It is probably not the case that Emily is a wolf. It is unlikely that Brian is gray. Chances are about even that Greg is yellow. It is likely that if 'Brian is gray' or 'Emily is a wolf' or both then Julius is yellow. There is almost no chance that if either 'Emily is a wolf' or 'Greg is yellow' but not both then Bernhard is a swan. It is highly likely that if either 'Brian is gray' or 'Greg is yellow' but not both then Yann is tired.
It is unlikely that either 'Julius is yellow' or 'Emily is a wolf' but not both.
It is unlikely that either 'Julius is yellow' or 'Emily is a wolf' but not both.
It is probably the case that either 'Julius is yellow' or 'Emily is a wolf' 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
  0.25::factA.
  0.2::factB.
  0.5::factC.
  %hop1
  0.7::factX:-or(factB,factA).
  0.02::factY:-xor(factA,factC).
  0.9::factZ:-xor(factB,factC).

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

  query(conclusion).
  
Either 'Julius is yellow' or 'Emily is a wolf' but not both.