Any function field "K"("V") of an algebraic variety "V" over "K", other than a single point, has a subfield isomorphic with "K"("T"). From the point of view of birational geometry, this means that there will be a rational map from "V" to P1("K"), that is not constant. The image will omit only finitely many points of P1("K"), and the inverse image of a typical point "P" will be of dimension . This is the beginning of methods in algebraic geometry that are inductive on dimension. The rational maps play a role analogous to the meromorphic functions of complex analysis, and indeed in the case of compact Riemann surfaces the two concepts coincide.