We believe that Brian is white. It is impossible that Greg is a rhino. Chances are about even that Lily is a rhino. It is impossible that if 'Lily is a rhino and Brian is white' then John went to the kitchen. It is probable that if 'Brian is white and Greg is a rhino' then Bill moved to the office. Chances are slight that if 'Greg is a rhino and Lily is a rhino' then Fred put down the apple.
We doubt that 'Fred put down the apple' or 'Brian is white' or both.
We believe that 'Fred put down the apple' or 'Brian is white' or both.
We doubt that 'Fred put down the apple' or 'Brian is white' or both.

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

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

  query(conclusion).
  
'Fred put down the apple' or 'Brian is white' or both.