

2018 . 

Bulletin of Iranian Mathematical Society
ISSN 1017060X
دوماهنامه  ( )
5 2016




 Forced oscillations of a damped Kortewegde Vries equation on a periodic domain M. Chen* Pages 10271038 Abstract Full Text [PDF 126KB]   In this paper، we investigate a damped Kortewegde Vries equation with forcing on a periodic domain T=R/(2πZ) . We can obtain that if the forcing is periodic with small amplitude، then the solution becomes eventually timeperiodic.
Keywords: Forced oscillation, Korteweg, de Vries equation, stability, time, periodic solution
  
 Boundary temperature reconstruction in an inverse heat conduction problem using boundary integral equation method M. Garshasbi * , F. Hassani Pages 10391057 Abstract Full Text [PDF 194KB]   In this paper، we consider an inverse boundary value problem for twodimensional heat equation in an annular domain. This problem consists of determining the temperature on the interior boundary curve from the Cauchy data (boundary temperature and heat flux) on the exterior boundary curve. To this end، the boundary integral equation method is used. Since the resulting system of linear algebraic equations is illposed، the Tikhonov firstorder regularization procedure is employed to obtain a stable solution. Determination of regularization parameter is based on Lcurve technique. Some numerical examples for the feasibility of the proposed method are presented.
Keywords: Inverse boundary problem, heat equation, boundary integral equation method, regularization
  
 On a generalization of condition (PWP) X. Liang * , Y. Luo Pages 10571076 Abstract Full Text [PDF 160KB]   There is a flatness property of acts over monoids called Condition (PWP) which، so far، has received much attention. In this paper، we introduce Condition GP(P)، which is a generalization of Condition (PWP). Firstly، some characterizations of monoids by Condition GP(P) of their (cyclic، Rees factor) acts are given، and many known results are generalized. Moreover، some possible conditions on monoids that describe when their diagonal acts satisfy Condition GP(P) are found. Finally، using some new types of epimorphisms، an alternative description of Condition GP(P) (resp.، Condition (PWP) is obtained، and directed colimits of these new epimorphisms are investigated.
Keywords: S, act, Condition (PWP), condition GP, (P), generally left right ideal, quasi G, 2, pure epimorphism
  
 Approximate solution of dual integral equations S. Ahdiaghdam* , K. Ivaz , S. Shahmorad Pages 10771086 Abstract Full Text [PDF 110KB]   We study dual integral equations which appear in formulation of the potential distribution of an electrified plate with mixed boundary conditions. These equations will be converted to a system of singular integral equations with Cauchy type kernels. Using Chebyshev polynomials، we propose a method to approximate the solution of Cauchy type singular integral equation which will be used to approximate the solution of the main dual integral equations. Numerical results demonstrate effectiveness of this method.
Keywords: Dual integral equation, Cauchy type integral equation, Fourier transform
  
 On the bounds in Poisson approximation for independent geometric distributed random variables T. L. Hung * , L. T. Giang Pages 10871096 Abstract Full Text [PDF 120KB]   The main purpose of this note is to establish some bounds in Poisson approximation for rowwise arrays of independent geometric distributed random variables using the operator method. Some results related to random sums of independent geometric distributed random variables are also investigated.
Keywords: Poisson approximation, linear operator, geometric random variable, random sums
  
 Numerical approach for solving a class of nonlinear fractional differential equation S. Irandoust , pakchin , M. Lakestani , H. Kheiri Pages 11071126 Abstract Full Text [PDF 203KB]   It is commonly accepted that fractional differential equations play an important role in the explanation of many physical phenomena. For this reason we need a reliable and efficient technique for the solution of fractional differential equations. This paper deals with the numerical solution of a class of fractional differential equation. The fractional derivatives are described based on the Caputo sense. Our main aim is to generalize the Chebyshev cardinal operational matrix to the fractional calculus. In this work، the Chebyshev cardinal functions together with the Chebyshev cardinal operational matrix of fractional derivatives are used for numerical solution of a class of fractional differential equations. The main advantage of this approach is that it reduces fractional problems to a system of algebraic equations. The method is applied to solve nonlinear fractional differential equations. Illustrative examples are included to demonstrate the validity and applicability of the presented technique.
Keywords: Fractional, order differential equation, operational matrix of fractional derivative, Caputo derivative, Chebyshev cardinal function, collocation method
  
 The use of inverse quadratic radial basis functions for the solution of an inverse heat problem F. Parzlivand , A. Shahrezaee* Pages 11271142 Abstract Full Text [PDF 369KB]   In this paper، a numerical procedure for an inverse problem of simultaneously determining an unknown coefficient in a semilinear parabolic equation subject to the specification of the solution at an internal point along with the usual initial boundary conditions is considered. The method consists of expanding the required approximate solution as the elements of the inverse quadratic radial basis functions (IQRBFs). The operational matrix of derivative for IQRBFs is introduced and the new computational technique is used for this purpose. The operational matrix of derivative is utilized to reduce the problem to a set of algebraic equations. Some examples are given to demonstrate the validity and applicability of the new method and a comparison is made with the existing results.
Keywords: Collocation, inverse parabolic problem, scattered data, RBFs
  
 Composition operators and natural metrics in meromorphic function classes Qp A. Kamal* Pages 11431154 Abstract Full Text [PDF 121KB]   In this paper، we investigate some results on natural metrics on the μnormal functions and meromorphic Qpclasses. Also، these classes are shown to be complete metric spaces with respect to the corresponding metrics. Moreover، compact composition operators Cϕ and Lipschitz continuous operators acting from μnormal functions to the meromorphic Qpclasses are characterized by conditions depending only on ϕ.
Keywords: Meromorphic classes, composition operators, Lipschitz continuous
  
 Multiplication operators on Banach modules over spectrally separable algebras J. Brač,ič,* Pages 11551167 Abstract Full Text [PDF 133KB]   Let \pA be a commutative Banach algebra and \eX be a left Banach \pAmodule. We study the set \Dec\pA(\eX) of all elements in \pA which induce a decomposable multiplication operator on \eX. In the case \eX=\pA، \Dec\pA(\pA) is the wellknown Apostol algebra of \pA. We show that \Dec\pA(\eX) is intimately related with the largest spectrally separable subalgebra of \pA and in this context we give some results which are related to an open question if Apostol algebra is regular for any commutative algebra \pA .
Keywords: Commutative Banach algebra, decomposable multiplication operator, spectrally separable algebra
  
 On a functional equation for symmetric linear operators on C ∗ algebras A. Taghavi * Pages 11691177 Abstract Full Text [PDF 105KB]   Let A be a C∗ algebra، T:A→A be a linear map which satisfies the functional equation T(x T(y)=T2(xy)،T(x∗)=T(x)∗. We prove that under each of the following conditions، T must be the trivial map T(x)=λx for some λ∈R: i) A is a simple C∗algebra. ii) A is unital with trivial center and has a faithful trace such that each zerotrace element lies in the closure of the span of commutator elements. iii) A=B(H) where H is a separable Hilbert space. For a given field F، we consider a similar functional equation {T(x)T(y)=T2(xy)،T(xtr)= (x)tr،} where T is a linear map on Mn(F) and "tr" is the transpose operator. We prove that this functional equation has trivial solution for all n∈N if and only if F is a formally real field.
Keywords: Functional Equations, C∗,algebras, Formally real fields
  
 The FischerClifford matrices and character table of the maximal subgroup 2 9 :(L 3 (4):S3 ) of U 6 (2):S3 A. L. Prins * Pages 11791195 Abstract Full Text [PDF 170KB]   The full automorphism group of U6(2) is a group of the form U6(2):S3. The group U6(2):S3 has a maximal subgroup 29:(L3(4):S3) of order 61931520. In the present paper، we determine the FischerClifford matrices (which are not known yet) and hence compute the character table of the split extension 29:(L3(4):S3).
Keywords: Coset analysis, Fischer, Clifford matrices, permutation character, fusion map
  
 Some commutativity theorems for ∗ prime rings with (sigma,tau)derivation M. Ashraf * , N. Parveen Pages 11971206 Abstract Full Text [PDF 110KB]   Let R be a ∗prime ring with center Z(R)، d a nonzero (σ،τ)derivation of R with associated automorphisms σ and τ of R، such that σ، τ and d commute with ′∗′. Suppose that U is an ideal of R such that U∗=U، and Cσ،τ={c∈R  cσ(x)=τ(x)c for~all x∈R}. In the present paper، it is shown that if characteristic of R is different from two and [d(U)،d(U)]σ،τ={0}، then R is commutative. Commutativity of R has also been established in case if [d(R)،d(R)]σ،τ⊆Cσ،τ.
Keywords: Prime, rings, derivations, ideal, involution map
  
 Common solutions to pseudomonotone equilibrium problems D. V. Hieu* Pages 12071219 Abstract Full Text [PDF 129KB]   In this paper، we propose two iterative methods for finding a common solution of a finite family of equilibrium problems for pseudomonotone bifunctions. The first is a parallel hybrid extragradientcutting algorithm which is extended from the previously known one for variational inequalities to equilibrium problems. The second is a new cyclic hybrid extragradientcutting algorithm. In the cyclic algorithm، using the known techniques، we can perform and develop practical numerical experiments.
Keywords: Hybrid method, parallel algorithm, cyclic algorithm, extragradient method, equilibrium problem
  
 X injective and Xprojective complexes T. Ö,zen* , E. Yı,ldı,rı,m Pages 12211235 Abstract Full Text [PDF 138KB]   Let X be a class of Rmodules. In this paper، we investigate \;Xinjective (projective) and DGXinjective (projective) complexes which are generalizations of injective (projective) and DGinjective (projective) complexes. We prove that some known results can be extended to the class of \;Xinjective (projective) and DGX injective (projective) complexes for this general settings.
Keywords: Injective (Projective) complex, precover, preenvelope
  
 Sufficient global optimality conditions for general mixed integer nonlinear programming problems J. Quan *, Z. Y. Wu , G. Q. Li Pages 12371246 Abstract Full Text [PDF 111KB]   In this paper، some KKT type sufficient global optimality conditions for general mixed integer nonlinear programming problems with equality and inequality constraints (MINPP) are established. We achieve this by employing a Lagrange function for MINPP. In addition، verifiable sufficient global optimality conditions for general mixed integer quadratic programming problems are derived easily. Numerical examples are also presented.
Keywords: Sufficient global optimality conditions, mixed integer nonlinear programming, mixed integer quadratic programming
  
 A note on FouquetVanherpes question and Fulkerson conjecture F. Chen* Pages 12471258 Abstract Full Text [PDF 120KB]   The excessive index of a bridgeless cubic graph G is the least integer k، such that G can be covered by k perfect matchings. An equivalent form of Fulkerson conjecture (due to Berge) is that every bridgeless cubic graph has excessive index at most five. Clearly، Petersen graph is a cyclically 4edgeconnected snark with excessive index at least 5، so Fouquet and Vanherpe asked whether Petersen graph is the only one with that property. H\"{a}gglund gave a negative answer to their question by constructing two graphs Blowup(K4،C) and Blowup(Prism،C4). Based on the first graph، Esperet et al. constructed infinite families of cyclically 4edgeconnected snarks with excessive index at least five. Based on these two graphs، we construct infinite families of cyclically 4edgeconnected snarks E0،1،2،،(k−1) in which E0،1،2 is Esperet et al.'s construction. In this note، we prove that E0،1،2،3 has excessive index at least five، which gives a strongly negative answer to Fouquet and Vanherpe's question. As a subcase of Fulkerson conjecture، H\"{a}ggkvist conjectured that every cubic hypohamiltonian graph has a Fulkersoncover. Motivated by a related result due to Hou et al.'s، in this note we prove that Fulkerson conjecture holds on some families of bridgeless cubic graphs.
Keywords: Fulkerson, cover, excessive index, snark, hypohamiltonian graph
  
 Operatorvalued tensors on manifolds H. Feizabadi , N. Boroojerdian* Pages 12591277 Abstract Full Text [PDF 167KB]   In this paper we try to extend geometric concepts in the context of operator valued tensors. To this end، we aim to replace the field of scalars R by selfadjoint elements of a commutative C⋆algebra، and reach an appropriate generalization of geometrical concepts on manifolds. First، we put forward the concept of operatorvalued tensors and extend semiRiemannian metrics to operator valued metrics. Then، in this new geometry، some essential concepts of Riemannian geometry such as curvature tensor، LeviCivita connection، Hodge star operator، exterior derivative، divergence،... will be considered.
Keywords: Operator, valued tensors, operator, valued semi, Riemannian metrics, Levi, Civita connection, curvature, Hodge star operator
  
 Irreducible characters of Sylow psubgroups of the Steinberg triality groups 3 D 4 (p 3m ) (Text in Persian) T. Le* Pages 12791291 Abstract Full Text [PDF 137KB]   Here we construct and count all ordinary irreducible characters of Sylow psubgroups of the Steinberg triality groups 3D4(p3m).
Keywords: Irreducible character, root system, Sylow subgroup, Steinberg triality
  
 On list vertex 2arboricity of toroidal graphs without cycles of specific length H. Zhang* Pages 12931303 Abstract Full Text [PDF 193KB]   The vertex arboricity ρ(G) of a graph G is the minimum number of subsets into which the vertex set V(G) can be partitioned so that each subset induces an acyclic graph. A graph G is called list vertex karborable if for any set L(v) of cardinality at least k at each vertex v of G، one can choose a color for each v from its list L(v) so that the subgraph induced by every color class is a forest. The smallest k for a graph to be list vertex karborable is denoted by ρl(G). Borodin، Kostochka and Toft (Discrete Math. 214 (2000) 101112) first introduced the list vertex arboricity of G. In this paper، we prove that ρl(G)≤2 for any toroidal graph without 5cycles. We also show that ρl(G)≤2 if G contains neither adjacent 3cycles nor cycles of lengths 6 and 7.
Keywords: Vertex arboricity, toroidal graph, structure, cycle
  
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