Tusi Mathematical Research Group (TMRG) and Department of Pure Mathematics, Ferdowsi University of Mashhad (in cooperation with
The Center of Excellence in Analysis on Algebraic Structures)
Khayyam Journal of Mathematics
2423-4788
3
1
2017
01
01
Stability Results for Neutral Integro-Differential Equations with Multiple Functional Delays
1
11
EN
Ernest
Yankson
Department of Mathematics and Statistics, University of Cape Coast, Cape
Coast, Ghana.
ernestoyank@gmail.com
10.22034/kjm.2017.43831
Necessary and sufficient conditions for the zero solution of the nonlinear neutral integro-differential equationbegin{eqnarray*}&&frac{d}{dt}Big(r(t)Big[x(t)+Q(t, x(t-g_1(t)),...,x(t-g_N(t)))Big]Big)\ &&= -a(t)x(t)+ sum^{N}_{i=1}int^{t}_{t-g_i(t)}k_i(t,s)f_i(x(s))ds end{eqnarray*} to be asymptotically stable are obtained. In the process we invert the integro-differential equation and obtain an equivalent integral equation. The contraction mapping principle is used as the main mathematical tool for establishing the necessary and sufficient conditions.
Stability,integro-differential equation,functional delay
http://www.kjm-math.org/article_43831.html
http://www.kjm-math.org/article_43831_2161050be631ca19a702fe6a0bd6d1c3.pdf
Tusi Mathematical Research Group (TMRG) and Department of Pure Mathematics, Ferdowsi University of Mashhad (in cooperation with
The Center of Excellence in Analysis on Algebraic Structures)
Khayyam Journal of Mathematics
2423-4788
3
1
2017
01
01
Periodic Solutions for Third-Order Nonlinear Delay Differential Equations with Variable Coefficients
12
21
EN
Abdelouaheb
Ardjouni
Department of Mathematics and Informatics, University of Souk Ahras, P.O.
Box 1553, Souk Ahras, 41000, Algeria.
abd_ardjouni@yahoo.fr
Farid
Nouioua
Department of Mathematics and Informatics, University of Souk Ahras, P.O.
Box 1553, Souk Ahras, 41000, Algeria.
fnouioua@gmail.com
Ahcene
Djoudi
Department of Mathematics, University of Annaba, P.O. Box 12, Annaba,
23000, Algeria.
adjoudi@yahoo.com
10.22034/kjm.2017.44493
In this paper, the following third-order nonlinear delay differential equationwith periodic coefficients%begin{align*}& x^{primeprimeprime}(t)+p(t)x^{primeprime}(t)+q(t)x^{prime}(t)+r(t)x(t)\& =fleft( t,xleft( tright) ,x(t-tau(t))right) +frac{d}{dt}gleft(t,xleft( t-tauleft( tright) right) right) ,end{align*}is considered. By employing Green's function, Krasnoselskii's fixed pointtheorem and the contraction mapping principle, we state and prove theexistence and uniqueness of periodic solutions to the third-order nonlineardelay differential equation.
fixed point,periodic solutions,third-order nonlinear delay differential equations
http://www.kjm-math.org/article_44493.html
http://www.kjm-math.org/article_44493_fca28ec0388a064bcfebffd47c16b12f.pdf
Tusi Mathematical Research Group (TMRG) and Department of Pure Mathematics, Ferdowsi University of Mashhad (in cooperation with
The Center of Excellence in Analysis on Algebraic Structures)
Khayyam Journal of Mathematics
2423-4788
3
1
2017
01
01
Operators Reversing Orthogonality and Characterization of Inner Product Spaces
22
24
EN
Paweł
Wójcik
Institute of Mathematics, Pedagogical University of Cracow, Podchorążych
2, 30-084 Kraków, Poland.
pwojcik@up.krakow.pl
10.22034/kjm.2017.44746
In this short paper we answer a question posed by Chmieliński in [Adv. Oper. Theory, 1 (2016), no. 1, 8-14]. Namely, we prove that among normed spaces of dimension greater than two,only inner product spaces admit nonzero linear operators which reverse the Birkhoff orthogonality.
Birkhoff orthogonality,orthogonality reversing mappings,characterizations of inner product spaces
http://www.kjm-math.org/article_44746.html
http://www.kjm-math.org/article_44746_9f829bbb7fc2df9483fd2622f9084732.pdf
Tusi Mathematical Research Group (TMRG) and Department of Pure Mathematics, Ferdowsi University of Mashhad (in cooperation with
The Center of Excellence in Analysis on Algebraic Structures)
Khayyam Journal of Mathematics
2423-4788
3
1
2017
01
01
Certain Properties of a Subclass of Univalent Functions With Finitely Many Fixed Coefficients
25
32
EN
S.Sunil
Varma
Department of Mathematics, Madras Christian College, Tambaram,
Chennai-600059, Tamil Nadu, India
sunilvarma@mcc.edu.in
Thomas
Rosy
Department of Mathematics, Madras Christian College, Tambaram,
Chennai-600059, Tamil Nadu, India
thomas.rosy@gmail.com
10.22034/kjm.2017.44920
In this paper a new class of analytic, univalent and normalized functions with finitely many fixed coefficients is defined. Properties like coefficient condition, radii of starlikeness and convexity, extreme points and integral operators applied to functions in the class are investigated.
Analytic function,univalent function,fixed coefficient,Extreme point
http://www.kjm-math.org/article_44920.html
http://www.kjm-math.org/article_44920_245bef22255f8b0b38f19d4c0c83a25b.pdf
Tusi Mathematical Research Group (TMRG) and Department of Pure Mathematics, Ferdowsi University of Mashhad (in cooperation with
The Center of Excellence in Analysis on Algebraic Structures)
Khayyam Journal of Mathematics
2423-4788
3
1
2017
01
01
On Para-Sasakian Manifolds Satisfying Certain Curvature Conditions with Canonical Paracontact Connection
33
43
EN
Selcen
Yüksel Perktaş
Faculty of Arts and Science, Department of Mathematics, Adıyaman University, Adıyaman, Turkey
sperktas@adiyaman.edu.tr
10.22034/kjm.2017.45190
In this article, the aim is to introduce a para-Sasakian manifold with acanonical paracontact connection. It is shown that $varphi$-conharmonically flat, $varphi $-$W_{2}$ flat and $varphi $-pseudo projectively flat para-Sasakian manifolds with respect to canonical paracontact connection are all $eta $-Einsteinmanifolds. Also, we prove that quasi-pseudo projectively flatpara-Sasakian manifolds are of constant scalar curvatures.
Canonical connection,paracontact metric structure,normal structure
http://www.kjm-math.org/article_45190.html
http://www.kjm-math.org/article_45190_7d44a17d67db3000195bfd95cc73a650.pdf
Tusi Mathematical Research Group (TMRG) and Department of Pure Mathematics, Ferdowsi University of Mashhad (in cooperation with
The Center of Excellence in Analysis on Algebraic Structures)
Khayyam Journal of Mathematics
2423-4788
3
1
2017
01
01
Approximation for a Summation-Integral Type Link Operators
44
60
EN
Arun
Kajla
Department of Mathematics, Central University of Haryana, Haryana-123031,
India.
rachitkajla47@gmail.com
10.22034/kjm.2017.45322
The present article deals with the general family of summation-integral type operators. Here, we propose the Durrmeyer variant of the generalized Lupaş operators considered by Abel and Ivan (General Math. 15 (1) (2007) 21-34) and study local approximation, Voronovskaja type formula, global approximation, Lipchitz type space and weighted approximation results. Also, we discuss the rate of convergence for absolutely continuous functions having a derivative equivalent with a function of bounded variation.
Global approximation,rate of convergence,modulus of continuity,bounded variation
http://www.kjm-math.org/article_45322.html
http://www.kjm-math.org/article_45322_725917aec0e6b1c459fe81fc2e4d7411.pdf
Tusi Mathematical Research Group (TMRG) and Department of Pure Mathematics, Ferdowsi University of Mashhad (in cooperation with
The Center of Excellence in Analysis on Algebraic Structures)
Khayyam Journal of Mathematics
2423-4788
3
1
2017
01
01
Ostrowski's Inequality for Functions whose First Derivatives are $s$-Preinvex in the Second Sense
61
80
EN
Badreddine
Meftah
Laboratoire des t'el'ecommunications, Facult'e des
Sciences et de la Technologie, University of 8 May 1945 Guelma, P.O. Box
401, 24000 Guelma, Algeria.
badrimeftah@yahoo.fr
10.22034/kjm.2017.46863
In this paper, we establish some new Ostrowski type inequalities forfunctions whose first derivatives are $s$-preinvex in the second sense.
Ostrowski inequality,midpoint inequality,H"{o}lder inequality,power mean inequality,preinvex functions,$s$-preinvex functions
http://www.kjm-math.org/article_46863.html
http://www.kjm-math.org/article_46863_69c7dd0b531fa53298dd16c90cd3a0f8.pdf
Tusi Mathematical Research Group (TMRG) and Department of Pure Mathematics, Ferdowsi University of Mashhad (in cooperation with
The Center of Excellence in Analysis on Algebraic Structures)
Khayyam Journal of Mathematics
2423-4788
3
1
2017
01
01
Proximal Point Algorithms for Numerical Reckoning Fixed Points of Hybrid-Type Multivalued Mappings in Hilbert Spaces
81
89
EN
Kritsada
Lerkchaiyaphum
Department of Mathematics, Faculty of Science and Technology, Nakhon
Pathom Rajabhat University, Nakhon Pathom 73000, Thailand.
a_krit2@hotmail.com
Withun
Phuengrattana
Research Center for Pure and Applied Mathematics, Research and Development Institute, Nakhon Pathom Rajabhat University, Nakhon Pathom 73000,
Thailand.
withun_ph@yahoo.com
10.22034/kjm.2017.46951
In this paper, we propose a new iteration process to approximateminimizers of proper convex and lower semi-continuous functions andfixed points of $lambda$-hybrid multivalued mappings in Hilbertspaces. We also provide an example to illustrate the convergencebehavior of the proposed iteration process and numerically comparethe convergence of the proposed iteration scheme with the existingschemes.
Proximal point algorithm,hybrid multivalued mapping,Ishikawa iteration,S-iteration,Hilbert spaces
http://www.kjm-math.org/article_46951.html
http://www.kjm-math.org/article_46951_9c228d2ed70ca44facd3ac48e7b8797e.pdf