Semialgebraic and Continuous Solution of Linear Equations with Semialgebraic Coefficients

Abstract

Starting from the results of Charles Fefferman and Janos Kollár in \texit{Continuous Solutions of Linear Equations} [1], we adopt a new approach based on Fefferman's techniques of Glaeser refinement to show a more general result than the one proved by Kollár by using techniques from algebraic geometry. Considering a system of linear equations with semialgebraic (not only polynomial as in [1]) coefficients on ${\mathbb{R}}^n$, we get a necessary and sufficient condition for the existence of a continuous and semialgebraic solution on ${\mathbb{R}}^n$. This is different from what Fefferman and Luli obtained in \textit{Semialgebraic Sections Over the Plane} since they stated their result for solutions of regularity $C^m$ on the plane ${\mathbb{R}}^2$. More in depth, we prove that a continuous and semialgebraic solution on ${\mathbb{R}}^n$ exists if and only if there is a continuous solution i.e., if the Glaeser-stable bundle associated to the system has no empty fiber.

arXiv comment12 pages. arXiv admin note: text overlap with arXiv:2005.00067