We believe that Yann is tired. It is impossible that Brian is a frog. We believe that John went to the garden. It is likely that if 'Brian is a frog' or 'Yann is tired' or both then Julius is a rhino. It is certain that if either 'Brian is a frog' or 'Yann is tired' but not both then Sandra left the milk. It is improbable that if 'John went to the garden' or 'Brian is a frog' or both then Bernhard is yellow.
We believe that 'Julius is a rhino' or 'Yann is tired' or both.
We believe that 'Julius is a rhino' or 'Yann is tired' or both.
There is almost no chance that 'Julius is a rhino' or 'Yann is tired' 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
  0.75::factA.
  0.0::factB.
  0.75::factC.
  %hop1
  0.7::factX:-or(factB,factA).
  1.0::factY:-xor(factB,factA).
  0.1::factZ:-or(factC,factB).

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

  query(conclusion).
  
'Julius is a rhino' or 'Yann is tired' or both.