bluuebunny/crossref_metadata_2025_split huggingface dataset:
On 𝑅-Subweakly Commuting Maps and Invariant Approximations in Banach Spaces
Authors: Shahzad Naseer 
Published: February 2021

Abstarct
The paper discusses a new class of noncommuting maps called 𝑅-subweakly commuting maps. The existence of invariant approximations for this class of maps is established. Our results extend, generalize, and improve some known results existing in the literature.
Quadric Hypersurfaces Containing a Projectively Normal Curve
Authors: Ballico Edoardo , Keem Changho 
Published: February 2021

Abstract
Let 𝐶 ⊂ 𝐏𝑛 be a smooth projectively normal curve. Let 𝑍 be the scheme-theoretic base locus of 𝐻0(𝐏𝑛, 𝐼𝐶(2)) and 𝑍′ the connected component of 𝑍 containing 𝐶. Here we show that 𝑍′ = 𝐶 in certain cases (e.g., non-special line bundles with degree near to 2𝑝𝑎
(𝐶)–2 or certain special line bundles on general 𝑘-gonal curves).
Functional Differential Inequalities with Unbounded Delay
Authors: Kamont Zdzisław , Nadolski Adam 
Published: February 2021

Abstract
We prove that a function of several variables satisfying a functional differential inequality with unbounded delay can be estimated by a solution of a suitable initial problem for an ordinary functional differential equation. As a consequence of the comparison theorem we obtain a Perron-type uniqueness result and a result on continuous dependence of solutions on given functions for partial functional differential equations with unbounded delay. We consider classical solutions on the Haar pyramid.
Semi-Slant Submanifolds of a Locally Product Manifold
Authors: Li Hongxia , Liu Ximin 
Published: February 2021

Abstract
In the present paper, we define and study the slant, bi-slant and semi-slant submanifolds of a locally product manifold. We give some characterization theorems for slant submanifolds and semi-slant submanifolds. Moreover, we obtain integrability conditions for the distributions which are involved in the definition of semi-slant submanifolds. We also get some results about mixed totally geodesic submanifolds.
Arcwise Connected Continua and Whitney Maps
Authors: Lončar Ivan 
Published: February 2021

Abstract
Let 𝑋 be a non-metric continuum, and 𝐶(𝑋) be the hyperspace of subcontinua of 𝑋. It is known that there is no Whitney map on the hyperspace 2𝑋 for non-metric Hausdorff compact spaces 𝑋. On the other hand, there exist non-metric continua which admit and ones which do not admit a Whitney map for 𝐶(𝑋). In particular, a locally connected or a rimmetrizable continuum 𝑋 admits a Whitney map for 𝐶(𝑋) if and only if it is metrizable. In this paper we investigate the properties of continua 𝑋 which admit a Whitney map for 𝐶(𝑋) or for 𝐶2(𝑋).
On the Fourier Multipliers of the Space 𝐿𝑝
Authors: Moussai Madani 
Published: February 2021

Abstract
We prove that the function 𝑚(ξ) = ψ (ξ) 𝑒𝑖ϕ(ξ) is not the Fourier multiplier of the space 𝐿𝑝, where the real phase ϕ has the property ϕ″ ≥ 𝑐 > 0, the amplitude ψ vanishes near the origin, ψ (ξ) = 𝑂(|ξ|–2) as ξ → ∞, and ψ′ ∈ 𝐿1.
Some Remarks Concerning Jones Eigenfrequencies and Jones Modes
Authors: Natroshvili David , Sadunishvili Guram , Sigua Irine 
Published: February 2021

Abstract
Three-dimensional fluid-solid interaction problems with regard for thermal stresses are considered. An elastic structure is assumed to be a bounded homogeneous isotropic body occupying a domain , where the thermoelastic four dimensional field is defined, while in the unbounded exterior domain there is defined the scalar (acoustic pressure) field. These two fields satisfy the differential equations of steady state oscillations in the corresponding domains along with the transmission conditions of special type on the interface ∂Ω±. We show that uniqueness of solutions strongly depends on the geometry of the boundary ∂Ω±. In particular, we prove that for the corresponding homogeneous transmission problem for a ball there exist infinitely many exceptional values of the oscillation parameter (Jones eigenfrequencies). The corresponding eigenvectors (Jones modes) are written explicitly. On the other hand, we show that if the boundary surface ∂Ω± contains two flat, non-parallel sub-manifolds then there are no Jones eigenfrequencies for such domains.
Problems of Statics of Two-Component Elastic Mixtures
Authors: Giorgashvili Levan , Skhvitaridze Ketevan 
Published: February 2021

Abstract
A general representation of solutions by six harmonic functions is obtained for a system of homogeneous equations of statics of two-component mixtures. The problems are investigated when the normal components of partial displacement vectors and the tangent components of partial rotation vectors are given on the boundary. Uniqueness theorems are proved. Solutions are obtained in terms of absolutely and uniformly convergent series.
Nonexistence of Weak Solutions for the 𝑝-Degenerate Subelliptic Inequalities Constructed by Generalized Baouendi–Grushin Vector Fields
Authors: Niu Pengcheng , Dou Jingbo , Zhang Huiqing 
Published: February 2021

Abstract
The purpose of this work is to study the nonexistence of weak solutions for 𝑝-degenerate subelliptic inequalities formed by the generalized Baouendi–Grushin vector fields. Also, we give the 𝑝-volume and 𝑝-area of the ball induced by the these vector fields.
Generalized De Leeuw Theorem
Authors: Gupta Sanjiv Kumar 
Published: February 2021

Abstract
A new restriction for the multipliers of 𝐿𝑝(𝐑) to 𝐿𝑝(𝐓) has been introduced. Our results generalize the famous De Leeuw's theorem on the transference of Fourier multipliers between 𝐑 and 𝐓.
Existence Results for First and Second Order Nonconvex Sweeping Processes with Perturbations and with Delay: Fixed Point Approach
Authors: Bounkhel Messaoud 
Published: February 2021

Abstract
We are interested in existence results for nonconvex functional differential inclusions. First, we prove an existence result, in separable Hilbert spaces, for first order nonconvex sweeping processes with perturbation and with delay. Then, by using this result and a fixed point theorem we prove an existence result for second order nonconvex sweeping processes with perturbation and with delay of the form 𝑢˙ (𝑡) ∈ 𝐶(𝑢(𝑡)), 𝑢¨(𝑡) ∈ –𝑁𝑃(𝐶(𝑢(𝑡)); 𝑢˙(𝑡)) + 𝐹(𝑡, 𝑢˙𝑡) when 𝐶 is a nonconvex bounded Lipschitz set-valued mapping and 𝐹 is a set-valued mapping with convex compact values taking their values in finite dimensional spaces.
Weyl's Theorem for Algebraically (𝑝, 𝑘)-Quasihyponormal Operators
Authors: Mecheri Salah 
Published: February 2021

Abstract
Let 𝐴 be a bounded linear operator acting on a Hilbert space 𝐻. The 𝐵-Weyl spectrum of 𝐴 is the set σ
𝐵𝑤(𝐴) of all ⋋ ∈ ℂ such that 𝐴 – ⋋𝐼 is not a 𝐵-Fredholm operator of index 0. Let 𝐸(𝐴) be the set of all isolated eigenvalues of 𝐴. Recently, in [Berkani and Arroud, J. Aust. Math. Soc. 76: 291–302, 2004] the author showed that if 𝐴 is hyponormal, then 𝐴 satisfies the generalized Weyl's theorem σ
𝐵𝑤(𝐴) = σ(𝐴) \ 𝐸(𝐴), and the 𝐵-Weyl spectrum σ
𝐵𝑤(𝐴) of 𝐴 satisfies the spectral mapping theorem. Lee [Han, Proc. Amer. Math. Soc. 128: 2291–2296, 2000] showed that Weyl's theorem holds for algebraically hyponormal operators. In this paper the above results are generalized to an algebraically (𝑝, 𝑘)-quasihyponormal operator which includes an algebraically hyponormal operator.
Approximating Common Fixed Points of Nonexpansive Mappings in Banach Spaces
Authors: Shahzad Naseer , Al-Dubiban Reem 
Published: February 2021

Abstract
Let 𝐾 be a nonempty closed convex subset of a real uniformly convex Banach space 𝐸 and 𝑆, 𝑇 : 𝐾 → 𝐾 two nonexpansive mappings such that 𝐹(𝑆) ∩ 𝐹(𝑇) := {𝑥 ∈ 𝐾 : 𝑆𝑥 = 𝑇𝑥 = 𝑥} ≠ ø. Suppose {𝑥𝑛} is generated iteratively by
𝑥1 ∈ 𝐾, 𝑥𝑛+1 = (1 – α
𝑛)𝑥𝑛 + α
𝑛𝑆[(1 – β
𝑛)𝑥𝑛 + β
𝑛𝑇𝑥𝑛],
𝑛 ≥ 1, where {α
𝑛}, {β
𝑛} are real sequences in [0, 1]. In this paper, we discuss the weak and strong convergence of {𝑥𝑛} to some 𝑥* ∈ 𝐹(𝑆) ∩ 𝐹(𝑇).
An Initial-Boundary Value Problem for a Viscous Compressible Flow
Authors: Hebeker Friedrich-Karl , Hsiao George C. 
Published: February 2021

Abstract
A constructive approach is presented to treat an initial boundary value problem for isothermal Navier–Stokes equations. It is based on a characteristics (Lagrangean) approximation locally in time and a boundary integral equation method via nonstationary potentials. As a basic problem, the latter leads to a Volterra integral equation of first kind which is proved to be uniquely solvable and even coercive in some anisotropic Sobolev spaces. The solution depends continuously upon the data and can be constructed by a quasioptimal Galerkin procedure.
Oscillation Criteria for Fourth Order Nonlinear Difference Equations
Authors: Agarwal Ravi P. , Grace Said R. , Akin-Bohner Elvan 
Published: February 2021

Abstract
Some new criteria for the oscillation of the fourth order difference equation
Δ2 (𝑎(𝑛)(Δ2𝑥(𝑛))
α
) + 𝑞(𝑛)𝑓(𝑥(𝑛 + 1)) = 0,
where α is the ratio of two positive odd integers are established.
On Existence of Nonoscillatory Solutions to Quasilinear Differential Equations
Authors: Astashova Irina V. 
Published: February 2021

Abstract
Sufficient conditions are established for the existence of nonoscillatory solutions to a quasilinear ordinary differential equation of higher order. For the equation with a positive potential, a criterion is established for the existence of nonoscillatory solutions with nonzero limit at infinity. In the case of even order, a criterion is obtained for all solutions at infinity to be oscillatory.
On a Periodic Boundary Value Problem for Fourth Order Linear Functional Differential Equations
Authors: Mukhigulashvili Sulkhan 
Published: February 2021

Abstract
The unimprovable sufficient conditions are established for the unique solvability of the periodic problem

where ℓ𝑖 : 𝐶([0, 𝑤]) → 𝐿([0, 𝑤]) are linear bounded operators, 𝑞 ∈ 𝐿([0, 𝑤]) and 𝑐𝑗 ∈ 𝑅
On the Stability in Bonnet's Theorem of the Surface Theory
Authors: Reshetnyak Yuri G. 
Published: February 2021

Abstract
In the space , 𝑛-dimensional surfaces are considered having the parametrizations which are functions of the Sobolev class with 𝑝 > 𝑛. The first and the second fundamental tensor are defined. The Peterson–Codazzi equations for such functions are understood in some generalized sense. It is proved that if the first and the second fundamental tensor of one surface are close to the first and, respectively, to the second fundamental tensor of the other surface, then these surfaces will be close up to the motion of the space . A difference between the fundamental tensors and the nearness of the surfaces are measured with the help of suitable 𝑊-norms. The proofs are based on a generalization of Frobenius' theorem about completely integrable systems of the differential equations which was proved by Yu. E. Borovskiĭ. The integral representations of functions by differential operators with complete integrability condition are used, which were elaborated by the author in his other works.
On Some Properties of Solutions of Polyharmonic Equation in Polyhedral Angles
Authors: Tavkhelidze Ilia 
Published: February 2021

Abstract
For a higher order differential equation with the polyharmonic operator, the Dirichlet and Riquier boundary value problems are studied in some polyhedral angles. Uniqueness theorems for solutions with a bounded “energy integral” of the corresponding BVPs are proved. Recurrent formulas are constructed for representation of fundamental solutions and Green's functions. The asymptotic behavior of solutions at infinity is studied.
On Lower and Semi-Lower Density Operators
Authors: Hejduk Jacek , Loranty Anna 
Published: February 2021

Abstract
This paper contains some results connected with topologies generated by lower and semi-lower density operators. We show that in some measurable spaces (𝑋, 𝑆, 𝐽) there exists a semi-lower density operator which does not generate a topology. We investigate some properties of nowhere dense sets, meager sets and σ-algebras of sets having the Baire property, associated with the topology generated by a semi-lower density operator.
Oscillation Theorems for Differential Equations Involving Even Order Nonlinear Sturm–Liouville Operator
Authors: Tanigawa Tomoyuki 
Published: February 2021

Abstract
We are concerned with the oscillatory and nonoscillatory behavior of solutions of differential equations involving an even order nonlinear Sturm–Liouville operator of the form

where α and β are distinct positive constants. We first give the criteria for the existence of nonoscillatory solutions with specific asymptotic behavior on infinite intervals, and then derive necessary and sufficient conditions for all solutions of (∗) to be oscillatory by eliminating all nonoscillatory solutions of (∗).
On the Uniqueness of Meromorphic Functions That Share Two Sets
Authors: Banerjee Abhijit 
Published: February 2021

Abstract
Using the notion of weighted and truncated sharings of sets we deal with the problem of uniqueness of meromorphic functions sharing two sets and obtain five theorems which not only improve a recent result of Yi and Lü [Acta Math. Sci. Ser. B Engl. Ed. 24: 83–90, 2004], but also improve and supplement the results of Lin and Yi [Kyungpook Math. J. 43: 73–85, 2003], Yi [Acta Math. Sinica (Chin. Ser.) 45: 75–82, 2002].
Compact Commutators on Morrey Spaces with Non-Doubling Measures
Authors: Sawano Yoshihiro , Shirai Satoru 
Published: February 2021

Abstract
We study multi-commutators on the Morrey spaces generated by BMO functions and singular integral operators or by BMO functions and fractional integral operators. We place ourselves in the setting of coming with a Radon measure μ which satisfies a certain growth condition. The Morrey-boundedness of commutators is established by M. Yan and D. Yang. However, the corresponding assertion of Morrey-compactness is still missing. The aim of this paper is to prove that the multi-commutators are compact if one of the BMO functions can be approximated with compactly supported smooth functions.
The Existence of Solutions for Nonlinear Operator Equations
Authors: Galewski Marek 
Published: February 2021

Abstract
We provide the existence results for a nonlinear operator equation
Λ*Φ′ (Λ𝑥) = 𝐹′(𝑥),
in case 𝐹 – Φ is not necessarily convex. We introduce the dual variational method which is based on finding global minima of primal and dual action functionals on certain nonlinear subsets of their domains and on investigating relations between the minima obtained. The solution is a limit of a minimizng sequence whose existence and convergence are proved. The application for the non-convex Dirichlet problem with P.D.E. is given.
Coincidence and Fixed Points of Contractive Type Multivalued Maps
Authors: Kamran Tayyab 
Published: February 2021

Abstract
Some fixed and coincidence point theorems are obtained in the setting of single and multivalued mappings, whose images are not necessarily bounded. Our results generalize some recent results by Daffer and Kaneko [Sci. Math. 1: 125–131, 1998] and others.
Integral Representations and Continuous Projectors in Some Spaces of Analytic and Pluriharmonic Functions
Authors: Oniani Gigla , Tsibadze Lamara 
Published: February 2021

Abstract
We consider analytic and pluriharmonic functions belonging to the classes 𝐵𝑝(Ω) and 𝑏𝑝(Ω) and defined in the ball . The theorems established in the paper make it possible to obtain some integral representations of functions of the above-mentioned classes. The existence of bounded projectors from the space 𝐿(ρ, Ω) into the space 𝐵𝑝(Ω) and from the space 𝐿(ρ, Ω) into the space 𝑏𝑝(Ω) is proved. Also, consideration is given to the existence of boundary values of fractional integrals of functions of the spaces 𝐵𝑝(Ω) and 𝑏𝑝(Ω).
Completions of Non-Symmetric Metric Spaces Via Enriched Categories
Authors: Schmitt Vincent 
Published: February 2021

Abstract
It is known from [Lawvere, Repr. Theory Appl. Categ. 1: 1–37 2002] that nonsymmetric metric spaces correspond to enrichments over the monoidal closed category [0, ∞]. We use enriched category theory and in particular a generic notion of flatness to describe various completions for these spaces. We characterise the weights of colimits commuting in the base category [0, ∞] with the conical terminal object and cotensors. Those can be interpreted in metric terms as very general filters, which we call filters of type 1. This correspondence extends the one between minimal Cauchy filters and weights which are adjoint as modules. Translating elements of enriched category theory into the metric context, one obtains a notion of convergence for filters of type 1 with a related completeness notion for spaces, for which there exists a universal completion. Another smaller class of flat presheaves is also considered both in the context of both metric spaces and preorders. (The latter being enrichments over the monoidal closed category 2.) The corresponding completion for preorders is the so-called dcpo completion.
Some Equivariant Constructions in Noncommutative Algebraic Geometry
Authors: Škoda Zoran 
Published: February 2021

Abstract
We here present rudiments of an approach to geometric actions in noncommutative algebraic geometry, based on geometrically admissible actions of monoidal categories. This generalizes the usual (co)module algebras over Hopf algebras which provide affine examples. We introduce a compatibility of monoidal actions and localizations which is a distributive law. There are satisfactory notions of equivariant objects, noncommutative fiber bundles and quotients in this setup.
Isomorphism Characterization of Divisible Groups in Modular Abelian Group Rings
Authors: Danchev Peter 
Published: February 2021

Abstract
Suppose G is an abelian group with a p-subgroup H and R is a commutative unitary ring of prime characteristic p with trivial nil-radical. We give a complete description up to isomorphism of the maximal divisible subgroups of 1 + I(RG;H) and (1 + I(RG;H))=H, respectively, where I(RG;H) denotes the relative augmentation ideal of the group algebra RG with respect to H.
This paper terminates a series of works by the author on the topic, first of which are [Danchev, Rad. Mat. 13: 23–32, 2004] and [Danchev, Bull. Georgian Acad. Sci. 174: 238–242, 2006].
A Note on the Boundedness of the Hilbert Transform in Weighted Grand Lebesgue Spaces
Authors: Kokilashvili Vakhtang , Meskhi Alexander 
Published: February 2021

Abstract
It is proved that the Hilbert transform defined on a finite interval is bounded in the grand Lebesgue space if and only if 𝑤 satisfies the Muckenhoupt condition 𝐴𝑝.
On the Necessary and Sufficient Conditions for the Stability of Linear Generalized Ordinary Differential, Linear Impulsive and Linear Difference Systems
Authors: Akhalaia Shota , Ashordia Malkhaz , Kekelia Nestan 
Published: February 2021

Abstract
Necessary and sufficient conditions are established for the stability in the Lyapunov sense of solutions of a linear system of generalized ordinary differential equations
𝑑𝑥(𝑡) = 𝑑𝐴(𝑡) · 𝑥(𝑡) + 𝑑𝑓(𝑡),
where and are, respectively, matrix- and vector-functions with bounded total variation components on every closed interval from . The results are realized for the linear systems of impulsive, ordinary differential and difference equations.
The Jawerth–Franke Embedding of Spaces with Dominating Mixed Smoothness
Authors: Hansen Markus , Vybíral Jan 
Published: February 2021

Abstract
We give a proof of the Jawerth embedding for function spaces with dominating mixed smoothness of Besov and Triebel–Lizorkin type

where
0 < 𝑝0 < 𝑝1 ≤ ∞ and 0 < 𝑞0,𝑞1 ≤ ∞
and

with

If 𝑝1 < ∞, we prove also the Franke embedding

Our main tools are discretization by a wavelet isomorphism and multivariate rearrangements.
Approximation by Bézier variant of the Szász–Kantorovich operators in case α < 1
Authors: Gupta Vijay , Zeng Xiao-Ming 
Published: February 2021

Abstract
The present paper deals with the Bézier variant of the Szász–Kantorovich operator. Its approximation properties are studied. A convergence theorem of this type approximation operators for locally bounded functions is established, which subsumes the approximation of functions of bounded variation as a special case.
Approximation by Nörlund means of Walsh–Kaczmarz–Fourier series
Authors: Nagy Károly 
Published: February 2021

Abstract
In this paper we study the rate of the approximation by Nörlund means of Walsh–Kaczmarz–Fourier series of a function in Lp
(1 ≤ p ≤ ∞). As a special case, we obtain the result due to Skvortsov [Anal. Math. 7: 141–150, 1981]. Earlier results on the Walsh–Nörlund means were given by Móricz and Siddiqi [J. Approx. Theory 70: 375–389, 1992].
Fixed point theorems for singlevalued and multivalued generalized contractions in metric spaces endowed with a graph
Authors: Nicolae Adriana , O'Regan Donal , Petruşel Adrian 
Published: February 2021

Abstract
The purpose of this paper is to present some fixed point results for self-generalized (singlevalued and multivalued) contractions in ordered metric spaces and in metric spaces endowed with a graph. Our theorems generalize and extend some recent results in the literature.
BIOCHEMICAL AND HISTOLOGICAL CHANGES ASSOCIATED WITH DOWNY MILDEW (Plasmopara halstedii (Farl.) Berl. and de Toni) INFECTION IN SUNFLOWER (Helianthus annuus L.) / MODIFICACIONES BIOQUIMICAS E HISTOLOGICAS RELACIONADAS CON LA INFECCION DEL GIRASOL (Helianthus annuus L.) POR EL AGENTE DE MILDIU (Plasmopara halstedii (Farl.) Berl. y de Toni) / CHANGEMENTS BIOCHIMIQUES ET HISTOLOGIQUES ASSOCIÉS À L’INFECTION DU TOURNESOL (Helianthus annuus L.) PAR LE MILDIOU (Plasmopara halstedii (Farl.) Berl. et de Toni)
Authors: Kumar B.R. Prashanth , Kulkarni Mahesh J. , Rao B.N. Veena , Chandrika K. , Gowda V.R. Balakrishna , Prasad D. Theertha 
Published: February 2021

SUMMARY
Biochemical changes associated with downy mildew infection in sunflower revealed an increase in the total soluble proteins, 0-40% ammonium sulfate fractionated proteins and total soluble sugars. Molecular sieve chromatography of 0-40% ammonium sulphate fraction revealed for presence of a high molecular weight protein and polysaccharide in the downy mildew infected sunflower leaves. Antibodies raised against the high molecular weight protein and polysaccharide were used in the western blot/dot blot analysis. It has been shown that the downy mildew disease also induces PR proteins, which have antigenic homology with PR-S protein, a member of the PR-5 class of proteins. An increase in iPA (isopentenyl adenosine) content in the infected sample was observed. A positive correlation exists between iPA level, 0-40% protein and total sugar content. Histological studies revealed that the downy mildew fungal mycelium extensively proliferates, ramifies extensively the leaf tissue and forms a nutritional link with the host cell by producing the intracellular haustorium.
TEMPERATURE - GERMINATION RESPONSES OF SUNFLOWER (Helianthus annuus L.) GENOTYPES / GERMINACION COMO REACCION A LA TEMPERATURA EN LOS GENOTIPOS DEL GIRASOL (Helianthus annuus L.) / GERMINATION - RÉACTION À LA TEMPÉRATURE DANS LES GÉNOTYPES DE TOURNESOL (Helianthus annuus L.)
Authors: Khalifa F.M. , Schneiter A.A. , El Tayeb E.I. 
Published: February 2021

SUMMARY
Seed germination of six sunflower (Helianthus annuus L.) hybrids was investigated across a range of eleven constant temperatures between 5°C and 45°C. Large temperature differences in germination rate 1/t (d-1), cardinal temperature (°C) and thermal time θ (°cd) were observed among hybrids. Base temperatures (Tb) varied between 3.3°C and 6.7°C whereas maximum germination temperatures (Tm) varied between 41.7°C and 48.9°C. Final germination fraction was attained at 15°C - 25°C whereas the maximum rate of germination was attained at 30.4°C - 35.6°C. The maximum germination rate of hybrid USDA 894, the cultivar with the slowest germination rate, was only 50% of that of hybrid EX 47. The low Tb and high Tm of sunflower appear to be one of the factors which explain the successful adaptation of sunflower to a wide range of temperature. These findings are discussed in relation to the origin of the crop and its wide adaptations in diverse habitats and climatic zones.