نتایج جستجو برای: cograph
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compiled April 30, 2009 from draft version hg:e0660c153c0b:79 An acyclic coloring of a graph is a proper vertex coloring such that the subgraph induced by the union of any two color classes is a disjoint collection of trees. The more restricted notion of star coloring requires that the union of any two color classes induces a disjoint collection of stars. The acyclic and star chromatic numbers ...
In this paper, we study the parallel and the space complexity of the graph isomorphism problem (GI) for several parameterizations. Let H = {H1,H2, · · · ,Hl} be a finite set of graphs where |V (Hi)| ≤ d for all i and for some constant d. Let G be an H-free graph class i.e., none of the graphs G ∈ G contain any H ∈ H as an induced subgraph. We show that GI parameterized by vertex deletion distan...
A radio labeling of a graph G is an assignment of pairwise distinct, positive integer labels to the vertices of G such that labels of adjacent vertices differ by at least 2. The radio labeling problem (RL) consists in determining a radio labeling that minimizes the maximum label that is used (the so-called span of the labeling). RL is a well-studied problem, mainly motivated by frequency assign...
K. Abe, 27 Y. Hayato, 27 T. Iida, K. Iyogi, J. Kameda, 27 Y. Koshio, 27 Y. Kozuma, Ll. Marti, M. Miura, 27 S. Moriyama, 27 M. Nakahata, 27 S. Nakayama, 27 Y. Obayashi, 27 H. Sekiya, 27 M. Shiozawa, 27 Y. Suzuki, 27 A. Takeda, 27 Y. Takenaga, K. Ueno, K. Ueshima, S. Yamada, T. Yokozawa, C. Ishihara, H. Kaji, T. Kajita, 27 K. Kaneyuki, 27, ∗ K.P. Lee, T. McLachlan, K. Okumura, Y. Shimizu, N. Tani...
Publication of the Oxford Dictionary of National Biography in September 2004 provided among other things an opportunity to take stock of the rise to prominence of medicine and medical history during the twentieth century. Not only are medical figures both well-known and obscure generously scattered throughout the volumes, but the subject itself was promoted to equality with areas such as scienc...
We prove several results about the complexity of the role colouring problem. A role colouring of a graph G is an assignment of colours to the vertices of G such that two vertices of the same colour have identical sets of colours in their neighbourhoods. We show that the problem of finding a role colouring with 1 < k < n colours is NP-hard for planar graphs. We show that restricting the problem ...
A number of problems in computational semantics, group-based collaboration, automated theorem proving, networking, scheduling, and cluster analysis suggested the study of graphs featuring certain \local density" characteristics. Typically, the notion of local density is equated with the absence of chordless paths of length three or more. Recently, a new metric for local density has been propose...
We tested two relevance feedback models, an adaptive linear model and a probabilistic model, using massive feedback query expansion in TREC-5 (Sumner & Shaw, 1997), experimented with a three-valued scale of relevance and reduced feedback query expansion in TREC-6 (Sumner, Yang, Akers & Shaw, 1998), and examined the effectiveness of relevance feedback using a subcollection and the effect of syst...
Extending previous NP-completeness results for the harmonious coloring problem and the pair-complete coloring problem on trees, bipartite graphs and cographs, we prove that these problems are also NP-complete on connected bipartite permutation graphs. We also study the k-path partition problem and, motivated by a recent work of Steiner [G. Steiner, On the k-path partition of graphs, Theoret. Co...
A feedback vertex set F of an undirected graph G is a vertex subset of G whose removal results in a forest. Such a set F is said to be independent if F forms an independent set of G. In this paper, we study the problem of finding an independent feedback vertex set of a given graph with the minimum number of vertices, from the viewpoint of graph classes. This problem is NP-hard even for planar b...
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