It is highly likely that Sandra got the milk. It is unlikely that Bernhard is a swan. There is little chance that Bill went to the office. Chances are about even that if either 'Sandra got the milk' or 'Bernhard is a swan' but not both then Emily is a sheep. It is highly likely that if 'Sandra got the milk and Bill went to the office' then Brian is a lion. It is highly likely that if 'Bernhard is a swan' or 'Sandra got the milk' or both then Julius is a frog.
It is almost certain that either 'Julius is a frog' or 'Emily is a sheep' but not both.
Chances are about even that either 'Julius is a frog' or 'Emily is a sheep' but not both.
It is almost certain that either 'Julius is a frog' or 'Emily is a sheep' 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
  0.9::factA.
  0.2::factB.
  0.1::factC.
  %hop1
  0.5::factX:-xor(factA,factB).
  0.9::factY:-and(factA,factC).
  0.9::factZ:-or(factB,factA).

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

  query(conclusion).
  
Either 'Julius is a frog' or 'Emily is a sheep' but not both.