On Rings admitting orderings and 2-primary chains of orderings of higher level.
On the Pierce-Birkhoff Conjecture for Smooth Affine Surfaces over Real Closed Fields
We will prove that the Pierce-Birkhoff Conjecture holds for non-singular two-dimensional affine real algebraic varieties over real closed fields, i.e., if is such a variety, then every piecewise polynomial function on can be written as suprema of infima of polynomial functions on . 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.