@Article{Kheirfam2016,
author="Kheirfam, Behrouz",
title="A full Nesterov-Todd step interior-point method for circular cone optimization",
journal="Communications in Combinatorics and Optimization",
year="2016",
volume="1",
number="2",
pages="83-102",
abstract="In this paper, we present a full Newton step feasible interior-pointmethod for circular cone optimization by using Euclidean Jordanalgebra. The search direction is based on the Nesterov-Todd scalingscheme, and only full-Newton step is used at each iteration.Furthermore, we derive the iteration bound that coincides with thecurrently best known iteration bound for small-update methods.",
issn="2538-2128",
doi="10.22049/cco.2016.13554",
url="http://comb-opt.azaruniv.ac.ir/article_13554.html"
}
@Article{Samodivkin2016,
author="Samodivkin, Vladimir",
title="Hypo-efficient domination and hypo-unique domination",
journal="Communications in Combinatorics and Optimization",
year="2016",
volume="1",
number="2",
pages="103-116",
abstract="For a graph $G$ let $gamma (G)$ be its domination number. We define a graph G to be (i) a hypo-efficient domination graph (or a hypo-$mathcal{ED}$ graph) if $G$ has no efficient dominating set (EDS) but every graph formed by removing a single vertex from $G$ has at least one EDS, and (ii) a hypo-unique domination graph (a hypo-$mathcal{UD}$ graph) if $G$ has at least two minimum dominating sets, but $G-v$ has a unique minimum dominating set for each $vin V(G)$. We show that each hypo-$mathcal{UD}$ graph $G$ of order at least $3$ is connected and $gamma(G-v) < gamma(G)$ for all $v in V$. We obtain a tight upper bound on the order of a hypo-$mathcal{P}$ graph in terms of the domination number and maximum degree of the graph, where $mathcal{P} in {mathcal{UD}, mathcal{ED}}$. Families of circulant graphs, which achieve these bounds, are presented. We also prove that the bondage number of any hypo-$mathcal{UD}$ graph is not more than the minimum degree plus one.",
issn="2538-2128",
doi="10.22049/cco.2016.13553",
url="http://comb-opt.azaruniv.ac.ir/article_13553.html"
}
@Article{Alilou2016,
author="Alilou, Abbas
and Amjadi, Jafar",
title="The sum-annihilating essential ideal graph of a commutative ring",
journal="Communications in Combinatorics and Optimization",
year="2016",
volume="1",
number="2",
pages="117-135",
abstract="Let $R$ be a commutative ring with identity. An ideal $I$ of a ring $R$is called an annihilating ideal if there exists $r\in R\setminus \{0\}$ such that $Ir=(0)$ and an ideal $I$ of$R$ is called an essential ideal if $I$ has non-zero intersectionwith every other non-zero ideal of $R$. Thesum-annihilating essential ideal graph of $R$, denoted by $\mathcal{AE}_R$, isa graph whose vertex set is the set of all non-zero annihilating ideals and twovertices $I$ and $J$ are adjacent whenever ${\rm Ann}(I)+{\rmAnn}(J)$ is an essential ideal. In this paper we initiate thestudy of the sum-annihilating essential ideal graph. We first characterize all rings whose sum-annihilating essential ideal graph are stars or complete graphs and then establish sharp bounds on domination number of this graph. Furthermore determine all isomorphism classes of Artinian rings whose sum-annihilating essential ideal graph has genus zero or one.",
issn="2538-2128",
doi="10.22049/cco.2016.13555",
url="http://comb-opt.azaruniv.ac.ir/article_13555.html"
}
@Article{Eliasi2016,
author="Eliasi, Mehdi
and Ghalavand, Ali",
title="On trees and the multiplicative sum Zagreb index",
journal="Communications in Combinatorics and Optimization",
year="2016",
volume="1",
number="2",
pages="137-148",
abstract="For a graph $G$ with edge set $E(G)$, the multiplicative sum Zagreb index of $G$ is defined as$Pi^*(G)=Pi_{uvin E(G)}[d_G(u)+d_G(v)]$, where $d_G(v)$ is the degree of vertex $v$ in $G$.In this paper, we first introduce some graph transformations that decreasethis index. In application, we identify the fourteen class of trees, with the first through fourteenth smallest multiplicative sum Zagreb indeces among all trees of order $ngeq 13$.",
issn="2538-2128",
doi="10.22049/cco.2016.13574",
url="http://comb-opt.azaruniv.ac.ir/article_13574.html"
}
@Article{Atapour2016,
author="Atapour, Maryam
and Khodkar, Abdollah",
title="Twin minus domination in directed graphs",
journal="Communications in Combinatorics and Optimization",
year="2016",
volume="1",
number="2",
pages="149-164",
abstract="Let $D=(V,A)$ be a finite simple directed graph. A function$f:Vlongrightarrow {-1,0,1}$ is called a twin minus dominatingfunction (TMDF) if $f(N^-[v])ge 1$ and $f(N^+[v])ge 1$ for eachvertex $vin V$. The twin minus domination number of $D$ is$gamma_{-}^*(D)=min{w(f)mid f mbox{ is a TMDF of } D}$. Inthis paper, we initiate the study of twin minus domination numbersin digraphs and present some lower bounds for $gamma_{-}^*(D)$ interms of the order, size and maximum and minimum in-degrees andout-degrees.",
issn="2538-2128",
doi="10.22049/cco.2016.13575",
url="http://comb-opt.azaruniv.ac.ir/article_13575.html"
}
@Article{Dehgardi2016,
author="Dehgardi, Nasrin
and Volkmann, Lutz",
title="Signed total Roman k-domination in directed graphs",
journal="Communications in Combinatorics and Optimization",
year="2016",
volume="1",
number="2",
pages="165-178",
abstract="Let $D$ be a finite and simple digraph with vertex set $V(D)$.A signed total Roman $k$-dominating function (STR$k$DF) on$D$ is a function $f:V(D)rightarrow{-1, 1, 2}$ satisfying the conditionsthat (i) $sum_{xin N^{-}(v)}f(x)ge k$ for each$vin V(D)$, where $N^{-}(v)$ consists of all vertices of $D$ fromwhich arcs go into $v$, and (ii) every vertex $u$ for which$f(u)=-1$ has an inner neighbor $v$ for which $f(v)=2$.The weight of an STR$k$DF $f$ is $omega(f)=sum_{vin V (D)}f(v)$.The signed total Roman $k$-domination number $gamma^{k}_{stR}(D)$of $D$ is the minimum weight of an STR$k$DF on $D$. In this paper weinitiate the study of the signed total Roman $k$-domination numberof digraphs, and we present different bounds on $gamma^{k}_{stR}(D)$.In addition, we determine the signed total Roman $k$-dominationnumber of some classes of digraphs. Some of our results are extensionsof known properties of the signed total Roman $k$-dominationnumber $gamma^{k}_{stR}(G)$ of graphs $G$.",
issn="2538-2128",
doi="10.22049/cco.2016.13576",
url="http://comb-opt.azaruniv.ac.ir/article_13576.html"
}