2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/221259We will prove that the Pierce-Birkhoff Conjecture holds for non-singular two-dimensional affine real algebraic varieties over real closed fields, i.e., if W is such a variety, then every piecewise polynomial function on W can be written as suprema of infima of polynomial functions on W. More precisely, we will give a proof of the so-called Connectedness Conjecture for the coordinate rings of such varieties, which implies the Pierce-Birkhoff Conjecture.v2: Removed typos, changed content. v3: Added missing conditions for several results in section 6Algebraic GeometryCommutative Algebratext