Hypersphere-Based Restricting Conditions for Colorings of the Euclidean Space
Gabriel Istrate, Catalin Zara
Abstract
We investigate colorings of the Euclidean space \(\mathbb{R}^n\) in which the color of a point \(p\) is determined by monochromatic configurations of points lying on hyperspheres centered at \(p\). We consider two types of conditions: those based on the cardinality of the forcing sets and admissible radii, and those based on certain geometric properties of simplices, such as shape, edge lengths, or volumes, for colorings using countably (finite or infinite) many colors. Our main objective is to determine whether a given condition forces the coloring to be monochromatic or not. Examples constructed using existing results show that, for conditions based on shapes, additional regularity assumptions on color classes are necessary. Accordingly, we study colorings that are somewhere comeager.
