It is highly unlikely that John went to the bedroom. Chances are about even that Julius is yellow. Chances are slight that Lily is green. There is almost no chance that if 'John went to the bedroom and Julius is yellow' then Yann is hungry. It is unlikely that if either 'Julius is yellow' or 'Lily is green' but not both then Mary left the football. It is probably not the case that if 'Lily is green and John went to the bedroom' then Emily is a mouse.
It is impossible that 'Julius is yellow' or 'Yann is hungry' or both.
Chances are about even that 'Julius is yellow' or 'Yann is hungry' or both.
It is impossible that 'Julius is yellow' or 'Yann is hungry' 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
  0.05::factA.
  0.5::factB.
  0.1::factC.
  %hop1
  0.02::factX:-and(factA,factB).
  0.2::factY:-xor(factB,factC).
  0.25::factZ:-and(factC,factA).

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

  query(conclusion).
  
'Julius is yellow' or 'Yann is hungry' or both.