We doubt that Winona is a sheep. There is a better than even chance that Greg is gray. It is certain that Sandra left the football. It is likely that if 'Winona is a sheep and Sandra left the football' then Gertrude is a cat. It is certain that if either 'Winona is a sheep' or 'Sandra left the football' but not both then Julius is white. It is highly unlikely that if 'Winona is a sheep' or 'Greg is gray' or both then Bernhard is a frog.
We believe that 'Gertrude is a cat and Bernhard is a frog'.
It is impossible that 'Gertrude is a cat and Bernhard is a frog'.
We believe that 'Gertrude is a cat and Bernhard is a frog'.

  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
  0.2::factA.
  0.6::factB.
  1.0::factC.
  %hop1
  0.7::factX:-and(factA,factC).
  1.0::factY:-xor(factA,factC).
  0.05::factZ:-or(factA,factB).

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

  query(conclusion).
  
'Gertrude is a cat and Bernhard is a frog'.