Section 6.1 Automorphisms6.1.1 The Automorphism Group of a Graph6.1.2 Graphs with Given GroupFurther Reading6.1.3 Groups of Graph ProductsFurther Reading6.1.4 TransitivityFurther Reading6.1.5 s-Regularity and s-Transitivity6.1.6 Graphical Regular Representations6.1.7 Primitivity6.1.8 More Automorphisms of Infinite GraphsStripsAutomorphisms and Distance6.1.9 DistinguishabilityFurther ReadingDistinguishing Number of Graph ProductsMore Distinguishing Number Results for Infinite GraphsReferencesSection 6.2 Cayley Graphs6.2.1 Construction and Recognition6.2.2 Prevalence6.2.3 Isomorphism6.2.4 Subgraphs6.2.5 Factorization6.2.6 MiscellaneousEmbeddingsApplicationsFurther ReadingReferencesSection 6.3 Enumeration6.3.1 Counting Simple Graphs and MultigraphsLabeled GraphsUnlabeled Graphs6.3.2 Counting Digraphs and TournamentsLabeled DigraphsUnlabeled Digraphs6.3.3 Counting Generic Trees6.3.4 Counting Trees in Chemistry6.3.5 Counting Trees in Computer Science ReferencesSection 6.4 Graphs and Vector Spaces6.4.1 Basic Concepts and DefinitionsSubgraphs and ComplementsComponents, Spanning Trees, and Cospanning TreesCuts and CutsetsVector Space of a Graph under Ring Sum of Its Edge Subsets6.4.2 Circuit Subspace of an Undirected GraphFundamental Circuits and the Dimension of the Circuit Subspace6.4.3 Cutset Subspace of an Undirected GraphFundamental Cutsets and the Dimension of the Cutset Subspace6.4.4 Relationship between Circuit and Cutset SubspacesOrthogonality of Circuit and Cutset SubspacesCirc/Cut-Based Decomposition of Graphs and Subgraphs6.4.5 Circuit and Cutset Spaces in a Directed GraphCircuit and Cut Vectors and MatricesFundamental Circuit, Fundamental Cutset, and Incidence MatricesOrthogonality and the Matrix Tree TheoremMinty’s Painting Theorem6.4.6 Two Circ/Cut-Based Tripartitions of a GraphBicycle-Based TripartitionA Tripartition Based on Maximally Distant Spanning Trees6.4.7 Realization of Circuit and Cutset SpacesWhitney and Kuratowski6.4.8 An Application: Cross-Layer Survivability in a Layered NetworkReferencesSection 6.5 Spectral Graph Theory6.5.1 Basic Matrix Properties6.5.2 Walks and the SpectrumWalks and the Coefficients of the Characteristic PolynomialWalks and the Minimal PolynomialRegular Graphs6.5.3 Line Graph, Root System, Eigenvalue BoundsLine Graphs and Generalized Line GraphsRoot SystemsEigenvalue BoundsFurther Reading6.5.4 Distance-Regular GraphsDistance-Regular Graphs and the Hoffman PolynomialStrongly Regular GraphsFurther Reading6.5.5 Spectral CharacterizationEigenvalues and Graph Operations6.5.6 The LaplacianFurther ReadingReferencesSection 6.6 Matroidal Methods in Graph Theory6.6.1 Matroids: Basic Definitions and Examples6.6.2 Alternative Axiom Systems6.6.3 The Greedy Algorithm6.6.4 Duality6.6.5 Matroid Union and Its Consequences6.6.6 Fundamental Operations6.6.7 Connectedness, 2- and 3-Connectedness for Graphs and MatroidsBounds on the number of elements2-sums and 3-sums6.6.8 Graphs and Totally Unimodular Matrices6.6.9 Excluded-Minor Characterizations6.6.10 Wheels, Whirls, and the Splitter Theorem6.6.11 Removable Circuits6.6.12 Minimally k-connected Graphs and Matroids6.6.13 ConclusionReferencesGlossary for Chapter 6Figure 6.1.1Figure 6.1.2Figure 6.2.1Figure 6.2.2Figure 6.3.1Figure 6.3.2Figure 6.3.3Figure 6.3.4Figure 6.3.5Figure 6.3.6Figure 6.3.7Figure 6.3.8Figure 6.3.9Figure 6.4.1Figure 6.4.2Figure 6.4.3Figure 6.4.4Figure 6.4.5Figure 6.4.6Figure 6.4.7Figure 6.4.8Figure 6.4.9Figure 6.4.10Figure 6.4.11Figure 6.5.1Figure 6.5.2Figure 6.5.3Figure 6.5.4Figure 6.5.5Figure 6.5.6Figure 6.6.1Figure 6.6.2Figure 6.6.3Figure 6.6.4Figure 6.6.5Figure 6.6.6Figure 6.6.7Figure 6.6.8Table 6.3.1Table 6.3.2Table 6.3.3Table 6.3.4Table 6.3.5Table 6.3.6Table 6.3.7Table 6.3.8Table 6.3.9Table 6.3.10Table 6.3.11Table 6.3.12Table 6.3.13Table 6.3.14Table 6.6.1Table 6.6.2Table 6.6.3Table 6.6.4Table 6.6.5Table 6.6.6