It is certain that Lily is a swan. There is a better than even chance that Gertrude is a mouse. We believe that Fred put down the apple. Chances are slight that if either 'Gertrude is a mouse' or 'Fred put down the apple' but not both then Brian is green. It is impossible that if 'Lily is a swan' or 'Fred put down the apple' or both then Mary dropped the milk. It is probably the case that if 'Fred put down the apple and Gertrude is a mouse' then Jessica is a cat.
It is improbable that 'Lily is a swan and Fred put down the apple'.
We believe that 'Lily is a swan and Fred put down the apple'.
It is improbable that 'Lily is a swan and Fred put down 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
  1.0::factA.
  0.6::factB.
  0.75::factC.
  %hop1
  0.1::factX:-xor(factB,factC).
  0.0::factY:-or(factA,factC).
  0.7::factZ:-and(factC,factB).

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

  query(conclusion).
  
'Lily is a swan and Fred put down the apple'.