dc.description.abstract | For $2\le N\in \N$ and $\G_i\in \R\setminus\{0\}$ we proof that functions of the form
$$
H_\G (p_1,\dots, p_N) = \sum_{i\ne j} \G_i\G_j G(p_i,p_j) + \sum_{i=1}^N \G_i^2 R(p_i) ,
$$
admit critical points under various circumstances. The $p_i$ will either belong to an open, bounded subset $\gO\subset \R^d$ with smooth boundary for $d \ge 3$ or to a compact, two dimensional, riemanian manifold $(\gS ,g )$. Furthermore, $G$ is a (Dirichlet) Green's function of the negative Laplacian $-\gD$ associated to $\gO$ or $(\gS, g)$ and $R$ is its Robin's function.\\
For the case of an open set, we also consider the function $\gr$ that is the least eigenvalue of the matrix
$$
(M(x_1,\dots,x_N))_{i,j=1}^N := \begin{cases}
-G(x_i , x_j),& i\ne j\\
R(x_i),& i=j .
\end{cases}
$$
To achieve the critical points, we also calculate appropriate approximations of the Green's function and Robin's function when close to their singularities. | de_DE |