On energy functionals for second-order elliptic systems with constant coefficients

Abstract

We consider the Dirichlet problem for second-order elliptic systems with constant coefficients. We prove that non-reducible strongly elliptic systems of this type do not admits non-negatively defined energy functionals of the form $f\mapsto {\int }_D\Phi (u_x,v_x,u_y,v_y)dxdy$, where $D$ is the domain where the problem we are interested in is considered, $\Phi$ is some quadratic form in ${\mathbb{R}}^4$, and $f=u+iv$ is a function in the complex variable. The proof is based on reducing the system under consideration to a special (canonical) form, when the differential operator defining this system is represented as a perturbation of the Laplace operator with respect to two small real parameters (the canonical parameters of the system under consideration).

arXiv comment12 pages