There is a better than even chance that John left the football. It is impossible that Bernhard is a swan. We doubt that Jeff went to the hallway. Chances are slight that if 'Bernhard is a swan and Jeff went to the hallway' then Julius is yellow. There is a very good chance that if 'Bernhard is a swan and Jeff went to the hallway' then Lily is green. It is probable that if 'John left the football' or 'Jeff went to the hallway' or both then Sandra dropped the milk.
It is likely that 'Jeff went to the hallway and Bernhard is a swan'.
It is impossible that 'Jeff went to the hallway and Bernhard is a swan'.
It is likely that 'Jeff went to the hallway and Bernhard is a swan'.

  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
  0.6::factA.
  0.0::factB.
  0.2::factC.
  %hop1
  0.1::factX:-and(factB,factC).
  0.8::factY:-and(factB,factC).
  0.7::factZ:-or(factA,factC).

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

  query(conclusion).
  
'Jeff went to the hallway and Bernhard is a swan'.