Construction of discrete analogue of the differential operator   $\frac{d^4}{dx^4}+2\frac{d^2}{dx^2}+1$ and its properties
  In the present paper the discrete analogue of the differential operator $\frac{d^4}{dx^4}+2\frac{d^2}{dx^2}+1$ is constructed and its some properties are proved. 
A.R. Hayotov
math.NA