It is almost certain that Bill went to the bedroom. It is likely that Jessica is a mouse. It is highly unlikely that Greg is a swan. There is a very good chance that if either 'Bill went to the bedroom' or 'Greg is a swan' but not both then Sumit is thirsty. It is probable that if 'Bill went to the bedroom and Jessica is a mouse' then Sandra put down the milk. It is improbable that if 'Jessica is a mouse and Greg is a swan' then Julius is yellow.
Chances are about even that either 'Greg is a swan' or 'Sandra put down the milk' but not both.
Chances are about even that either 'Greg is a swan' or 'Sandra put down the milk' but not both.
It is highly unlikely that either 'Greg is a swan' or 'Sandra 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
  0.95::factA.
  0.7::factB.
  0.05::factC.
  %hop1
  0.8::factX:-xor(factA,factC).
  0.7::factY:-and(factA,factB).
  0.1::factZ:-and(factB,factC).

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

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