Información del autor
Autor Ruiz Sancho, Jesús María |
Documentos disponibles escritos por este autor (73)
![](./images/expand_all.gif)
![](./images/collapse_all.gif)
![Selecciones disponibles](./images/orderby_az.gif)
![]()
texto impreso
Acquistapace, Francesca ; Broglia, Fabrizio ; Fernando Galván, José Francisco ; Ruiz Sancho, Jesús María | Société Mathématique de France | 2005We show that (i) every positive semidefinite meromorphic function germ on a surface is a sum of 4 squares of meromorphic function germs, and that (ii) every positive semidefinite global meromorphic function on a normal surface is a sum of 5 squa[...]![]()
texto impreso
We present here some applications of the theory of real spectra of excellent rings to the ring of global analytic functions on a compact real analytic manifold. Section 1 contains the facts of the theory that shall be used in the sequel. Section[...]![]()
texto impreso
Let M be a real analytic manifold and O(M) its ring of global analytic functions. Let Z be a global semianalytic set of M (that is, a subset of M of the form Z=?r i=0{x?M:fi1 (x)> 0,?,fis (x)> 0, gi (x)=0}, where fij,gi?O(M)). In this paper, the[...]![]()
texto impreso
After describing explicitly all total orderings in the ring R[[x,y]], we prove that each ordering in the quotient field of the ring of germs of real analytic functions at an irreducible point O of a real analytic surface X is defined by a half-b[...]![]()
texto impreso
We show that any positive semidefinite analytic function germ on the cone z(2) = x(2) + y(2) is a sum of two squares of analytic function germs.![]()
texto impreso
This is a research survey on results dealing with the following question: Let M be a compact smooth manifold and A a family of geometric objects related to M such that there exists some natural equivalence of the pairs (M,A). Does every equivale[...]![]()
texto impreso
Este trabajo es una revisión de la historia y las soluciones de los problemas básicos globales de las funciones de Nash que se han resuelto recientemente: separación, extensión, ecuaciones globales, representación de Artin-Mazur e idempotencia![]()
texto impreso
Let k be a real closed field. A real curve germ over k is a real one-dimensional Noetherian local integral domain with residual field k. A Noetherian local ring A with maximal ideal m and completion  is an AP-ring if for every system of polynom[...]![]()
texto impreso
Let K be a formally real field and ? its order space. The automorphisms group of K acts on ?, and K is called D.O.P. when all the orbits are dense in ?. In this note the following is shown: The field of meromorphic function germs of a real irred[...]![]()
texto impreso
![]()
texto impreso
In this talk I shall discuss the notion and some basic features of semialgebraic and semianalytic sets, which are one main concern of Real Geometry![]()
texto impreso
Gascón, Francisco G. ; Peralta Salas, Daniel ; Ruiz Sancho, Jesús María | American Institute of Physics | 2000-05It is shown that when a dynamical system X0 with a proper set of global first integrals is perturbed, the phase space region accessible to the orbits of the perturbed vector field X0+Xp is bounded (we are assuming here that the time variable run[...]![]()
texto impreso
Nash functions are those real analytic functions which are algebraic over the polynomials. Let M?Rn be a Nash manifold, N(M) the ring of Nash functions on M and O(M) the ring of analytic functions on M. The following problems have been open for [...]![]()
texto impreso
We obtain some results (a Nullstellensatz, a specialization theorem, `à la E. Artin') for Nash algebras with an algebraic method based on M. Artin's theorem (and easily generalizable to the analytic case) notably simplifying known proofs![]()
texto impreso
Alonso García, María Emilia ; Etayo Gordejuela, J. Javier ; Gamboa, J. M. ; Ruiz Sancho, Jesús María | Real Sociedad Matemática Española;Consejo Superior de Investigaciones Científicas. Instituto "Jorge Juan" de Matemáticas | 1980Dado un espacio T3? (X,T), es posible obtener una compactificación T2 del mismo, mediante ultrafiltros asociados a ciertas bases distinguidas de cerrados de (X,T) (Frink [4]). Se plantea así el problema siguiente: ¿Puede obtenerse toda compactif[...]