It is highly unlikely that Julius is a frog. Chances are about even that Lily is yellow. It is improbable that Fred left the football. Chances are slight that if 'Lily is yellow' or 'Fred left the football' or both then Bernhard is green. It is probably the case that if either 'Fred left the football' or 'Lily is yellow' but not both then Bill went to the bedroom. It is unlikely that if either 'Lily is yellow' or 'Fred left the football' but not both then Brian is white.
There is a better than even chance that 'Fred left the football' or 'Lily is yellow' or both.
There is a better than even chance that 'Fred left the football' or 'Lily is yellow' or both.
There is almost no chance that 'Fred left the football' or 'Lily is yellow' 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
  0.1::factX:-or(factB,factC).
  0.7::factY:-xor(factC,factB).
  0.2::factZ:-xor(factB,factC).

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

  query(conclusion).
  
'Fred left the football' or 'Lily is yellow' or both.