There is almost no chance that Brian is white. There is a better than even chance that Greg is a swan. It is improbable that Julius is a frog. We doubt that if 'Brian is white and Julius is a frog' then Mary went to the hallway. It is impossible that if 'Julius is a frog' or 'Greg is a swan' or both then Bernhard is yellow. We doubt that if 'Julius is a frog and Brian is white' then John put down the milk.
Chances are slight that 'Julius is a frog' or 'Bernhard is yellow' or both.
Chances are slight that 'Julius is a frog' or 'Bernhard is yellow' or both.
It is probable that 'Julius is a frog' or 'Bernhard 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
  0.02::factA.
  0.6::factB.
  0.1::factC.
  %hop1
  0.2::factX:-and(factA,factC).
  0.0::factY:-or(factC,factB).
  0.2::factZ:-and(factC,factA).

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

  query(conclusion).
  
'Julius is a frog' or 'Bernhard is yellow' or both.