On ideal convergence of double sequences in probabilistic normed spaces

The notion of ideal convergence is a generalization of statistical convergence which has been intensively investigated in last few years.For an admissible ideal ∮N× N,the aim of the present paper is to introduce the concepts of ∮-convergence and ∮*-convergence for double sequences on probabilistic normed spaces(PN spaces for short).We give some relations related to these notions and find condition on the ideal ∮ for which both the notions coincide.We also define ∮-Cauchy and ∮*-Cauchy double sequences on PN spaces and show that ∮-convergent double sequences are ∮-Cauchy on these spaces.We establish example which shows that our method of convergence for double sequences on PN spaces is more general.     

非线性映射具误差的迭代序列在Banach空间中的收敛问题

In this paper,the approximation problems of Ishikawa iteration with errors of fixedpoints for asymptotically nonexpansive mappings and asymptotically pseudocontractivemappings in arbitrary real Banach spaces are investigated. Some necessary condition andsufficient condition for the convergence of iterative sequences are given respectively. The resultsthus extend and improve some recent corresponding results.     

Spectrum of operators in ideal spaces

One considers “weighted translation” operators in ideal Banach spaces. It is proved that if the translation is aperiodic (the set of periodic points has measure zero), then the spectrum of such an operator is rotationinvariant. This result can be extended (under certain additional restrictions) to “weighted translation” operators acting in regular subspaces of ideal spaces, in particular, to operators in Hardy spaces. In this note we prove the rotation-invariance of the spectrum of aperiodic operators of “weighted translation” in ideal spaces and uniform B-algebras. Translated from Zapiski Nauchnykh Seminarov Leningradskogo Otdeleniya Matematicheskogo Instituta im. V. A. Steklova AN SSSR, Vol. 65, pp. 196–198, 1976.     

Subsets of ideal topological spaces

Properties of α-I-open sets, t-I-sets, strong β-I-open sets, S _βI-sets and S-I-sets in ideal topological spaces are discussed. Also, we define a new class of sets called semi-I-locally closed sets which contains the class of all I-locally closed sets and is contained in the class of all semilocally closed sets.     

Biharmonic ideal hypersurfaces in Euclidean spaces

Let $x:M\to {\mathbb{E}}^m$ be an isometric immersion from a Riemannian n-manifold into a Euclidean m-space. Denote by Δ and $\overrightarrow{x}$ the Laplace operator and the position vector of M, respectively. Then M is called biharmonic if ${\mathrm{\Delta }}^2\overrightarrow{x}=0$. The following Chen?s Biharmonic Conjecture made in 1991 is well-known and stays open: The only biharmonic submanifolds of Euclidean spaces are the minimal ones. In this paper we prove that the biharmonic conjecture is true for $\delta (2)$-ideal and $\delta (3)$-ideal hypersurfaces of a Euclidean space of arbitrary dimension.     

The Jensen inequality in ideal spaces

The Jensen inequality is established for a lower semicontinuous convex functional defined on an ideal Banach space with order continuous norm.     

On the Corona problem

We show that if f₁, f₂ are bounded holomorphic functions in the unit ball of ℂⁿ such that , |f₁(z)|² + |f₂(z)2|² ≥ δ² >; 0, then any functionh in the Hardy space ,p < +∞ can be decomposed ash = f₁h₁ + f₂h₂ with . The Corona theorem in would be the same result withp = +∞ and this question is still open forn ≳-2, but the preceding result goes in this direction.     

On ideal convergence in probabilistic normed spaces

An interesting generalization of statistical convergence is I-convergence which was introduced by P.Kostyrko et al [KOSTYRKO,P.—ŠALáT,T.—WILCZYŃSKI,W.: I-Convergence, Real Anal. Exchange 26 (2000–2001), 669–686]. In this paper, we define and study the concept of I-convergence, I*-convergence, I-limit points and I-cluster points in probabilistic normed space. We discuss the relationship between I-convergence and I*-convergence, i.e. we show that I*-convergence implies the I-convergence in probabilistic normed space. Furthermore, we have also demonstrated through an example that, in general, I-convergence does not imply I*-convergence in probabilistic normed space.     

Strong ideal convergence in probabilistic metric spaces

In the present paper we introduce the concepts of strongly ideal convergent sequence and strong ideal Cauchy sequence in a probabilistic metric (PM) space endowed with the strong topology, and establish some basic facts. Next, we define the strong ideal limit points and the strong ideal cluster points of a sequence in this space and investigate some properties of these concepts.     

Nadel-type multiplier ideal sheaves on complex spaces with singularities

In this article, we introduce multiplier ideal sheaves on complex spaces with singularities(not necessarily normal) via Ohsawa’s extension measure, as a special case of which, it turns out to be the socalled Mather-Jacobian multiplier ideals in the algebro-geometric setting. Inspired by Nadel’s coherence and Guan-Zhou’s strong openness properties of the multiplier ideal sheaves, we discuss similar properties for the generalized multiplier ideal sheaves. As applications, we obtain a reasonable ge...     

Two-tuple balance of non-binary sequences with ideal two-level autocorrelation

Let p be a prime, q=p^m and F_q be the finite field with q elements. In this paper, we will consider q-ary sequences of period qⁿ-1 for q>2 and study their various balance properties: symbol-balance, difference-balance, and two-tuple-balance properties. The array structure of the sequences is introduced, and various implications between these balance properties and the array structure are proved. Specifically, we prove that if a q-ary sequence of period qⁿ-1 is difference-balanced and has the “cyclic” array structure then it is two-tuple-balanced. We conjecture that a difference-balanced q-ary sequence of period qⁿ-1 must have the cyclic array structure. The conjecture is confirmed with respect to all of the known q-ary sequences which are difference-balanced, in particular, which have the ideal two-level autocorrelation function when q=p.     

A decomposition of continuity in ideal topological spaces

We introduce the notions of w-I-continuous and w*-I-continuous functions in ideal topological spaces and investigate some of their properties. Additionally, we obtain a decomposition of continuous functions.     

Generalized closed sets with respect to an ideal in bitopological spaces

An ideal on a set X is a nonempty collection of subsets of X with heredity property which is also closed under finite unions. The concept of generalized closed sets in bitopological spaces was introduced by Sundaram. In this paper, we introduce and study the concept of generalized closed sets with respect to an ideal in an ideal bitopological space.     

⋆-Extremally disconnected ideal topological spaces

The notion of ?-extremally disconnected ideal topological spaces is introduced and studied. Many characterizations of the space are obtained.     

The Fitting ideal problem

Let A be a Noetherian local ring and let E be a finitely generatedA-module having rank r. In this note one deals with the expectedinequality (^rE) height (Fitt_r(E)), where height (Fitt_r(E))is the codimension of the rth Fitting ideal of E, and (M) standsfor the analytic spread of a module M. One establishes caseswhere the inequality holds as well as where it fails. A specialcase where the inequality holds implies the celebrated Zak inequalityfor the dimension of the image of the Gauss map.