There is little chance that Julius is a swan. It is impossible that Antoine is thirsty. It is probable that Lily is a swan. There is a very good chance that if 'Antoine is thirsty' or 'Lily is a swan' or both then Brian is a rhino. There is little chance that if either 'Lily is a swan' or 'Julius is a swan' but not both then Bernhard is a frog. It is probable that if 'Lily is a swan' or 'Julius is a swan' or both then Mary got the football.
Chances are about even that either 'Mary got the football' or 'Bernhard is a frog' but not both.
Chances are about even that either 'Mary got the football' or 'Bernhard is a frog' but not both.
It is impossible that either 'Mary got the football' or 'Bernhard 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
  0.1::factA.
  0.0::factB.
  0.7::factC.
  %hop1
  0.8::factX:-or(factB,factC).
  0.1::factY:-xor(factC,factA).
  0.7::factZ:-or(factC,factA).

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

  query(conclusion).
  
Either 'Mary got the football' or 'Bernhard is a frog' but not both.