Three-Dimensional Polyhedra Can Be Described by Three Polynomial Inequalities

Abstract

Bosse et al. conjectured that for every natural number d≥2 and every d-dimensional polytope P in ℝ d , there exist d polynomials p 1(x),…,p d (x) satisfying P={x∈ℝd :p 1(x)≥0,…,p d (x)≥0}. We show that every three-dimensional polyhedron can be described by three polynomial inequalities, which confirms the conjecture for the case d=3 but also provides an analogous statement for the case of unbounded polyhedra. The proof of our result is constructive.