It is highly unlikely that Julius is a swan. There is a very good chance that Bernhard is green. We believe that John picked up the milk. It is highly unlikely that if 'Julius is a swan and John picked up the milk' then Mary went to the office. It is impossible that if 'Julius is a swan' or 'John picked up the milk' or both then Sandra dropped the apple. It is almost certain that if 'John picked up the milk and Bernhard is green' then Jeff left the apple.
It is likely that 'John picked up the milk and Sandra dropped the apple'.
It is impossible that 'John picked up the milk and Sandra dropped the apple'.
It is likely that 'John picked up the milk and Sandra dropped the apple'.

  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.
  0.8::factB.
  0.75::factC.
  %hop1
  0.05::factX:-and(factA,factC).
  0.0::factY:-or(factA,factC).
  0.95::factZ:-and(factC,factB).

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

  query(conclusion).
  
'John picked up the milk and Sandra dropped the apple'.