirsty' or 'John put down the milk' but not both then Julius is a swan.
Chances are slight that either 'Julius is a swan' or 'John put down the milk' but not both.
It is likely that either 'Julius is a swan' or 'John put down the milk' but not both.
Chances are slight that either 'Julius is a swan' or 'John put down the milk' 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.
  0.6::factB.
  0.75::factC.
  %hop1
  0.6::factX:-or(factA,factC).
  0.7::factY:-or(factB,factC).
  0.05::factZ:-xor(factC,factA).

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

  query(conclusion).
  
Either 'Julius is a swan' or 'John put down the milk' but not both.