It is likely that Bernhard is a rhino. It is improbable that Mary grabbed the apple. There is a very good chance that Jeff went to the bedroom. Chances are slight that if 'Bernhard is a rhino' or 'Jeff went to the bedroom' or both then Yann is hungry. It is highly likely that if either 'Mary grabbed the apple' or 'Bernhard is a rhino' but not both then Lily is a lion. It is likely that if 'Jeff went to the bedroom' or 'Mary grabbed the apple' or both then Brian is white.
There is a better than even chance that 'Yann is hungry' or 'Lily is a lion' or both.
There is a better than even chance that 'Yann is hungry' or 'Lily is a lion' or both.
It is impossible that 'Yann is hungry' or 'Lily is a lion' 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
  0.7::factA.
  0.1::factB.
  0.8::factC.
  %hop1
  0.1::factX:-or(factA,factC).
  0.9::factY:-xor(factB,factA).
  0.7::factZ:-or(factC,factB).

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

  query(conclusion).
  
'Yann is hungry' or 'Lily is a lion' or both.