The Grade of an M-ideal
نویسنده
چکیده
We assign two parameters to an M-ideal J in a Ba-nach space X, called the lower and upper grade, which are deened in terms of the size of balls contained in the set of best approximants from J. These quantities serve to measure how far J resembles an M-summand, and they enter into geometric descriptions in various ways. For instance they allow estimates of the interior of the metric complement of J and of lower bounds for Lipschitz projections onto M-ideals.
منابع مشابه
AN EXTENDED NOTION OF THE GRADE OF AN IDEAL, AND GORENSTEIN RINGS
In this paper we shall apply modules of generalized fractions to extend the notion of the grade of an ideal, and to obtain characterizations of Gorenstein rings.
متن کاملOn natural homomorphisms of local cohomology modules
Let $M$ be a non-zero finitely generated module over a commutative Noetherian local ring $(R,mathfrak{m})$ with $dim_R(M)=t$. Let $I$ be an ideal of $R$ with $grade(I,M)=c$. In this article we will investigate several natural homomorphisms of local cohomology modules. The main purpose of this article is to investigate when the natural homomorphisms $gamma: Tor^{R}_c(k,H^c_I(M))to kotim...
متن کاملPrioritizing the indexes of Discretion, Heterogeny and Autogeny factors in order to analyze and evaluate their readiness for ideal situation of Central bank of the Islamic republic of Iran
the purpose of this research is to prioritize the indexes of discretion, Heterogeny and Autogeny factors in order to analyze and evaluate their readiness for ideal situation of Central bank of the Islamic Republic of Iran (CBI). This research is an exploratory kind and in terms of method is a survey kind. The data collection tool is questionnaire. After two Delphi cycles, in final questionnaire...
متن کاملTHE INTERNAL IDEAL LATTICE IN THE TOPOS OF M-SETS
We believe that the study of the notions of universal algebra modelled in an arbitarry topos rather than in the category of sets provides a deeper understanding of the real features of the algebraic notions. [2], [3], [4], [S], [6], [7], [13], [14] are some examples of this approach. The lattice Id(L) of ideals of a lattice L (in the category of sets) is an important ingredient of the categ...
متن کاملThe Fuzziness of Fuzzy Ideals
The backing of the fuzzy ideal is normal ideal in some ring and in same time there fuzzy set whose is not fuzzy ideal and it backing set is ideal, i.e., it crisp is normal ideal. Consequently, in this paper we constructing a fuzziness function which defined on fuzzy sets and assigns membership grade for every fuzzy set whose it backing set are crisp ideal. Now, Let be collection of all fuzzy s...
متن کاملBiprojectivty of Banach algebras modulo an ideal
In this paper, we introduce the new concept of biprojectivity of a Banach algebra modulo an ideal, as a generalization of this notion in the classical case. By using it , we obtain some necessary and sufficient conditions for contractibility of Banach algebras modulo an ideal. In particular we characterize the contractibility of quotient Banach algebras. Also we study the relationship between t...
متن کامل