مرور Volume 43, Issue 7 بر اساس تاریخ انتشار
در حال نمایش موارد 1 - 20 از 34
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On the fixed number of graphs
(Springer and the Iranian Mathematical Society (IMS), 2017-12-01)A set of vertices $S$ of a graph $G$ is called a fixing set of $G$, if only the trivial automorphism of $G$ fixes every vertex in $S$. The fixing number of a graph is the smallest cardinality of a fixing set. The ...
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Distinguishing number and distinguishing index of natural and fractional powers of graphs
(Springer and the Iranian Mathematical Society (IMS), 2017-12-01)The distinguishing number (resp. index) $D(G)$ ($D'(G)$) of a graph $G$ is the least integer $d$ such that $G$ has an vertex labeling (resp. edge labeling) with $d$ labels that is preserved only by a trivial automorphism. ...
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Duality for the class of a multiobjective problem with support functions under $K$-$G_f$-invexity assumptions
(Springer and the Iranian Mathematical Society (IMS), 2017-12-01)In this article, we formulate two dual models Wolfe and Mond-Weir related to symmetric nondifferentiable multiobjective programming problems. Furthermore, weak, strong and converse duality results are established ...
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The ranks of the classes of $A_{10}$
(Springer and the Iranian Mathematical Society (IMS), 2017-12-01)Let $G $ be a finite group and $X$ be a conjugacy class of $G.$ The rank of $X$ in $G,$ denoted by $rank(G{:}X),$ is defined to be the minimal number of elements of $X$ generating $G.$ In this paper we establish the ...
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Recurrences and explicit formulae for the expansion and connection coefficients in series of the product of two classical discrete orthogonal polynomials
(Springer and the Iranian Mathematical Society (IMS), 2017-12-01)Suppose that for an arbitrary function $f(x,y)$ of two discrete variables, we have the formal expansions. [f(x,y)=sumlimits_{m,n=0}^{infty }a_{m,n},P_{m}(x)P_{n}(y),] $$ x^{m}P_{j}(x)=sumlimits_{n=0}^{2m}a_{m,,n} ...
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Limits in modified categories of interest
(Springer and the Iranian Mathematical Society (IMS), 2017-12-01)We firstly prove the completeness of the category of crossed modules in a modified category of interest. Afterwards, we define pullback crossed modules and pullback cat objects that are both obtained by pullback ...
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Characterization of $2times 2$ full diversity space-time codes and inequivalent full rank spaces
(Springer and the Iranian Mathematical Society (IMS), 2017-12-01)In wireless communication systems, space-time codes are applied to encode data when multiple antennas are used in the receiver and transmitter. The concept of diversity is very crucial in designing space-time codes. ...
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A characterization of orthogonality preserving operators
(Springer and the Iranian Mathematical Society (IMS), 2017-12-01)In this paper, we characterize the class of orthogonality preserving operators on an infinite-dimensional Hilbert space $H$ as scalar multiples of unitary operators between $H$ and some closed subspaces of $H$. We ...
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Modules whose direct summands are FI-extending
(Springer and the Iranian Mathematical Society (IMS), 2017-12-01)A module $M$ is called FI-extending if every fully invariant submodule of $M$ is essential in a direct summand of $M$. It is not known whether a direct summand of an FI-extending module is also FI-extending. In this ...
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On subgroups of topologized fundamental groups and generalized coverings
(Springer and the Iranian Mathematical Society (IMS), 2017-12-01)In this paper, we are interested in studying subgroups of topologized fundamental groups and their influences on generalized covering maps. More precisely, we find some relationships between generalized covering ...
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Filter theory in MTL-algebras based on Uni-soft property
(Springer and the Iranian Mathematical Society (IMS), 2017-12-01)The notion of (Boolean) uni-soft filters in MTL-algebras is introduced, and several properties of them are investigated. Characterizations of (Boolean) uni-soft filters are discussed, and some (necessary and ...
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An extension of the Wedderburn-Artin Theorem
(Springer and the Iranian Mathematical Society (IMS), 2017-12-01)In this paper we give conditions under which a ring is isomorphic to a structural matrix ring over a division ring.
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Improved logarithmic-geometric mean inequality and its application
(Springer and the Iranian Mathematical Society (IMS), 2017-12-01)In this short note, we present a refinement of the logarithmic-geometric mean inequality. As an application of our result, we obtain an operator inequality associated with geometric and logarithmic means.
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Zero elements and $z$-ideals in modified pointfree topology
(Springer and the Iranian Mathematical Society (IMS), 2017-12-01)In this paper, we define and study the notion of zero elements in topoframes; a topoframe is a pair $(L, tau)$, abbreviated $L_{ tau}$, consisting of a frame $L$ and a subframe $ tau $ all of whose elements ...
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Localization at prime ideals in bounded rings
(Springer and the Iranian Mathematical Society (IMS), 2017-12-01)In this paper we investigate the sufficiency criteria which guarantee the classical localization of a bounded ring at its prime ideals.
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Characterization of finite $p$-groups by the order of their Schur multipliers ($t(G)=7$)
(Springer and the Iranian Mathematical Society (IMS), 2017-12-01)Let $G$ be a finite $p$-group of order $p^n$ and $|{mathcal M}(G)|=p^{frac{1}{2}n(n-1)-t(G)}$, where ${mathcal M}(G)$ is the Schur multiplier of $G$ and $t(G)$ is a nonnegative integer. The classification of such ...
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Determination of a jump by Fourier and Fourier-Chebyshev series
(Springer and the Iranian Mathematical Society (IMS), 2017-12-01)By observing the equivalence of assertions on determining the jump of a function by its differentiated or integrated Fourier series, we generalize a previous result of Kvernadze, Hagstrom and Shapiro to the whole ...
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Perturbation bounds for $g$-inverses with respect to the unitarily invariant norm
(Springer and the Iranian Mathematical Society (IMS), 2017-12-01)Let complex matrices $A$ and $B$ have the same sizes. Using the singular value decomposition, we characterize the $g$-inverse $B^{(1)}$ of $B$ such that the distance between a given $g$-inverse of $A$ and the set of all ...
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Solving two-dimensional fractional integro-differential equations by Legendre wavelets
(Springer and the Iranian Mathematical Society (IMS), 2017-12-01)In this paper, we introduce the two-dimensional Legendre wavelets (2D-LWs), and develop them for solving a class of two-dimensional integro-differential equations (2D-IDEs) of fractional order. We also investigate ...
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$L^p$ boundedness of the Bergman projection on some generalized Hartogs triangles
(Springer and the Iranian Mathematical Society (IMS), 2017-12-01)In this paper we investigate a two classes of domains in $mathbb{C}^n$ generalizing the Hartogs triangle. We prove optimal estimates for the mapping properties of the Bergman projection on these domains.



