On Algebraicity of Global Real Analytic Sets and Functions
The group of real analytic diffeomorphisms of a real analytic manifold is a rich group. It is dense in the group of smooth diffeomorphisms. Herman showed that for the -dimensional torus, its identity component is a simple group. For fibered manifolds, for manifolds admitting special semi-free actions and for 2- or 3-dimensional manifolds with nontrivial actions, we show that the identity component of the group of real analytic diffeomorphisms is a perfect group.
The space S of all non-trivial real places on a real function field K|k of trascendence degree one, endowed with a natural topology analogous to that of Dedekind and Weber's Riemann surface, is shown to be a one-dimensional k-analytic manifold, which is homeomorphic with every bounded non-singular real affine model of K|k. The ground field k is an arbitrary ordered, real-closed Cantor field (definition below). The function field K|k is thereby represented as a field of real mappings of S which might...
Soit l’algèbre des fonctions sur engendrée par les fonctions polynomiales et les exponentielles de formes linéaires. La partie de appartient à si et seulement s’il existe et dans pour lesquels est l’image par la projection canonique de sur , de l’ensemble des zéros de . Soit le plus petit sous-ensemble de parties de qui contient , l’adhérence de ses éléments et les images par la projection canonique de qui contient , l’adhérence de ses éléments et les images par la...
We prove that the ring ℝ[M] of all polynomials defined on a real algebraic variety is dense in the Hilbert space , where dμ denotes the volume form of M and the Gaussian measure on M.