Chances are slight that Emily is a sheep. We believe that Bernhard is a rhino. It is impossible that Greg is a frog. It is probable that if 'Greg is a frog and Emily is a sheep' then John moved to the garden. Chances are slight that if 'Greg is a frog and Emily is a sheep' then Brian is white. There is almost no chance that if 'Bernhard is a rhino' or 'Greg is a frog' or both then Mary went to the bedroom.
It is certain that 'John moved to the garden' or 'Brian is white' or both.
It is impossible that 'John moved to the garden' or 'Brian is white' or both.
It is certain that 'John moved to the garden' 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
  0.1::factA.
  0.75::factB.
  0.0::factC.
  %hop1
  0.7::factX:-and(factC,factA).
  0.1::factY:-and(factC,factA).
  0.02::factZ:-or(factB,factC).

  %hop2
  conclusion:-or(factX,factY).

  query(conclusion).
  
'John moved to the garden' or 'Brian is white' or both.