There is a very good chance that Greg is a swan. It is likely that Sandra got the football. It is probable that Brian is a swan. We believe that if 'Sandra got the football' or 'Brian is a swan' or both then Mary dropped the apple. It is unlikely that if 'Sandra got the football' or 'Greg is a swan' or both then John went to the kitchen. It is probably the case that if 'Brian is a swan and Greg is a swan' then Lily is a rhino.
It is impossible that 'Lily is a rhino and Greg is a swan'.
Chances are about even that 'Lily is a rhino and Greg is a swan'.
It is impossible that 'Lily is a rhino and Greg 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
  0.8::factA.
  0.7::factB.
  0.7::factC.
  %hop1
  0.75::factX:-or(factB,factC).
  0.2::factY:-or(factB,factA).
  0.7::factZ:-and(factC,factA).

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

  query(conclusion).
  
'Lily is a rhino and Greg is a swan'.