Some fixed point theorems in fuzzy reflexive Banach spaces

In this paper, we first show that there are some gaps in the fixed point theorems for fuzzy non-expansive mappings which are proved by Bag and Samanta, in [Bag T, Samanta SK. Fixed point theorems on fuzzy normed linear spaces. Inf Sci 2006;176:2910–31; Bag T, Samanta SK. Some fixed point theorems in fuzzy normed linear spaces. Inform Sci 2007;177(3):3271–89]. By introducing the notion of fuzzy and α- fuzzy reflexive Banach spaces, we obtain some results which help us to establish the correct version of fuzzy fixed point theorems. Second, by applying Theorem 3.3 of Sadeqi and Solati kia [Sadeqi I, Solati kia F. Fuzzy normed linear space and it’s topological structure. Chaos, Solitons & Fractals, in press] which says that any fuzzy normed linear space is also a topological vector space, we show that all topological version of fixed point theorems do hold in fuzzy normed linear spaces.     

Social choice theory without Pareto: The pivotal voter approach

This paper extends the pivotal voter approach pioneered by Barberá [Barberá, S., 1980. Pivotal voters: A new proof of Arrow’s Theorem. Economics Letters 6, 13–6; Barberá, S., 1983. Strategy-proofness and pivotal voters: A direct proof of the Gibbard-Satterthwaite Theorem. International Economic Review 24, 413–7] to all social welfare functions satisfying independence of irrelevant alternatives. Arrow’s Theorem, Wilson’s Theorem, and the Muller–Satterthwaite Theorem are all immediate corollaries of the main result. It is further shown that a vanishingly small fraction of pairs of alternatives can be affected in the group preference ordering by multiple individuals, which generalizes each of the above theorems.     

On the immersion of topological semigroups in topological groups

The Ore sufficient condition for imbedding of a semigroup in a group is extended to the case of topological semigroups. Imbedding conditions for a locally compact topological semigroup in a locally bicompact topological group are studied.Translated from Matematicheskie Zametki, Vol. 6, No. 4, October, 1969, pp. 401–409.     

Incorrect problems in topological spaces

Conclusions 15. According to the methods of § 3 and § 4, we are considering the solution on a bicompact set M, taking as approximate solutions the elements of this set, i.e., we restrict X to a bicompact space M.By virtue of the corollary of Theorem 5, this re-establishes the stability of the problem. Thus by using bicompact sets and the related additional information about the solution, it is possible to go over from an incorrect problem to a problem which is correct in the sense of Tikhonov (see [19], p. 4).Translated from Sibirskii Matematicheskii Zhurnal, Vol. 10, No. 5, pp. 1065–1074, September–October, 1969.     

Effective Solution of the Carleman Problem for Some Groups of Divergent Type

We consider a Fuchsian group of the first kind containing only hyperbolic transformations. We obtain an effective solution (explicit in terms of transformations of the group) to the Carleman boundary value problem on a fundamental polygon where the inverse shift is induced by the generating transformations of the group.Original Russian Text Copyright © 2005 Aksent’eva E. P. and Garif’yanov F. N.The authors were supported by the Russian Foundation for Basic Research (Grant 02-01-00914).__________Translated from Sibirskii Matematicheskii Zhurnal, Vol. 46, No. 4, pp. 723–733, July–August, 2005.     

Dyadic Diaphony of Digital Nets Over ?2

The dyadic diaphony, introduced by Hellekalek and Leeb, is a quantitative measure for the irregularity of distribution of point sets in the unit-cube. In this paper we study the dyadic diaphony of digital nets over ℤ₂. We prove an upper bound for the dyadic diaphony of nets and show that the convergence order is best possible. This follows from a relation between the dyadic diaphony and the L₂{\cal L}_2 discrepancy. In order to investigate the case where the number of points is small compared to the dimension we introduce the limiting dyadic diaphony, which is defined as the limiting case where the dimension tends to infinity. We obtain a tight upper and lower bound and we compare this result with the limiting dyadic diaphony of a random sample.     

Twist Functors and D-Branes

We discuss a categorical approach to the investigation of topological D-branes. Twist functors and their induced action on the cohomology ring of a manifold are studied. A nontrivial spherical object of the derived category of coherent sheaves of a reduced plane singular curve of degree 3 is constructed.__________Translated from Ukrains’kyi Matematychnyi Zhurnal, Vol. 57, No. 1, pp. 18–31, January, 2005.     

The construction of an iterative fractional scheme: the case of Joe

In his paper on A New Hypothesis Concerning Children’s Fractional Knowledge, Steffe (2002) demonstrated through the case study of Jason and Laura how children might construct their fractional knowledge through reorganization of their number sequences. He described the construction of a new kind of number sequence that we refer to as a connected number sequence (CNS). A CNS can result from the application of a child’s explicitly nested number sequence, ENS (Steffe, L. P. (1992). Learning and Individual Differences, 4(3), 259–309; Steffe, L. P. (1994). Children’s multiplying schemes. In: G. Harel, & J. Confrey (Eds.), (pp. 3–40); Steffe, L. P. (2002). Journal of Mathematical Behavior, 102, 1–41) in the context of continuous quantities. It requires the child to incorporate a notion of unit length into the abstract unit items of their ENS. Connected numbers were instantiated by the children within the context of making number-sticks using the computer tool TIMA: sticks. Steffe conjectured that children who had constructed a CNS might be able to use their multiplying schemes to construct composite unit fractions. (In the context of number-sticks a composite unit fraction could be a 3-stick as 1/8 of a 24-stick.) In the case of Jason and Laura, his conjecture was not confirmed. Steffe attributed the constraints that Jason and Laura experienced as possibly stemming from their lack of a splitting operation for composite units. In this paper we shall demonstrate, using the case study of Joe, how a child might construct the splitting operation for composite units, and how such a child was able to not only confirm Steffe’s conjecture concerning composite unit fractions, but also give support to our reorganization hypothesis by constructing an iterative fractional scheme (and consequently, a fractional connected number sequence (FCNS)) as a reorganization of his ENS.     

Remainders in compactifications and generalized metrizability properties

When does a Tychonoff space X have a Hausdorff compactification with the remainder belonging to a given class of spaces? A classical theorem of Henriksen and Isbell and certain theorems, involving a new completeness type property introduced below, are applied to obtain new results on remainders of topological spaces and groups. In particular, some strong necessary conditions for a topological group to have a metrizable remainder, or a paracompact p-remainder, are established (the group itself turns out to be a paracompact p-space (Theorem 4.8)). It follows that if a non-locally compact topological group G is metrizable at infinity, then G is a Lindelöf p-space, and the Souslin number of G is countable (Corollary 4.10). This solves Problem 10.28 from [M. Hušek, J. van Mill (Eds.), Recent Progress in General Topology, vol. 2, North-Holland, 2002, pp. 1–57].     

Homologies of distributive structures

In this paper we give a construction which makes it possible to determine the homologies of a bicompact topological space starting from the structure of its open sets.Translated from Matematicheskie Zametki, Vol. 12, No. 2, pp. 205–211, August, 1972.     

Motions in G-vector bundles (linear extensions) that are locally bounded and locally separated from zero

One considers a G-vector bundle over a minimal G-space, possessing the property that the motion of each of its points is bounded and separated from zero over a sufficiently small neighborhood of any point of the base. It is proved that this bundle has the structure of a fiber space with a bicompact structure group and, moreover, the action of the group G preserves the projection onto a fiber of the fiber space. With the aid of this result, a series of theorems regarding the representations of bicompact groups are carried over to G-vector bundles or, in another terminology, to linear extensions of topological groups of transformations.Translated from Teoriya Funktsii, Funktsional'nyi Analiz i Ikh Prilozheniya, No. 49, pp. 70–77, 1988.     

A short and constructive proof of Tarski’s fixed-point theorem

I give short and constructive proofs of Tarski’s fixed-point theorem, and of Zhou’s extension of Tarski’s fixed-point theorem to set-valued maps.I thank Charles Blair, William Thomson, an associated editor and a referee for their helpful suggestions.I have taught Tarski’s Theorem with F continuous to Caltech undergraduates.     

Distances on Lie groups of polynomial volume growth

For any simply connected solvable Lie group Q of polynomial volume growth, we introduce the notion of nil-shadow of Q. We shall give an explicit formula for the distance to the origin of an element q ∈ Q in terms of its exponential coordinates of the second kind taken in an appropriate basis. This result extends a previous result for nilpotent Lie groups [6, Theorem DN] and [7, Theorem 1].     

Adaptive Multiresolution Analysis on the Dyadic Topological Group

A type of multiresolution analysis on the space of continuous functions defined on the dyadic topological group is proposed, depending on free parameters. The appropriate choice of parameters is used to adapt this analysis to a given function.     

Elementarity and Dimensions

An alternative proof of Fedorchuk’s recent result that dim X ≤ Dg X for compact Hausdorff spaces X is given. The problem is reduced to the metric case by using the Lowenheim-Skolem theorem.__________Translated from Matematicheskie Zametki, vol. 78, no. 2, 2005, pp. 292–298.Original Russian Text Copyright © 2005 by K. P. Hart.     

Some results on generalized topological spaces and generalized systems

Summary We characterize some properties of generalized topological spaces and (g,g’)-continuity by using an interior operator defined on a generalized topological space. Also, we introduce the notions of (ψ, ψ’)-open map, gn-continuity, gn-open map and investigate their properties by using new interior (or closure) operators defined on generalized neighborhood systems of a nonempty set.     

Some Spectral Properties of One Sturm-Liouville Type Problem with Discontinuous Weight

We consider a discontinuous weight Sturm-Liouville equation together with eigenparameter dependent boundary conditions and two supplementary transmission conditions at the point of discontinuity. We extend and generalize some approaches and results of the classic regular Sturm-Liouville problems to the similar problems with discontinuities. In particular, we introduce a special Hilbert space formulation in such a way that the problem under consideration can be interpreted as an eigenvalue problem for a suitable selfadjoint operator, construct the Green’s function and resolvent operator, and derive asymptotic formulas for eigenvalues and normalized eigenfunctions.Original Russian Text Copyright © 2005 Mukhtarov O. Sh. and Kadakal M.__________Translated from Sibirskii Matematicheskii Zhurnal, Vol. 46, No. 4, pp. 860–875, July–August, 2005.     

Fractional Modified Dyadic Integral and Derivative on ℝ<Subscript>+</Subscript>

For functions in the Lebesgue space L(ℝ₊), a modified strong dyadic integral J _α and a modified strong dyadic derivative D ^(α) of fractional order α > 0 are introduced. For a given function f ∈ L(ℝ₊), criteria for the existence of these integrals and derivatives are obtained. A countable set of eigenfunctions for the operators J _α and D ^(α) is indicated. The formulas D ^(α)(J ^α(f)) = f and J _α(D ^(α)(f)) = f are proved for each α > 0 under the condition that . We prove that the linear operator is unbounded, where is the natural domain of J _α. A similar statement for the operator is proved. A modified dyadic derivative d ^(α)(f)(x) and a modified dyadic integral j _α(f)(x) are also defined for a function f ∈ L(ℝ₊) and a given point x ∈ ℝ₊. The formulas d ^(α)(J _α(f))(x) = f(x) and j _α(D ^(α)(f)) = f(x) are shown to be valid at each dyadic Lebesgue point x ∈ ℝ₊ of f.__________Translated from Funktsional’nyi Analiz i Ego Prilozheniya, Vol. 39, No. 2, pp. 64–70, 2005Original Russian Text Copyright © by B. I. GolubovSupported by the Russian Foundation for Basic Research (grant no. 05-01-00206).