Fractional Laplace operator on finite graphs

Nowadays a great attention has been focused on the discrete fractional Laplace operator as the natural counterpart of the continuous one. In this paper, we discretize the fractional Laplace operator $(-\Delta)^{s}$ for an arbitrary finite graph and any positive real number $s$. It is shown that $(-\Delta)^{s}$ can be explicitly represented by eigenvalues and eigenfunctions of the Laplace operator $-\Delta$. Moreover, we study its important properties, such as $(-\Delta)^{s}$ converges to $-\Delta$ as $s$ tends to $1$; while $(-\Delta)^{s}$ converges to the identity map as $s$ tends to $0$ on a specific function space. For related problems involving the fractional Laplace operator, we consider the fractional Kazdan-Warner equation and obtain several existence results via variational principles and the method of upper and lower solutions.