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    Title: 圖之和弦圖數與樹寬
    The Chordality and Treewidth of a Graph
    Authors: 游朝凱
    Contributors: 張宜武
    游朝凱
    Keywords: 和弦圖數
    樹寬
    樹分解
    系列平行圖
    Chordality
    Treewidth
    Tree Decomposition
    Series Parallel Graph
    Date: 2011
    Issue Date: 2016-05-10 19:33:38 (UTC+8)
    Abstract: 對於任何一個圖G = (V;E) ,如果我們可以找到最少的k 個弦圖(V;Ei),使得E = E1 \\ \\ Ek ,則我們定義此圖G = (V;E) 的chordality為k ;而一個圖G = (V;E) 的樹寬則被定義為此圖所有的樹分解的寬的最小值。在這篇論文中,最主要的結論是所有圖的chordality 會小於或等於它的樹寬;更特別的是,有一些平面圖的chordality 為3,而所有系列平行圖的chordality 頂多為2。
    The chordality of a graph G = (V;E) is dened as the minimum k such that we can write E = E1 \\    \\ Ek, where each (V;Ei) is a chordal graph. The treewidth of a graph G = (V;E) is dened to be the minimum width over all tree decompositions of G. In this thesis, the principal result is that the chordality of a graph is at most its treewidth. In particular, there are planar graphs with chordality 3, and series-parallel graphs have chordality at most 2.
    Abstract ii
    中文摘要iii
    1 Introduction 1
    1.1 History of Chordality and Treewidth 1
    1.2 The De nition of Chordality and Treewidth 2
    2 The Chordality of a Graph 6
    2.1 Theorems and Examples of Chordality 6
    2.2 The Counter Example 14
    3 The Treewidth of a Graph 15
    3.1 The Treewidth of Some Classes of Graphs 15
    3.2 The Chordality of K2;2;2 22
    4 Chordality vs. Treewidth 23
    4.1 The Weaker Inequality between Chordality and Treewidth 23
    4.2 Chordality Bounded by Its Treewidth 24
    4.3 The Chordality of Series{Parallel Graphs 37
    References 38
    Reference: [1] L.W. Beineke and R.E. Pippert, Properties and characterizations of k-trees, Mathematika, 18 (1971), 141-151.
    [2] P. Bumeman, A characterization of rigid circuit graphs, Discrete Mathematics, 9 (1974), 205-212.
    [3] M.B. Cozzens and F.S. Roberts, On dimensional properties of graphs, Graphs and Combinatorics, 5 (1989), 29-46.
    [4] G.A. Dirac, A property of 4-chromatic graphs and some remarks on critical graphs, J. London Math. Soc., 27 (1952), 85-92.
    [5] R.J. Dun, Topology of series parallel-networks, J. Math. Anal. Appl., 10 (1965), 303-318.
    [6] F. Gavril, The intersection graphs of subtrees in trees are exactly the chordal graphs, Journal of Combinatorial Theory (B), 16 (1974), 47-56.
    [7] Pinar Heggernes, Treewidth, partial k-trees, and chordal graphs, Delpensum INF 334- Institutt for informatikk, (2006).
    [8] Terry A. McKee and Edward R. Sceinerman, On the Chordality of a Graph, Journal of Graph Theory, 17 (1993), 221-232.
    [9] H.P. Patil, On the structure of k{trees, J. Combin. Inform. System. Sci., 11 (1986), 57-64.
    [10] N. Roberston and P.D. Seymour, Graph minors II: algorithmic aspects of tree width, J. of Algorithms, 7 (1986), 309-322.
    [11] D.J. Rose, On simple characterizations of k-trees, Discrete Math., 7 (1974), 317-322.
    [12] J.R. Walter, Representations of chordal graphs as subtrees of a tree, J. Graph Theory, 2 (1978), 265-267.
    Description: 碩士
    國立政治大學
    應用數學系數學教學碩士在職專班
    98972004
    Source URI: http://thesis.lib.nccu.edu.tw/record/#G0098972004
    Data Type: thesis
    Appears in Collections:[Department of Mathematical Sciences] Theses

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