We believe that Mary took the football. There is almost no chance that John moved to the office. There is almost no chance that Winona is a sheep. There is almost no chance that if 'Winona is a sheep' or 'Mary took the football' or both then Gertrude is a cat. It is highly unlikely that if 'Winona is a sheep' or 'John moved to the office' or both then Brian is a rhino. It is almost certain that if 'John moved to the office and Mary took the football' then Greg is white.
It is certain that 'Gertrude is a cat and Winona is a sheep'.
It is impossible that 'Gertrude is a cat and Winona is a sheep'.
It is certain that 'Gertrude is a cat and Winona is a sheep'.

  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.
  0.02::factB.
  0.02::factC.
  %hop1
  0.02::factX:-or(factC,factA).
  0.05::factY:-or(factC,factB).
  0.95::factZ:-and(factB,factA).

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

  query(conclusion).
  
'Gertrude is a cat and Winona is a sheep'.