Iranian Journal of Mathematical Sciences and Informatics
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Iranian Journal of Mathematical Sciences and Informatics - Journal articles for year 2017, Volume 12, Number 1Yektaweb Collection - http://www.yektaweb.comen2017/4/12On Prime and Semiprime Ideals in Ordered AG-Groupoids
http://ijmsi.ir/browse.php?a_id=546&sid=1&slc_lang=en
<p>The aim of this short note is to introduce the concepts of prime and semiprime ideals in ordered AG-groupoids with left identity. These concepts are related to the concepts of quasi-prime and quasi-semiprime ideals, play an important role in studying the structure of ordered AG-groupoids, so it seems to be interesting to study them.</p>
P. YiarayongModeling Dynamic Production Systems with Network Structure
http://ijmsi.ir/browse.php?a_id=467&sid=1&slc_lang=en
<p>This paper deals with the problem of optimizing two-stage structure decision making units (DMUs) where the activity and the performance of two-stage DMU in one period effect on its efficiency in the next period. To evaluate such systems the effect of activities in one period on ones in the next term must be considered. To do so, we propose a dynamic DEA approach to measure the performance of such network units. According to the results of proposed dynamic model the inefficiencies of DMUs improve considerably. Additionally, in models which measure efficiency score, undesirable outputs are mostly treated as inputs, which do not reflect the true production process. We propose an alternative method in dealing with bad outputs. Statistical analysis of sub-efficiencies, i.e. efficiency score of each stage, during all periods represents useful information about the total performance of the stage over all periods.</p>
F. KoushkiA Note on Twists of (y^2=x^3+1)
http://ijmsi.ir/browse.php?a_id=593&sid=1&slc_lang=en
<p>‎‎In the category of Mordell curves (E_D:y^2=x^3+D) with nontrivial torsion groups we find curves of the generic rank two as quadratic twists of (E_1), ‎and of the generic rank at least two and at least three as cubic twists of (E_1). ‎Previous work‎, ‎in the category of Mordell curves with trivial torsion groups‎, ‎has found infinitely many elliptic curves with rank at least seven as sextic twists of (E_1) cite{Kih}.</p>
A. Shamsi ZargarGraph Convergence for H(.,.)-co-Accretive Mapping with over-Relaxed Proximal Point Method for Solving a Generalized Variational Inclusion Problem
http://ijmsi.ir/browse.php?a_id=669&sid=1&slc_lang=en
<p>In this paper, we use the concept of graph convergence of H(.,.)-co-accretive mapping introduced by [R. Ahmad, M. Akram, M. Dilshad, Graph convergence for the H(.,.)-co-accretive mapping with an application, Bull. Malays. Math. Sci. Soc., doi: 10.1007/s40840-014-0103-z, 2014$] and define an over-relaxed proximal point method to obtain the solution of a generalized variational inclusion problem in Banach spaces. Our results can be viewed as an extension of some previously known results in this direction.</p>
R. AhmadIntegrating Differential Evolution Algorithm with Modified Hybrid GA for Solving Nonlinear Optimal Control Problems
http://ijmsi.ir/browse.php?a_id=595&sid=1&slc_lang=en
<p>‎Here‎, ‎we give a two phases algorithm based on integrating differential evolution (DE) algorithm with modified hybrid genetic algorithm (MHGA) for solving the associated nonlinear programming problem of a nonlinear optimal control problem‎. ‎In the first phase‎, ‎DE starts with a completely random initial population where each individual‎, ‎or solution‎, ‎is a random matrix of control input values in time nodes‎. ‎After phase 1‎, ‎to achieve more accurate solutions‎, ‎we increase the number of time nodes‎. ‎The values of the associated new control inputs are estimated by linear or spline interpolations using the curves computed in the phase 1‎. ‎In addition‎, ‎to maintain the diversity in the population‎, ‎some additional individuals are added randomly‎. ‎Next‎, ‎in the second phase‎, ‎MHGA starts by the new population constructed by the above procedure and tries to improve the obtained solutions at the end of phase 1‎. ‎We implement our proposed algorithm on some well-known nonlinear optimal control problems‎. ‎The numerical results show the proposed algorithm can find almost better solution than other proposed algorithms‎.</p>
S. NezhadhoseinSome Families of Graphs whose Domination Polynomials are Unimodal
http://ijmsi.ir/browse.php?a_id=617&sid=1&slc_lang=en
<p>Let $G$ be a simple graph of order $n$. The domination polynomial of $G$ is the polynomial $D(G, x)=sum_{i=gamma(G)}^{n} d(G,i) x^{i}$, where $d(G,i)$ is the number of dominating sets of $G$ of size $i$ and $gamma(G)$ is the domination number of $G$. In this paper we present some families of graphs whose domination polynomials are unimodal.</p>
S. AlikhaniOn Lorentzian two-Symmetric Manifolds of Dimension-four
http://ijmsi.ir/browse.php?a_id=626&sid=1&slc_lang=en
<p>‎We study curvature properties of four-dimensional Lorentzian manifolds with two-symmetry property‎. ‎We then consider Einstein-like metrics‎, ‎Ricci solitons and homogeneity over these spaces‎‎.</p>
A. ZaeimOn the Zero-divisor Cayley Graph of a Finite Commutative Ring
http://ijmsi.ir/browse.php?a_id=632&sid=1&slc_lang=en
<p>Let R be a fnite commutative ring and N(R) be the set of non unit elements of R. The non unit graph of R, denoted by Gamma(R), is the graph obtained by setting all the elements of N(R) to be the vertices and defning distinct vertices x and y to be adjacent if and only if x - yin N(R). In this paper, the basic properties of Gamma(R) are investigated and some characterization results regarding connectedness, girth and planarity of Gamma(R) are given.</p>
A. R. NaghipourOn Open Packing Number of Graphs
http://ijmsi.ir/browse.php?a_id=743&sid=1&slc_lang=en
<p>In a graph G = (V,E), a subset S V is said to be an open packing set if no two vertices of S have a common neighbour in G. The maximum cardinality of an open packing set is called the open packing number and is denoted by rho^o. This paper further studies on this parameter by obtaining some new bounds.</p>
S. SaravanakumarOn Twin-Good Rings
http://ijmsi.ir/browse.php?a_id=638&sid=1&slc_lang=en
<p>In this paper, we investigate various kinds of extensions of twin-good rings. Moreover, we prove that every element of an abelian neat ring R is twin-good if and only if R has no factor ring isomorphic to‌ Z<sub>2</sub> or Z<sub>3</sub>. The main result of [24] states some conditions that any right self-injective ring R is twin-good. We extend this result to any regular Baer ring R by proving that every element of a regular Baer ring is twin-good if and only if R has no factor ring isomorphic to Z<sub>2</sub> or Z<sub>3</sub>. Also we illustrate conditions under which extending modules, continuous modules and some classes of vector space are twin-good.</p>
N. AshrafiAn Interior Point Algorithm for Solving Convex Quadratic Semidefinite Optimization Problems Using a New Kernel Function
http://ijmsi.ir/browse.php?a_id=671&sid=1&slc_lang=en
<p>In this paper, we consider convex quadratic semidefinite optimization problems and provide a primal-dual Interior Point Method (IPM) based on a new kernel function with a trigonometric barrier term. Iteration complexity of the algorithm is analyzed using some easy to check and mild conditions. Although our proposed kernel function is neither a Self-Regular (SR) function nor logarithmic barrier function, the primal-dual IPMs based on this kernel function enjoy the worst case iteration bound $Oleft(sqrt{n}log nlog frac{n}{epsilon}right)$ for the large-update methods with the special choice of its parameters. This bound coincides to the so far best known complexity results obtained from SR kernel functions for linear and semidefinite optimization problems. Finally some numerical issues regarding the practical performance of the new proposed kernel function is reported.</p>
M. R. PeyghamiOn Graded Weakly Classical Prime Submodules
http://ijmsi.ir/browse.php?a_id=918&sid=1&slc_lang=en
<p>Let R be a G-graded ring and M be a G-graded R-module. In this article, we introduce the concept of graded weakly classical prime submodules and give some properties of such submodules.</p>
R. Abu-Dawwas