Chances are slight that John went to the bedroom. It is probably not the case that Brian is green. It is impossible that Bernhard is a frog. It is probably not the case that if 'John went to the bedroom and Brian is green' then Sandra got the milk. There is a better than even chance that if either 'Bernhard is a frog' or 'John went to the bedroom' but not both then Lily is a rhino. It is almost certain that if 'Brian is green and John went to the bedroom' then Mary dropped the milk.
It is highly likely that either 'Bernhard is a frog' or 'Mary dropped the milk' but not both.
There is almost no chance that either 'Bernhard is a frog' or 'Mary dropped the milk' but not both.
It is highly likely that either 'Bernhard is a frog' or 'Mary dropped 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
  0.1::factA.
  0.25::factB.
  0.0::factC.
  %hop1
  0.25::factX:-and(factA,factB).
  0.6::factY:-xor(factC,factA).
  0.95::factZ:-and(factB,factA).

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

  query(conclusion).
  
Either 'Bernhard is a frog' or 'Mary dropped the milk' but not both.