Semi-local lattices
An -module has an almost trivial dual if there are no epimorphisms from to the free -module of countable infinite rank . For every natural number , we construct arbitrarily large separable -free -modules with almost trivial dual by means of Shelah’s Easy Black Box, which is a combinatorial principle provable in ZFC.
Experience shows that in geometric situations the separating ideal associated with two orderings of a ring measures the degree of tangency of the corresponding ultrafilters of semialgebraic sets. A related notion of separating ideals is introduced for pairs of valuations of a ring. The comparison of both types of separating ideals helps to understand how a point on a surface is approached by different half-branches of curves.
Nous nous intéressons ici essentiellement à l’algèbre de Hadamard des séries formelles. Si des résultats importants ont été obtenus dans le cas d’une variable, il n’en est pas de même dans le cas de plusieurs variables. En effet, beaucoup de problèmes posés restent encore sans réponse. C’est le cas par exemple du problème du quotient de Hadamard, ou celui de la caractérisation des éléments de Hadamard inversibles, ou les diviseurs de zéro, ou encore le problème des multiplicateurs de certains sous-ensembles...
This short note is a continuation of and and its purpose is to show that every simple zeropotent paramedial groupoid containing at least three elements is strongly balanced in the sense of .
On démontre que toute solution formelle d’un système d’équations analytiques réelles (resp. polynomiales réelles) , se relève en une solution homotope à une solution analytique (resp. à une solution de Nash) aussi proche que l’on veut de pour la topologie de Krull. On utilise ce théorème pour démontrer l’algébricité (ou l’analyticité) de certains idéaux de (ou ), et aussi pour construire des déformations analytiques de germes d’ensembles analytiques en germes d’ensembles de Nash.
We study the effect of changing the residue field, on the topological properties of local algebra homomorphisms of analytic algebras (quotients of convergent power series rings). Although injectivity is not preserved, openness and closedness in the Krull topology, simple topology, and inductive topology is preserved.
Let (U) denote the algebra of holomorphic functions on an open subset U ⊂ ℂⁿ and Z ⊂ (U) its finite-dimensional vector subspace. By the theory of least spaces of de Boor and Ron, there exists a projection from the local ring onto the space of germs of elements of Z at b. At a general point b ∈ U its kernel is an ideal and induces the structure of an Artinian algebra on . In particular, this holds at points where the kth jets of elements of Z form a vector bundle for each k ∈ ℕ. For an embedded...
The notion of a real semigroup was introduced in [8] to provide a framework for the investigation of the theory of (diagonal) quadratic forms over commutative, unitary, semi-real rings. In this paper we introduce and study an outstanding class of such structures, that we call spectral real semigroups (SRS). Our main results are: (i) The existence of a natural functorial duality between the category of SRSs and that of hereditarily normal spectral spaces; (ii) Characterization of the SRSs as the...