Chances are slight that Brian is a swan. We believe that Bernhard is a frog. Chances are slight that Sandra got the milk. It is probably not the case that if 'Brian is a swan and Bernhard is a frog' then Lily is white. It is likely that if 'Sandra got the milk and Brian is a swan' then Yann is hungry. There is a very good chance that if 'Bernhard is a frog and Sandra got the milk' then Jeff went to the bedroom.
There is a very good chance that 'Jeff went to the bedroom and Yann is hungry'.
It is impossible that 'Jeff went to the bedroom and Yann is hungry'.
There is a very good chance that 'Jeff went to the bedroom and Yann is hungry'.

  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.
  0.75::factB.
  0.1::factC.
  %hop1
  0.25::factX:-and(factA,factB).
  0.7::factY:-and(factC,factA).
  0.8::factZ:-and(factB,factC).

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

  query(conclusion).
  
'Jeff went to the bedroom and Yann is hungry'.