Theorems in discrete geometry

Discrete geometry is a branch of geometry that studies geometric objects and properties in a combinatorial or discrete context. It often involves finite sets of points, polygons, polyhedra, and other shapes, and focuses on their combinatorial and topological properties. Theorems in discrete geometry often relate to the arrangement, selection, or structure of these sets in specific ways.

Beck's theorem, in the context of geometry, generally refers to a result in the field of combinatorial geometry related to point sets and convex shapes. More specifically, it states that for any finite set of points in the plane, there exists a subset of those points that can be covered by a convex polygon of a certain size, where the size is influenced by the dimension of the space.

Carathéodory's theorem is a fundamental result in convex geometry that characterizes the representation of points in a convex set.

De Bruijn's theorem, named after the Dutch mathematician Nicolaas Govert de Bruijn, is primarily known in the context of combinatorics and graph theory. It refers to several important results, but the most widely recognized version is in relation to the properties of sequences and combinatorial structures.

The Erdős–Anning theorem is a result in the field of combinatorial number theory, particularly concerning sequences of integers and their properties regarding sums and subsets. Specifically, the theorem addresses the characterization of sequences that can avoid certain types of linear combinations.

The Erdős–Nagy theorem is a result in number theory that describes the conditions under which certain sequences can be generated by the marks made during a specific iterative process involving integers. More specifically, it concerns the distribution of sums of subsets of natural numbers. The theorem states that if \( A \) is a set of natural numbers, then the set of all finite sums formed by taking elements from \( A \) has certain properties related to density.

The Four-Vertex Theorem is a result in differential geometry and the study of curves. It states that for a simple, closed, smooth curve in the plane (which means a curve that does not intersect itself and is continuously differentiable), there are at least four distinct points at which the curvature of the curve attains a local maximum or minimum. To elaborate, curvature is a measure of how sharply a curve bends at a given point.

Helly's theorem is a result in combinatorial geometry that deals with the intersection of convex sets in Euclidean space. The theorem provides a condition for when the intersection of a collection of convex sets is non-empty.

Kirchberger's theorem pertains to the field of mathematics, specifically in the area of graph theory and combinatorial optimization. The theorem is often involved with properties of vertices and edges in graphs, particularly in relation to specific configurations or arrangements. However, it’s important to note that Kirchberger's theorem is not as widely known as some other mathematical theorems, so detailed and widely recognized references might be limited.

The Krein–Milman theorem is a fundamental result in convex analysis and functional analysis, particularly dealing with convex sets in the context of topological vector spaces. The theorem essentially provides a characterization of convex compact sets.

Monsky's theorem is a result in geometry related to the dissection of polygons. It states that it is impossible to dissect a square into a finite number of pieces, each of which is congruent to a given triangle with an odd area.

Radon's theorem is a result in convex geometry that deals with the intersection of convex sets. Specifically, it states that: **Radon's Theorem:** If a set of \( d + 2 \) points in \( \mathbb{R}^d \) is given, then it is possible to partition these points into two non-empty subsets such that the convex hulls (the smallest convex sets containing the points) of these two subsets intersect.

Tverberg's theorem is a result in combinatorial geometry that concerns the division of points in Euclidean space. It states that for any set of \( (r-1)(d+1) + 1 \) points in \( \mathbb{R}^d \), it is possible to partition these points into \( r \) groups such that the \( r \) groups share a common point in their convex hulls.

The Wallace–Bolyai–Gerwien theorem is a result in geometry related to the transformation of polygons. Specifically, it states that any two simple polygons of equal area can be dissected into a finite number of polygonal pieces that can be rearranged to form one another. The theorem has important implications in the study of geometric dissections, a topic that has intrigued mathematicians for centuries.