It is improbable that Julius is white. Chances are about even that Mary left the milk. There is a better than even chance that Brian is a frog. It is unlikely that if either 'Mary left the milk' or 'Brian is a frog' but not both then Greg is a lion. It is unlikely that if 'Mary left the milk and Brian is a frog' then Jeff put down the milk. It is almost certain that if 'Julius is white' or 'Brian is a frog' or both then John went to the hallway.
We doubt that 'Jeff put down the milk' or 'Greg is a lion' or both.
We doubt that 'Jeff put down the milk' or 'Greg is a lion' or both.
It is highly likely that 'Jeff put down the milk' or 'Greg 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
  0.1::factA.
  0.5::factB.
  0.6::factC.
  %hop1
  0.2::factX:-xor(factB,factC).
  0.2::factY:-and(factB,factC).
  0.95::factZ:-or(factA,factC).

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

  query(conclusion).
  
'Jeff put down the milk' or 'Greg is a lion' or both.