We doubt that Gertrude is a mouse. There is a better than even chance that Julius is green. Chances are about even that Sandra dropped the milk. It is impossible that if 'Gertrude is a mouse and Julius is green' then Brian is a swan. Chances are about even that if either 'Sandra dropped the milk' or 'Gertrude is a mouse' but not both then Lily is a rhino. There is a very good chance that if either 'Gertrude is a mouse' or 'Sandra dropped the milk' but not both then Fred put down the apple.
There is a better than even chance that either 'Gertrude is a mouse' or 'Julius is green' but not both.
There is a better than even chance that either 'Gertrude is a mouse' or 'Julius is green' but not both.
There is little chance that either 'Gertrude is a mouse' or 'Julius is green' 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
  0.2::factA.
  0.6::factB.
  0.5::factC.
  %hop1
  0.0::factX:-and(factA,factB).
  0.5::factY:-xor(factC,factA).
  0.8::factZ:-xor(factA,factC).

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

  query(conclusion).
  
Either 'Gertrude is a mouse' or 'Julius is green' but not both.