prop_outerAntisymmetry x y =
 isVector x && isVector y && (x /= y) ==> c == - c'
    where c  :* _ = x `out` y
          c' :* _ = y `out` x
prop_outerAntisymmetry x y =
 isVector x && isVector y && (x /= y) ==> c == - c'
    where c  :* _ = x `out` y
          c' :* _ = y `out` x
prop_outerAntisymmetry x y =
 isVector x && isVector y && (x /= y) ==> c == - c'
    where c  :* _ = x `out` y
          c' :* _ = y `out` x