For a fixed positive integer k, a k-tuple total dominating set of a graph G is a set D subset of V (G) such that every vertex of G is adjacent to at least k vertices in D. The k-tuple total domination problem is to de...
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For a fixed positive integer k, a k-tuple total dominating set of a graph G is a set D subset of V (G) such that every vertex of G is adjacent to at least k vertices in D. The k-tuple total domination problem is to determine a minimum k-tuple total dominating set of G. This paper studies k-tuple total domination from an algorithmic point of view. In particular, we present a linear-time algorithm for the k-tuple total domination problem for graphs in which each block is a clique, a cycle or a complete bipartite graph, which include trees, block graphs, cacti and block-cactus graphs. We also establish NP-hardness of the k-tuple total domination problem in undirected path graphs. (C) 2014 Elsevier B.V. All rights reserved.
For a graph G = (V, E), a dominating set is a set D subset of V such that every vertex v is an element of V\D has a neighbor in D. Given a graph G = (V, E) and a positive integer k, the minimum outer-connected dominat...
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For a graph G = (V, E), a dominating set is a set D subset of V such that every vertex v is an element of V\D has a neighbor in D. Given a graph G = (V, E) and a positive integer k, the minimum outer-connected dominating set problem for G is to decide whether G has a dominating set D of cardinality at most k such that G[V\D] , the induced subgraph by G on V\D, is connected. In this paper, we consider the complexity of the minimum outer-connected dominating set problem for the class of chordal graphs. In particular, we show that the minimum outer-connected dominating set problem is NP-complete for doubly chordal graphs and undirected path graphs, two well studied subclasses of chordal graphs. We also give a linear time algorithm for computing a minimum outer-connected dominating set in proper interval graphs. Notice that proper interval graphs form a subclass of undirected path graphs as well as doubly chordal graphs. Crown Copyright (C) 2013 Published by Elsevier B.V. All rights reserved.
Suppose G = (V, E) is a simple graph and k is a fixed positive integer. A subset D subset of V is a distance k-dominating set of G if for every u is an element of V. there exists a vertex v is an element of D such tha...
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Suppose G = (V, E) is a simple graph and k is a fixed positive integer. A subset D subset of V is a distance k-dominating set of G if for every u is an element of V. there exists a vertex v is an element of D such that d(G)(u, v) <= k, where d(G)(u, v) is the distance between u and v in G. A set D subset of V is a distance k-paired-dominating set of G if D is a distance k-dominating set and the induced subgraph G[D] contains a perfect matching. Given a graph G = (V, E) and a fixed integer k > 0, the MIN DISTANCE k-PAIRED-DOM SET problem is to find a minimum cardinality distance k-paired-dominating set of G. In this paper, we show that the decision version of MIN DISTANCE k-PAIRED-DOM SET iS NP-complete for undirected path graphs. This strengthens the complexity of decision version Of MIN DISTANCE k-PAIRED-DOM SET problem in chordal graphs. We show that for a given graph G, unless NP subset of DTIME (n(0)((log) (log) (n)) MIN DISTANCE k-PAIRED-Dom SET problem cannot be approximated within a factor of (1 -epsilon ) In n for any epsilon > 0, where n is the number of vertices in G. We also show that MIN DISTANCE k-PAIRED-DOM SET problem is APX-complete for graphs with degree bounded by 3. On the positive side, we present a linear time algorithm to compute the minimum cardinality of a distance k-paired-dominating set of a strongly chordal graph G if a strong elimination ordering of G is provided. We show that for a given graph G, MIN DISTANCE k-PAIRED-DOM SET problem can be approximated with an approximation factor of 1 + In 2 + k . In(Delta(G)), where Delta(G) denotes the maximum degree of G. (C) 2012 Elsevier B.V All rights reserved.
Suppose G=(V,E) is a graph in which each maximal clique C-i is associated with an integer r(i), where 0 less than or equal to r(i) less than or equal to\C-i\. The generalized clique transversal problem is to determine...
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Suppose G=(V,E) is a graph in which each maximal clique C-i is associated with an integer r(i), where 0 less than or equal to r(i) less than or equal to\C-i\. The generalized clique transversal problem is to determine the minimum cardinality of a subset D of V such that \D boolean AND C-i\greater than or equal to r(i) for every maximal clique C-i of G. The problem includes the clique-transversal problem, the i,1 clique-cover problem, and for perfect graphs, the maximum q-colorable subgraph problems as special cases. This paper gives complexity results for the problem on subclasses of chordal graphs, e.g., strongly chordal graphs, k-trees, split graphs, and undirected path graphs.
Bertossi and Bonuccelli (1986) proved that the Hamiltonian Circuit Problem is NP-complete even when the inputs are restricted to the special class of undirected path graphs. The corresponding problem on directed path ...
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Bertossi and Bonuccelli (1986) proved that the Hamiltonian Circuit Problem is NP-complete even when the inputs are restricted to the special class of undirected path graphs. The corresponding problem on directed pathgraphs was left as an open problem. We use a characterization of directed pathgraphs due to Monma and Wei (1986) to prove that the Hamiltonian Circuit Problem and the Hamiltonian path Problem are NP-complete on directed pathgraphs.
We consider the problem of finding a Hamiltonian circuit in some classes of intersection graphs which generalize interval graphs. We show that the problem is NP-complete for undirected path graphs (and hence chordal g...
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We consider the problem of finding a Hamiltonian circuit in some classes of intersection graphs which generalize interval graphs. We show that the problem is NP-complete for undirected path graphs (and hence chordal graphs), double interval graphs, and rectangle graphs.
A set of vertices D is a dominating set for a graph if every vertex is either in D or adjacent to a vertex which is in D. We show that the problem of finding a minimum dominating set in a chordal graph is NP-complete,...
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A set of vertices D is a dominating set for a graph if every vertex is either in D or adjacent to a vertex which is in D. We show that the problem of finding a minimum dominating set in a chordal graph is NP-complete, even when restricted to undirected path graphs, but exhibit a linear time greedy algorithm for the problem further restricted to directed pathgraphs. Streamlined to handle only trees, our algorithm becomes the algorithm of Cockayne, Goodman and Hedetniemi. An interesting parallel with graph isomorphism is pointed out.
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