It is highly unlikely that Antoine is thirsty. It is probably the case that Bernhard is a swan. It is almost certain that Gertrude is a mouse. It is likely that if 'Bernhard is a swan and Gertrude is a mouse' then Mary moved to the garden. There is little chance that if either 'Gertrude is a mouse' or 'Antoine is thirsty' but not both then John dropped the apple. There is a very good chance that if 'Gertrude is a mouse and Bernhard is a swan' then Brian is a frog.
It is likely that either 'Bernhard is a swan' or 'Brian is a frog' but not both.
We doubt that either 'Bernhard is a swan' or 'Brian is a frog' but not both.
It is likely that either 'Bernhard is a swan' or 'Brian is a frog' 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
  0.05::factA.
  0.7::factB.
  0.95::factC.
  %hop1
  0.7::factX:-and(factB,factC).
  0.1::factY:-xor(factC,factA).
  0.8::factZ:-and(factC,factB).

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

  query(conclusion).
  
Either 'Bernhard is a swan' or 'Brian is a frog' but not both.