It is probably the case that John moved to the garden. It is improbable that Jessica is a sheep. It is certain that Brian is yellow. We doubt that if 'John moved to the garden and Brian is yellow' then Bernhard is green. Chances are slight that if either 'Jessica is a sheep' or 'Brian is yellow' but not both then Greg is a swan. There is a very good chance that if 'Jessica is a sheep' or 'John moved to the garden' or both then Mary left the milk.
It is highly likely that either 'Jessica is a sheep' or 'Bernhard is green' but not both.
It is unlikely that either 'Jessica is a sheep' or 'Bernhard is green' but not both.
It is highly likely that either 'Jessica is a sheep' or 'Bernhard 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
  0.7::factA.
  0.1::factB.
  1.0::factC.
  %hop1
  0.2::factX:-and(factA,factC).
  0.1::factY:-xor(factB,factC).
  0.8::factZ:-or(factB,factA).

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

  query(conclusion).
  
Either 'Jessica is a sheep' or 'Bernhard is green' but not both.