Homogeneous Systems and Euclidean Topology

TL;DR

This paper explores the invariance of domain theorem using algebraic and topological methods, connecting it to fundamental results in analysis and employing the Borsuk-Ulam theorem with algebraic independence considerations.

Contribution

It provides a novel proof of the invariance of domain theorem leveraging algebraic independence and the Borsuk-Ulam theorem, emphasizing an ideal-theoretic approach.

Findings

Proof of invariance of domain using algebraic methods

Connection between Borsuk-Ulam theorem and topological invariance

Application of algebraic independence in topological proofs

Abstract

The Theorem on Invariance of Domain due to L.E.J. Brouwer states that one connected, compact (Hausdorff) m-dimensional manifold embedded into another actually realizes a homeomorphism. This fundamental result is relevant to Functional Analysis, as the classical Gelfand-Mazur Theorem, as well as the real form of the Fundamental Theorem of Algebra, can both be derived easily from it. Our main tool is the m-dimensional borsuk-Ulam Theorem: a certain real vector must be found, which is established by means of solving a real homogeneous system of equations as in the Theorem of Be'zout. We emphasize the ideal-theoretic approach to the latter, based on work of Kapferer and vander Waerden from the 1920s. A modern explanation combines resultant- and non-resultant oriented methods in projective geometry. The technical point involves algebraic independence (over the rational numbers) of the System coefficients. Invariance of Domain follows from the fact that on a sphere, "any odd mapping is essential" (B-U), as well as "an injection of a ball is homotopic to an odd mapping". This homotopy avoids a neighborhood of the Origin, giving the required open set at the Origin of the image ball.