eng
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
2423-4788
2017-01-01
3
1
1
11
10.22034/kjm.2017.43831
43831
Stability Results for Neutral Integro-Differential Equations with Multiple Functional Delays
Ernest Yankson
ernestoyank@gmail.com
1
Department of Mathematics and Statistics, University of Cape Coast, Cape Coast, Ghana.
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.
http://www.kjm-math.org/article_43831_2161050be631ca19a702fe6a0bd6d1c3.pdf
Stability
integro-differential equation
functional delay
eng
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
2423-4788
2017-01-01
3
1
12
21
10.22034/kjm.2017.44493
44493
Periodic Solutions for Third-Order Nonlinear Delay Differential Equations with Variable Coefficients
Abdelouaheb Ardjouni
abd_ardjouni@yahoo.fr
1
Farid Nouioua
fnouioua@gmail.com
2
Ahcene Djoudi
adjoudi@yahoo.com
3
Department of Mathematics and Informatics, University of Souk Ahras, P.O. Box 1553, Souk Ahras, 41000, Algeria.
Department of Mathematics and Informatics, University of Souk Ahras, P.O. Box 1553, Souk Ahras, 41000, Algeria.
Department of Mathematics, University of Annaba, P.O. Box 12, Annaba, 23000, Algeria.
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.
http://www.kjm-math.org/article_44493_fca28ec0388a064bcfebffd47c16b12f.pdf
fixed point
periodic solutions
third-order nonlinear delay differential equations
eng
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
2423-4788
2017-01-01
3
1
22
24
10.22034/kjm.2017.44746
44746
Operators Reversing Orthogonality and Characterization of Inner Product Spaces
Paweł Wójcik
pwojcik@up.krakow.pl
1
Institute of Mathematics, Pedagogical University of Cracow, Podchorążych 2, 30-084 Kraków, Poland.
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.
http://www.kjm-math.org/article_44746_9f829bbb7fc2df9483fd2622f9084732.pdf
Birkhoff orthogonality
orthogonality reversing mappings
characterizations of inner product spaces
eng
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
2423-4788
2017-01-01
3
1
25
32
10.22034/kjm.2017.44920
44920
Certain Properties of a Subclass of Univalent Functions With Finitely Many Fixed Coefficients
S.Sunil Varma
sunilvarma@mcc.edu.in
1
Thomas Rosy
thomas.rosy@gmail.com
2
Department of Mathematics, Madras Christian College, Tambaram, Chennai-600059, Tamil Nadu, India
Department of Mathematics, Madras Christian College, Tambaram, Chennai-600059, Tamil Nadu, India
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.
http://www.kjm-math.org/article_44920_245bef22255f8b0b38f19d4c0c83a25b.pdf
Analytic function
univalent function
fixed coefficient
Extreme point
eng
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
2423-4788
2017-01-01
3
1
33
43
10.22034/kjm.2017.45190
45190
On Para-Sasakian Manifolds Satisfying Certain Curvature Conditions with Canonical Paracontact Connection
Selcen Yüksel Perktaş
sperktas@adiyaman.edu.tr
1
Faculty of Arts and Science, Department of Mathematics, Adıyaman University, Adıyaman, Turkey
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.
http://www.kjm-math.org/article_45190_7d44a17d67db3000195bfd95cc73a650.pdf
Canonical connection
paracontact metric structure
normal structure
eng
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
2423-4788
2017-01-01
3
1
44
60
10.22034/kjm.2017.45322
45322
Approximation for a Summation-Integral Type Link Operators
Arun Kajla
rachitkajla47@gmail.com
1
Department of Mathematics, Central University of Haryana, Haryana-123031, India.
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.
http://www.kjm-math.org/article_45322_725917aec0e6b1c459fe81fc2e4d7411.pdf
Global approximation
rate of convergence
modulus of continuity
bounded variation
eng
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
2423-4788
2017-01-01
3
1
61
80
10.22034/kjm.2017.46863
46863
Ostrowski's Inequality for Functions whose First Derivatives are $s$-Preinvex in the Second Sense
Badreddine Meftah
badrimeftah@yahoo.fr
1
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.
In this paper, we establish some new Ostrowski type inequalities forfunctions whose first derivatives are $s$-preinvex in the second sense.
http://www.kjm-math.org/article_46863_69c7dd0b531fa53298dd16c90cd3a0f8.pdf
Ostrowski inequality
midpoint inequality
H"{o}lder inequality
power mean inequality
preinvex functions
$s$-preinvex functions
eng
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
2423-4788
2017-01-01
3
1
81
89
10.22034/kjm.2017.46951
46951
Proximal Point Algorithms for Numerical Reckoning Fixed Points of Hybrid-Type Multivalued Mappings in Hilbert Spaces
Kritsada Lerkchaiyaphum
a_krit2@hotmail.com
1
Withun Phuengrattana
withun_ph@yahoo.com
2
Department of Mathematics, Faculty of Science and Technology, Nakhon Pathom Rajabhat University, Nakhon Pathom 73000, Thailand.
Research Center for Pure and Applied Mathematics, Research and Development Institute, Nakhon Pathom Rajabhat University, Nakhon Pathom 73000, Thailand.
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.
http://www.kjm-math.org/article_46951_9c228d2ed70ca44facd3ac48e7b8797e.pdf
Proximal point algorithm
hybrid multivalued mapping
Ishikawa iteration
S-iteration
Hilbert spaces