There is a very good chance that Brian is a swan. It is certain that Yann is thirsty. It is likely that Bernhard is a frog. We doubt that if 'Brian is a swan and Yann is thirsty' then Emily is a wolf. There is almost no chance that if 'Bernhard is a frog' or 'Yann is thirsty' or both then Mary took the football. There is little chance that if 'Bernhard is a frog and Yann is thirsty' then Lily is gray.
We doubt that 'Emily is a wolf' or 'Yann is thirsty' or both.
It is certain that 'Emily is a wolf' or 'Yann is thirsty' or both.
We doubt that 'Emily is a wolf' or 'Yann is thirsty' or 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
  0.8::factA.
  1.0::factB.
  0.7::factC.
  %hop1
  0.2::factX:-and(factA,factB).
  0.02::factY:-or(factC,factB).
  0.1::factZ:-and(factC,factB).

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

  query(conclusion).
  
'Emily is a wolf' or 'Yann is thirsty' or both.