  Determining if an (1+1)-differential-difference equation is integrable or not
(in the sense of possessing an infinite number of symmetries) can be reduced to
the study of the dependence of the equation on the lattice points, according to
Yamilov's theorem. We shall apply this result to a class of
differential-difference equations obtained as partial continuous limits of
3-points difference equations in the plane and conclude that they cannot be
integrable.
