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Approximation Algorithms for Connected Dominating Sets
 Algorithmica
, 1996
"... The dominating set problem in graphs asks for a minimum size subset of vertices with the following property: each vertex is required to either be in the dominating set, or adjacent to some node in the dominating set. We focus on the question of finding a connected dominating set of minimum size, whe ..."
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Cited by 275 (9 self)
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The dominating set problem in graphs asks for a minimum size subset of vertices with the following property: each vertex is required to either be in the dominating set, or adjacent to some node in the dominating set. We focus on the question of finding a connected dominating set of minimum size, where the graph induced by vertices in the dominating set is required to be connected as well. This problem arises in network testing, as well as in wireless communication. Two polynomial time algorithms that achieve approximation factors of O(H (\Delta)) are presented, where \Delta is the maximum degree, and H is the harmonic function. This question also arises in relation to the traveling tourist problem, where one is looking for the shortest tour such that each vertex is either visited, or has at least one of its neighbors visited. We study a generalization of the problem when the vertices have weights, and give an algorithm which achieves a performance ratio of 3 ln n. We also consider the ...
The NPcompleteness column: an ongoing guide
 Journal of Algorithms
, 1985
"... This is the nineteenth edition of a (usually) quarterly column that covers new developments in the theory of NPcompleteness. The presentation is modeled on that used by M. R. Garey and myself in our book ‘‘Computers and Intractability: A Guide to the Theory of NPCompleteness,’ ’ W. H. Freeman & Co ..."
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Cited by 188 (0 self)
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This is the nineteenth edition of a (usually) quarterly column that covers new developments in the theory of NPcompleteness. The presentation is modeled on that used by M. R. Garey and myself in our book ‘‘Computers and Intractability: A Guide to the Theory of NPCompleteness,’ ’ W. H. Freeman & Co., New York, 1979 (hereinafter referred to as ‘‘[G&J]’’; previous columns will be referred to by their dates). A background equivalent to that provided by [G&J] is assumed, and, when appropriate, crossreferences will be given to that book and the list of problems (NPcomplete and harder) presented there. Readers who have results they would like mentioned (NPhardness, PSPACEhardness, polynomialtimesolvability, etc.) or open problems they would like publicized, should
Greedy Randomized Adaptive Search Procedures For The Steiner Problem In Graphs
 QUADRATIC ASSIGNMENT AND RELATED PROBLEMS, VOLUME 16 OF DIMACS SERIES ON DISCRETE MATHEMATICS AND THEORETICAL COMPUTER SCIENCE
, 1999
"... We describe four versions of a Greedy Randomized Adaptive Search Procedure (GRASP) for finding approximate solutions of general instances of the Steiner Problem in Graphs. Di#erent construction and local search algorithms are presented. Preliminary computational results with one of the versions ..."
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Cited by 104 (30 self)
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We describe four versions of a Greedy Randomized Adaptive Search Procedure (GRASP) for finding approximate solutions of general instances of the Steiner Problem in Graphs. Di#erent construction and local search algorithms are presented. Preliminary computational results with one of the versions on a variety of test problems are reported. On the majority of instances from the ORLibrary, a set of standard test problems, the GRASP produced optimal solutions. On those that optimal solutions were not found, the GRASP found good quality approximate solutions.
Connected Domination and Spanning Trees with Many Leaves
 SIAM J. Discrete Math
, 2000
"... Abstract Let G = (V; E) be a connected graph. A connected dominating set S ae V is a dominating set that induces a connected subgraph of G. The connected domination number of G, denoted fl ..."
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Cited by 15 (2 self)
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Abstract Let G = (V; E) be a connected graph. A connected dominating set S ae V is a dominating set that induces a connected subgraph of G. The connected domination number of G, denoted fl
Strongly orderable graphs  A common generalization of strongly chordal and chordal bipartite graphs
, 2000
"... In this paper those graphs are studied for which a socalled strong ordering of the vertex set exists. This class of graphs, called strongly orderable graphs, generalizes the strongly chordal graphs and the chordal bipartite graphs in a quite natural way. We consider two characteristic elimination o ..."
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Cited by 4 (0 self)
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In this paper those graphs are studied for which a socalled strong ordering of the vertex set exists. This class of graphs, called strongly orderable graphs, generalizes the strongly chordal graphs and the chordal bipartite graphs in a quite natural way. We consider two characteristic elimination orderings for strongly orderable graphs, one on the vertex set and the second on the edge set, and prove that these graphs can be recognized in O(V  + E)V  time. Moreover, a special strong ordering of a strongly orderable graph can be produced in the same time bound. We present variations of greedy algorithms that compute a minimum coloring, a maximum clique, a minimum clique partition and a maximum independent set of a strongly orderable graph in linear time if such a special strong ordering is given. ? 2000 Elsevier Science B.V. All rights reserved. Keywords: Strongly chordal graphs; Chordal bipartite graphs; Strong ordering; Simple elimination ordering; Bisimplicial edge withou...
HTgraphs: centers, connected rdomination and Steiner trees
 COMPUTER SCIENCE JOURNAL OF MOLDOVA
, 1993
"... HTgraphs have been introduced in [11] and investigated with respect to location problems on graphs. In this paper two new characterizations of these graphs are given and then it is shown that the central vertex, connected rdomination and Steiner trees problems are linear or almost linear time solv ..."
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Cited by 4 (2 self)
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HTgraphs have been introduced in [11] and investigated with respect to location problems on graphs. In this paper two new characterizations of these graphs are given and then it is shown that the central vertex, connected rdomination and Steiner trees problems are linear or almost linear time solvable in HTgraphs.
Algorithms
"... In the last quarter of the century there has been a growing interest in the design and analysis of algorithms in different branches of mathematics, science and engineering. In particular, within the past 15 years there has appeared a wealth of literature on algorithms in graph theory, a significant ..."
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Cited by 2 (0 self)
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In the last quarter of the century there has been a growing interest in the design and analysis of algorithms in different branches of mathematics, science and engineering. In particular, within the past 15 years there has appeared a wealth of literature on algorithms in graph theory, a significant part of which is related to domination in graphs. Since there are well over one hundred papers on domination or dominationrelated algorithms, this chapter will necessarily have to focus on a limited collection of these algorithms. The intention of this chapter on domination algorithms for special graph classes is twofold. The major goal is to demonstrate some of the main techniques for designing efficient algorithms for domination problems. For this purpose we consider some particular examples and focus on five graph classes and five well researched variants of the domination problem. Another goal is to present a fairly comprehensive bibliography of algorithms for domination problems. We refer the reader who is unfamiliar with the design and analysis of algorithms to [57].
Steiner trees and Polyhedra
, 1998
"... this paper, we study polyhedra STP(G,S) and CON(G,S). We describe a new class of facet defining inequalities for the STP(G,S) that generalizes the families of constraints so called Steiner partition inequalities and odd hole inequalities introduced by Chopra and Rao [3]. We show that these inequalit ..."
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Cited by 1 (0 self)
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this paper, we study polyhedra STP(G,S) and CON(G,S). We describe a new class of facet defining inequalities for the STP(G,S) that generalizes the families of constraints so called Steiner partition inequalities and odd hole inequalities introduced by Chopra and Rao [3]. We show that these inequalities may define facets for 2trees, which invalidates a conjecture of Chopra and Rao [4]. We also discuss the closely related Steiner connected subgraph polytope. We describe some procedures of construction of facets from facets for CON(G,S). Using this, we obtain a complete description of both CON(G,S) and STP(G,S) for a special case of seriesparallel graphs. Computational applications are also discussed. 2 Valid inequalities
Efficient Algorithms on Asteroidal TripleFree and Distance Hereditary Graphs
, 1993
"... One way of overcoming the intractable nature of problems in graphs is by considering them on special classes of graphs. In this thesis, we study the properties of two important classes of graphs  asteroidal triplefree graphs and distancehereditary graphs, and use their properties to design effici ..."
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One way of overcoming the intractable nature of problems in graphs is by considering them on special classes of graphs. In this thesis, we study the properties of two important classes of graphs  asteroidal triplefree graphs and distancehereditary graphs, and use their properties to design efficient polynomialtime algorithms for a variety of problems that are NP complete on general graphs. Three independent vertices in a graph are said to constitute an asteroidal triple (AT) if there is a path between every two of them that avoids the neighbourhood of the third. Graphs which do not have an AT are said to be ATfree. These graphs strictly contain the wellknown class of cocomparability graphs, but are not necessarily perfect. We present O(n 3 ) algorithms for the problems of finding a minimum cardinality connected dominating set and a Steiner set on these graphs. These are the first known algorithms for these problems on any nontrivial class of nonperfect graphs  in addition...
© 1998 SpringerVerlag New York Inc. Approximation Algorithms for Connected Dominating Sets 1
"... Abstract. The dominating set problem in graphs asks for a minimum size subset of vertices with the following property: each vertex is required to be either in the dominating set, or adjacent to some vertex in the dominating set. We focus on the related question of finding a connected dominating set ..."
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Abstract. The dominating set problem in graphs asks for a minimum size subset of vertices with the following property: each vertex is required to be either in the dominating set, or adjacent to some vertex in the dominating set. We focus on the related question of finding a connected dominating set of minimum size, where the graph induced by vertices in the dominating set is required to be connected as well. This problem arises in network testing, as well as in wireless communication. Two polynomial time algorithms that achieve approximation factors of 2H(�) + 2 and H(�) + 2 are presented, where � is the maximum degree and H is the harmonic function. This question also arises in relation to the traveling tourist problem, where one is looking for the shortest tour such that each vertex is either visited or has at least one of its neighbors visited. We also consider a generalization of the problem to the weighted case, and give an algorithm with an approximation factor of (cn + 1) ln n where cn ln k is the approximation factor for the node weighted Steiner tree problem (currently cn = 1.6103). We also consider the more general problem of finding a connected dominating set of a specified subset of vertices and provide a polynomial time algorithm with a (c + 1)H(�) + c − 1 approximation factor, where c is the Steiner approximation ratio for graphs (currently c = 1.644).