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Quasi-homeomorphisms, Goldspectral spaces and Jacspectral spaces

Othman Echi (2003)

Bollettino dell'Unione Matematica Italiana

In this paper, we deal with the study of quasi-homeomorphisms, the Goldman prime spectrum and the Jacobson prime spectrum of a commutative ring. We prove that, if g : Y X is a quasi-homeomorphism, Z a sober space and f : Y Z a continuous map, then there exists a unique continuous map F : X Z such that F g = f . Let X be a T 0 -space, q : X s X the injection of X onto its sobrification X s . It is shown, here, that q Gold X = Gold X s , where Gold X is the set of all locally closed points of X . Some applications are also indicated. The Jacobson prime spectrum...

Real holomorphy rings and the complete real spectrum

D. Gondard, M. Marshall (2010)

Annales de la faculté des sciences de Toulouse Mathématiques

The complete real spectrum of a commutative ring A with 1 is introduced. Points of the complete real spectrum Sper c A are triples α = ( 𝔭 , v , P ) , where 𝔭 is a real prime of A , v is a real valuation of the field k ( 𝔭 ) : = qf ( A / 𝔭 ) and P is an ordering of the residue field of v . Sper c A is shown to have the structure of a spectral space in the sense of Hochster [5]. The specialization relation on Sper c A is considered. Special attention is paid to the case where the ring A in question is a real holomorphy ring.

Relatively complete ordered fields without integer parts

Mojtaba Moniri, Jafar S. Eivazloo (2003)

Fundamenta Mathematicae

We prove a convenient equivalent criterion for monotone completeness of ordered fields of generalized power series [ [ F G ] ] with exponents in a totally ordered Abelian group G and coefficients in an ordered field F. This enables us to provide examples of such fields (monotone complete or otherwise) with or without integer parts, i.e. discrete subrings approximating each element within 1. We include a new and more straightforward proof that [ [ F G ] ] is always Scott complete. In contrast, the Puiseux series field...

Representations of non-negative polynomials having finitely many zeros

Murray Marshall (2006)

Annales de la faculté des sciences de Toulouse Mathématiques

Consider a compact subset K of real n -space defined by polynomial inequalities g 1 0 , , g s 0 . For a polynomial f non-negative on K , natural sufficient conditions are given (in terms of first and second derivatives at the zeros of f in K ) for f to have a presentation of the form f = t 0 + t 1 g 1 + + t s g s , t i a sum of squares of polynomials. The conditions are much less restrictive than the conditions given by Scheiderer in [11, Cor. 2.6]. The proof uses Scheiderer’s main theorem in [11] as well as arguments from quadratic form theory...

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