Places, cuts and orderings of function fields

Abstract

In this paper we investigate the space of R-places of an algebraic function field of one variable. We deal with the problem of determining when two orderings of such a field correspond to a single R-place. To this end we introduce and study the space of cuts on a real curve and prove that the space is homeomorphic to the space of orderings. Finally, we prove that two cuts (consequently, two orderings) correspond to a single R-place if they are induced by a single ultrametric ball.