Chances are about even that John went to the hallway. It is impossible that Sandra put down the milk. It is highly likely that Julius is a frog. It is highly likely that if 'John went to the hallway and Julius is a frog' then Sumit is hungry. It is almost certain that if 'Sandra put down the milk' or 'Julius is a frog' or both then Greg is green. There is little chance that if 'John went to the hallway' or 'Julius is a frog' or both then Bernhard is white.
We believe that 'Sandra put down the milk and John went to the hallway'.
It is impossible that 'Sandra put down the milk and John went to the hallway'.
We believe that 'Sandra put down the milk and John went to the hallway'.

  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
  0.5::factA.
  0.0::factB.
  0.9::factC.
  %hop1
  0.9::factX:-and(factA,factC).
  0.95::factY:-or(factB,factC).
  0.1::factZ:-or(factA,factC).

  %hop2
  conclusion:-and(factB,factA).

  query(conclusion).
  
'Sandra put down the milk and John went to the hallway'.