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WALTER DE GRUYTER |
Documentos disponibles de esta editorial (24)
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A semialgebraic set is called basic if it can be described by a single system of strict polynomial inequalities. A semianalytic set is called basic if it can be described by a system of strict real analytic inequalities in a neighborhood of each[...]texto impreso
We prove that every dense subgroup of a topological abelian group has the same ‘convergence dual’ as the whole group. By the ‘convergence dual’ we mean the character group endowed with the continuous convergence structure. We draw as a corollary[...]texto impreso
From the introduction: Let $X\subset\bbfP^n$ be a non-degenerate degree $d$ variety over the field of complex numbers, which is ruled by $k$-planes over a curve. Let us also suppose that there is no point of $X$ such that all the rules pass thro[...]texto impreso
A finite-dimensional complex Lie algebra g is characteristically nilpotent if its Lie algebra Derk(g) of derivations is nilpotent. Given two finite-dimensional nilpotent Lie algebras g1, g2, the authors construct a non-split central extension g1[...]texto impreso
Let G(r,m) denote the Grassmann variety of r-dimensional linear subspaces of Pm. To any linear projection Pm?Pm?, m?texto impreso
We give a complete classification of smooth congruences - i.e. surfaces in the Grassmann variety of lines in P 3C identified with a smooth quadric in P5- of degree at most 8, by studying which surfaces of P5can lie in a smooth quadric and provin[...]texto impreso
Let X subset of R-n be a real analytic manifold of dimension 2. We study the stability index of X, s(X), that is the smallest integer s such that any basic open subset of X can be written using s global analytic functions. We show that s(X) = 2 [...]texto impreso
Let M be a connected paracompact real analytic manifold and S a semi-analytic subset. The following results are proved: 1) If dim(M) = 2 and S is globally semianalytic, then every connected component of S is again globally semianalytic. 2) S is [...]texto impreso
The aim of the present study was to examine the effect of preparation on the characteristics of imagined and perceptual memory descriptions. Following recent research (Alonso?Quecuty, 1990; Suengas & Johnson, 1988) it was hypothesized that subj[...]texto impreso
For a topological abelian group X we topologize the group c0(X) of all X-valued null sequences in a way such that when X= the topology of c0() coincides with the usual Banach space topology of the classical Banach space c0. If X is a non-trivial[...]texto impreso
Monte Lara, María Concepción ; MacNeil, Donald ; Negro Álvarez, Carlos Manuel ; Blanco Suárez, Ángeles | WALTER DE GRUYTER | 2010Mixtures of stickies-containing and stickies-free pulps were investigated for their deposition potntial in an attempt to better understand the interactions of dissolved and colloidal material (DCM) when mixing two different pulps. The filtered p[...]texto impreso
In the paper under review, the authors study the jets of antimulticanonical bundles on certain del Pezzo surfaces. The main idea is to investigate the stratification of the surfaces given by the rank of the evaluation map with values in the seco[...]texto impreso
In this work we introduce the definition of Schwarzenberger bundle on a Grassmannian. Recalling the notion of Steiner bundle, we generalize the concept of jumping pair for a Steiner bundle on a Grassmannian. After studying the jumping locus vari[...]texto impreso
K?kol, Jerzy ; López Pellicer, Manuel ; Martín Peinador, Elena ; Tarieladze, Vaja | WALTER DE GRUYTER | 2008Theorem 1 proves (among the others) that for a locally compact topological group X the following assertions are equivalent: (i) X is metrizable and sigma-compact. (ii) C-p(X) is analytic. (iii) C-p(X) is K-analytic. (iv) C-p(X) is Lindelof. (v) [...]texto impreso
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In this paper we study the normal bundle of the embedding of subvarieties of dimension n - 1 in the Grassmann variety of lines in P(n). Making use of some results on the geometry of the focal loci of congruences ([4] and [5]), we give some crite[...]texto impreso
Lie algebra model theory studies the closure O() of the Gln(C)-orbit in the variety Ln of Lie algebra laws of a law on Cn using nonstandard analysis. In this context, given a Lie algebra law , a contraction of is a law ? with ? 2 O(). On the o[...]texto impreso
We compute the ?rst and second cohomology groups with coe?cients in the adjoint module of frobeniusian model algebras whose parameters move in a dense open subset of C p?1, and obtain upper bounds for the dimension of cohomology groups of froben[...]texto impreso
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In this work we study the Positive Extension (pe) property and Hilbert's 17th problem for real analytic germs and sets. A real analytic germ X-0 of R-0(n) has the pe property if every positive semidefinite analytic function germ on X-0 has a pos[...]texto impreso
In this work we develop new techniques to compute Koszul cohomology groups for several classes of varieties. As applications we prove results on projective normality and syzygies for algebraic surfaces. From more general results we, obtain in pa[...]texto impreso
We give the list of all possible smooth congruences in G(1,n) which have a quadric bundle structure over a curve and we explicitely construct most of them.texto impreso
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Andradas Heranz, Carlos ; Díaz-Cano Ocaña, Antonio ; Ruiz Sancho, Jesús María | WALTER DE GRUYTER | 2003We solve the 17th Hilbert Problem and prove the Artin-Lang property for normal real analytic surfaces. Then we deduce that the absolute (resp. relative) holomorphy ring of such a surface consists of all bounded (resp. locally bounded) meromorphi[...]