Below is the graph of a quadratic function, showing where the function is increasing and decreasing. If we draw in the tangents to the curve, you will notice that if the gradient of the tangent is ...

We study the Dirichlet problem for discrete harmonic functions in unbounded product domains on multidimensional lattices. First we prove some versions of the Phragmén-Lindelöf theorem and use Fourier ...

In this paper we prove the following theorem: let G be a discrete amenable group with nontrivial almost-periodic compactification, and let F be a complex-valued function defined in [-1, 1]; then F ...