A Jordan Curve Theorem for 2-dimensional Tilings

The classical Jordan curve theorem for digital curves asserts that the Jordan curve theorem remains valid in the Khalimsky plane. Since the Khalimsky plane is a quotient space of ${\mathbb{R}}^2$ induced by a tiling of squares, it is natural to ask for which other tilings of the plane it is possible to obtain a similar result. In this paper we prove a Jordan curve theorem which is valid for every locally finite tiling of ${\mathbb{R}}^2$. As a corollary of our result, we generalize some classical Jordan curve theorems for grids of points, including Rosenfeld’s theorem.