ORIGINAL_ARTICLE ASSOCIATED (SEMI)HYPERGROUPS FROM DUPLEXES In this paper using strongly duplexes we introduce a new class of (semi)hypergroups. The associated (semi)hypergroup from a strongly duplex is called duplex (semi)hypergroup. Two computer programs written in MATLAB show that the two groups \$Z_{2n}\$ and \$Z_{n}times Z_{2}\$ produce a strongly duplex and its associated hypergroup is a complementary feasible hypergroup. http://jas.shahroodut.ac.ir/article_358_f99c12fe0b879e885797880dc7afd9b4.pdf 2015-02-01T11:23:20 2019-05-22T11:23:20 83 96 10.22044/jas.2015.358 Duplexes semihypergroups complementary feasible (semi)hypergroups M. Jafarpour rmo4909@yahoo.com true 1 Department of Mathematics, Vali-e-Asr University of Rafsanjan, Rafsanjan, Iran. Department of Mathematics, Vali-e-Asr University of Rafsanjan, Rafsanjan, Iran. Department of Mathematics, Vali-e-Asr University of Rafsanjan, Rafsanjan, Iran. LEAD_AUTHOR F. Alizadeh falizadeh@yahoo.com true 2 Department of Mathematics, Vali-e-Asr University of Rafsanjan, Rafsanjan, Iran. Department of Mathematics, Vali-e-Asr University of Rafsanjan, Rafsanjan, Iran. Department of Mathematics, Vali-e-Asr University of Rafsanjan, Rafsanjan, Iran. AUTHOR
ORIGINAL_ARTICLE ON THE EDGE COVER POLYNOMIAL OF CERTAIN GRAPHS Let \$G\$ be a simple graph of order \$n\$ and size \$m\$. The edge covering of \$G\$ is a set of edges such that every vertex of \$G\$ is incident to at least one edge of the set. The edge cover polynomial of \$G\$ is the polynomial\$E(G,x)=sum_{i=rho(G)}^{m} e(G,i) x^{i}\$, where \$e(G,i)\$ is the number of edge coverings of \$G\$ of size \$i\$, and\$rho(G)\$ is the edge covering number of \$G\$. In this paper we study the edge cover polynomials of cubic graphs of order \$10\$. We show that all cubic graphs of order \$10\$ (especially the Petersen graph) are determined uniquely by their edge cover polynomials. http://jas.shahroodut.ac.ir/article_359_03bd853b0f975a60d986af404d928abd.pdf 2015-02-01T11:23:20 2019-05-22T11:23:20 97 108 10.22044/jas.2015.359 Edge cover polynomial edge covering equivalence class cubic graph corona S. Alikhani alikhani@yazd.ac.ir true 1 Department of Mathematics, Yazd University, 89195-741, Yazd, Iran. Department of Mathematics, Yazd University, 89195-741, Yazd, Iran. Department of Mathematics, Yazd University, 89195-741, Yazd, Iran. LEAD_AUTHOR S. Jahari s.jahari@gmail.com true 2 Department of Mathematics, Yazd University, 89195-741, Yazd, Iran. Department of Mathematics, Yazd University, 89195-741, Yazd, Iran. Department of Mathematics, Yazd University, 89195-741, Yazd, Iran. AUTHOR
ORIGINAL_ARTICLE ON ANNIHILATOR PROPERTIES OF INVERSE SKEW POWER SERIES RINGS Let \$alpha\$ be an automorphism of a ring \$R\$. The authors [On skew inverse Laurent-serieswise Armendariz rings, Comm. Algebra 40(1) (2012) 138-156] applied the concept of Armendariz rings to inverse skew Laurent series rings and introduced skew inverse Laurent-serieswise Armendariz rings. In this article, we study on aspecial type of these rings and introduce strongly Armendariz rings of inverse skew power series type. We determine the radicals of the inverse skew Laurent series ring \$R((x^{-1};alpha))\$, in terms of those of \$R\$. We also prove that several properties transfer between \$R\$ and the inverse skew Laurent series extension \$R((x^{-1};alpha))\$, in case \$R\$ is a strongly Armendariz ring of inverse skew power series type. http://jas.shahroodut.ac.ir/article_360_3c473d1d286abc25947c292a6b305359.pdf 2015-02-01T11:23:20 2019-05-22T11:23:20 109 124 10.22044/jas.2015.360 Inverse skew power series extensions Radical property Semicommutative rings M. Habibi habibi.mohammad2@gmail.com true 1 Department of Mathematics, University of Tafresh, P.O.Box 39518-79611, Tafresh, Iran. Department of Mathematics, University of Tafresh, P.O.Box 39518-79611, Tafresh, Iran. Department of Mathematics, University of Tafresh, P.O.Box 39518-79611, Tafresh, Iran. LEAD_AUTHOR
ORIGINAL_ARTICLE COHEN-MACAULAY HOMOLOGICAL DIMENSIONS WITH RESPECT TO AMALGAMATED DUPLICATION In this paper we use "ring changed'' Gorenstein homological dimensions to define Cohen-Macaulay injective, projective and flat dimensions. For doing this we use the amalgamated duplication of the base ring with semi-dualizing ideals. Among other results, we prove that finiteness of these new dimensions characterizes Cohen-Macaulay rings with dualizing ideals. http://jas.shahroodut.ac.ir/article_361_50a50dd113314eebf1bad604ed0e91b0.pdf 2015-02-01T11:23:20 2019-05-22T11:23:20 125 135 10.22044/jas.2015.361 Semi-dualizing ideal Amalgamated duplication Gorenstein homological dimension Cohen-Macaulay homological dimension A. Esmaeelnezhad esmaeilnejad@gmail.com true 1 Faculty of Mathematical sciences and computer, University of Kharazmi, Tehran, Iran. Faculty of Mathematical sciences and computer, University of Kharazmi, Tehran, Iran. Faculty of Mathematical sciences and computer, University of Kharazmi, Tehran, Iran. LEAD_AUTHOR
ORIGINAL_ARTICLE COGENERATOR AND SUBDIRECTLY IRREDUCIBLE IN THE CATEGORY OF S-POSETS In this paper we study the notions of cogenerator and subdirectly irreducible in the category of S-poset. First we give somenecessary and sufficient conditions for a cogenerator \$S\$-posets. Then we see that under some conditions, regular injectivity implies generator and cogenerator. Recalling Birkhoff's Representation Theorem for algebra, we study subdirectly irreducible S-posets and give this theorem for the category of ordered right acts over an ordered monoid. Among other things, we give the relations between cogenerators and subdirectly irreducible S-posets. http://jas.shahroodut.ac.ir/article_371_cf285a5a87885ed211e1f128762fbc2f.pdf 2015-02-01T11:23:20 2019-05-22T11:23:20 137 146 10.22044/jas.2015.371 S-poset cogenerator regular injective subdirectly irreducible Gh. Moghaddasi r.moghadasi@hsu.ac.ir true 1 Department of Mathematics, Hakikm Sabzevari University, P.O.Bo 397, Sabzevar, Iran. Department of Mathematics, Hakikm Sabzevari University, P.O.Bo 397, Sabzevar, Iran. Department of Mathematics, Hakikm Sabzevari University, P.O.Bo 397, Sabzevar, Iran. LEAD_AUTHOR
ORIGINAL_ARTICLE ON THE GROUPS WITH THE PARTICULAR NON-COMMUTING GRAPHS Let \$G\$ be a non-abelian finite group. In this paper, we prove that \$Gamma(G)\$ is \$K_4\$-free if and only if \$G cong A times P\$, where \$A\$ is an abelian group, \$P\$ is a \$2\$-group and \$G/Z(G) cong mathbb{ Z}_2 times mathbb{Z}_2\$. Also, we show that \$Gamma(G)\$ is \$K_{1,3}\$-free if and only if \$G cong {mathbb{S}}_3,~D_8\$ or \$Q_8\$. http://jas.shahroodut.ac.ir/article_372_7f1845805d519f0e1594759c85b7ed9d.pdf 2015-02-01T11:23:20 2019-05-22T11:23:20 147 151 10.22044/jas.2015.372 non-commuting graph \$K_4\$-free graph \$K_{1 3}\$-free graph N. Ahanjideh ahanjidn@gmail.com true 1 Department of pure Mathematics, Shahrekord University, P.O.Box 115, Shahrekord, Iran. Department of pure Mathematics, Shahrekord University, P.O.Box 115, Shahrekord, Iran. Department of pure Mathematics, Shahrekord University, P.O.Box 115, Shahrekord, Iran. LEAD_AUTHOR H. Mousavi h.sadat68@yahoo.com true 2 Department of pure Mathematics, Shahrekord University, P.O.Box 115, Shahrekord, Iran. Department of pure Mathematics, Shahrekord University, P.O.Box 115, Shahrekord, Iran. Department of pure Mathematics, Shahrekord University, P.O.Box 115, Shahrekord, Iran. AUTHOR