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AlgorithmicAspectsofGraphConnectivity
AlgorithmicAspectsofGraphConnectivityisthefirstbookthatthoroughlydiscusses
graphconnectivity,acentralnotioningraphandnetworktheory,emphasizingitsal-
gorithmic aspects. This book contains various definitions of connectivity, including
edge-connectivity,vertex-connectivity,andtheirramifications,aswellasrelatedtop-
ics such as flows and cuts. With wide applications in the fields of communication,
transportation,andproduction,graphconnectivityhasmadetremendousalgorithmic
progressundertheinfluenceoftheoryofcomplexityandalgorithmsinmoderncom-
puter science. New concepts and graph theory algorithms that provide quicker and
moreefficientcomputing,suchasMA(maximumadjacency)orderingofvertices,are
comprehensivelydiscussed.
Covering both basic definitions and advanced topics, this book can be used as a
textbookingraduatecoursesofmathematicalsciences(suchasdiscretemathematics,
combinatorics, and operations research) in addition to being an important reference
bookforallspecialistsworkingindiscretemathematicsanditsapplications.
HiroshiNagamochiisaprofessorattheGraduateSchoolofInformatics,KyotoUniver-
sity.HeisamemberoftheOperationsResearchSocietyofJapanandtheInformation
ProcessingSociety.
ToshihideIbarakiisaprofessorwithKwanseiGakuinUniversityandprofessoremer-
itusofKyotoUniversity.HeisaFellowoftheACM;OperationsResearchSocietyof
Japan;theInstituteofElectronic,InformationandCommunicationEngineers;andthe
InformationProcessingSociety.
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ENCYCLOPEDIA OF MATHEMATICS AND ITS APPLICATIONS
FOUNDING EDITOR G.-C. ROTA
EditorialBoard
R.Doran,P.Flajolet,M.Ismail,T.-Y.Lam,E.Lutwak
Thetitlesbelow,andearliervolumesintheseries,areavailablefrombooksellersorfrom
CambridgeUniversityPressatwww.cambridge.org.
90 M.Lothaire AlgebraicCombinatoricsonWords
91 A.A.IvanovandS.V.Shpectorov GeometryofSporadicGroupsII
92 P.McMullenandE.Schulte AbstractRegularPolytopes
93 G.Gierzetal. ContinuousLatticesandDomains
94 S.Finch MathematicalConstants
95 Y.Jabri TheMountainPassTheorem
96 G.GasperandM.Rahman BasicHypergeometricSeries,2ndedn
97 M.C.PedicchioandW.Tholen(eds.) CategoricalFoundations
98 M.E.H.Ismail ClassicalandQuantumOrthogonalPolynomialsinOneVariable
99 T.Mora SolvingPolynomialEquationSystemsII
100 E.OlivieriandM.Eula´liaVares LargeDeviationsandMetastability
101 A.Kushner,V.Lychagin,andV.Rubtsov ContactGeometryandNonlinear
DifferentialEquations
102 L. W.Beineke,R.J.Wilson,andP.J.Cameron(eds.) TopicsinAlgebraicGraph
Theory
103 O.Staffans Well-PosedLinearSystems
104 J.M.Lewis,S.Lakshmivarahan,andS.Dhall DynamicDataAssimilation
105 M.Lothaire AppliedCombinatoricsonWords
106 A.Markoe AnalyticTomography
107 P.A.Martin MultipleScattering
108 R.A.Brualdi CombinatorialMatrixClasses
110 M.-J.LaiandL.L.Schumaker SplineFunctionsonTriangulations
111 R.T.Curtis SymmetricGenerationofGroups
112 H.Salzmann,T.Grundho¨fer,H.Ha¨hl,andR.Lo¨wen TheClassicalFields
113 S.PeszatandJ.Zabczyk StochasticPartialDifferentialEquationswithLe´vy
Noise
114 J.Beck CombinatorialGames
116 D.Z.ArovandH.Dym J-ContractiveMatrixValuedFunctionsandRelated
Topics
117 R.Glowinski,J.-L.LionsandJ.He ExactandApproximateControllabilityfor
DistributedParameterSystems
118 A.A.BorovkovandK.A.Borovkov AsymptoticAnalysisofRandomWalks
119 M.DezaandM.DutourSikiric´ GeometryofChemicalGraphs
120 T.Nishiura AbsoluteMeasurableSpaces
121 F.King HilbertTransforms
122 S.Khrushchev OrthogonalPolynomialsandContinuedFractions:FromEuler’s
PointofView
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encyclopedia of mathematics and its applications
Algorithmic Aspects of Graph Connectivity
HIROSHI NAGAMOCHI
KyotoUniversity
TOSHIHIDE IBARAKI
KwanseiGakuinUniversity
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CAMBRIDGEUNIVERSITYPRESS
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Informationonthistitle:www.cambridge.org/9780521878647
(cid:1)C HiroshiNagamochiandToshihideIbaraki2008
Thispublicationisincopyright.Subjecttostatutoryexception
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Firstpublished2008
PrintedintheUnitedStatesofAmerica
AcatalogrecordforthispublicationisavailablefromtheBritishLibrary.
LibraryofCongressCataloginginPublicationData
Nagamochi,Hiroshi,1960–
Algorithmicaspectsofgraphconnectivity/HiroshiNagamochiandToshihideIbaraki.
p. cm.
Includesindex.
ISBN978-0-521-87864-7(hardback)
1.Graphconnectivity. 2.Graphalgorithms. I.Ibaraki,Toshihide. II.Title.
QA166.243.N34 2008
511(cid:2).5–dc22 2008007560
ISBN 978-0-521-87864-7hardback
CambridgeUniversityPresshasnoresponsibilityfor
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Contents
Preface pageix
Notation xi
1 Introduction 1
1.1 PreliminariesofGraphTheory 1
1.2 AlgorithmsandComplexities 13
1.3 FlowsandCuts 20
1.4 ComputingConnectivities 34
1.5 RepresentationsofCutStructures 45
1.6 ConnectivitybyTrees 57
1.7 TreeHypergraphs 60
2 MaximumAdjacencyOrderingandForestDecompositions 65
2.1 SpanningSubgraphsPreservingConnectivity 65
2.2 MAOrdering 73
2.3 3-Edge-ConnectedComponents 86
2.4 2-ApproximationAlgorithmsforConnectivity 100
2.5 FastMaximum-FlowAlgorithms 107
2.6 TestingChordality 112
3 MinimumCuts 114
3.1 PendentPairsinMAOrderings 114
3.2 AMinimum-CutAlgorithm 117
3.3 s-Properk-Edge-ConnectedSpanningSubgraphs 119
3.4 AHierarchicalStructureofMAOrderings 123
3.5 MaximumFlowsBetweenaPendentPair 127
3.6 AGeneralizationofPendentPairs 130
3.7 PracticallyEfficientMinimum-CutAlgorithms 131
4 CutEnumeration 137
4.1 EnumeratingAllCuts 137
4.2 EnumeratingSmallCuts 140
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viii Contents
4.3 EnumeratingMinimumCuts 145
4.4 UpperBoundsontheNumberofSmallCuts 149
5 CactusRepresentations 153
5.1 CanonicalFormsofCactusRepresentations 153
5.2 (s,t)-CactusRepresentations 171
5.3 ConstructingCactusRepresentations 180
6 ExtremeVertexSets 191
6.1 ComputingExtremeVertexSetsinGraphs 192
6.2 AlgorithmforDynamicEdgesIncidenttoaSpecifiedVertex 198
6.3 OptimalContractionOrdering 200
6.4 Minimumk-SubpartitionProblem 207
7 EdgeSplitting 217
7.1 Preliminaries 217
7.2 EdgeSplittinginWeightedGraphs 220
7.3 EdgeSplittinginMultigraphs 226
7.4 OtherSplittings 232
7.5 Detachments 237
7.6 ApplicationsofSplittings 240
8 ConnectivityAugmentation 246
8.1 IncreasingEdge-ConnectivitybyOne 247
8.2 StarAugmentation 249
8.3 AugmentingMultigraphs 252
8.4 AugmentingWeightedGraphs 254
8.5 MoreonAugmentation 276
9 SourceLocationProblems 282
9.1 SourceLocationProblemUnderEdge-Connectivity
Requirements 283
9.2 SourceLocationProblemUnderVertex-Connectivity
Requirements 295
10 SubmodularandPosimodularSetFunctions 304
10.1 SetFunctions 304
10.2 MinimizingSubmodularandPosimodularFunctions 306
10.3 ExtremeSubsetsinSubmodularandPosimodularSystems 315
10.4 OptimizationProblemsoverSubmodularandPosimodular
Systems 320
10.5 ExtremePointsofBasePolyhedron 336
10.6 MinimumTransversalinSetSystems 342
Bibliography 357
Index 371
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Preface
Because the concept of a graph was introduced to represent how objects are
connected,itisnotsurprisingthatconnectivityhasbeenacentralnotioningraph
theory since its birth in the 18th century. Various definitions of connectivities
havebeenproposed,forexample,edge-connectivity,vertex-connectivity,andtheir
ramifications.Closelyrelatedtoconnectivityareflowsandcutsingraphs,where
thecutmayberegardedasadualconceptofconnectivityandflows.
A recent general trend in the research of graph theory appears as a shift to
its algorithmic aspects, and improving time and space complexities has been a
strongincentivefordevisingnewalgorithms.Thisisalsotruefortopicsrelatedto
connectivities,flows,andcuts,andmuchimportantprogresshasbeenmade.Such
topicsincludecomputation,enumeration,andrepresentationofallminimumcuts
and small cuts; new algorithms to augment connectivity of a given graph; their
generalization to more abstract mathematical systems; and so forth. In view of
these,itwouldbeatimelyattempttosummarizethoseresultsandpresentthemin
aunifiedsettingsothattheycanbesystematicallyunderstoodandcanbeapplied
tootherrelatedfields.
In these developments, we observe that a simple tool known as maximum
adjacency (MA) ordering has been a profound influence on the computational
complexityofalgorithmsforanumberofproblems.Itisdefinedasfollows.
MA ordering: Given a graph G =(V,E), a total ordering σ =(v ,
1
v2,...,vn) of vertices is an MA ordering if |E(Vi−1,vi)|≥|E(Vi−1,vj)|
holds for all i, j with 2≤i < j ≤n, where V ={v ,v ,...,v } and
i 1 2 i
E(V(cid:2),v)isthesetofedgesfromverticesinV(cid:2) tov.
To our knowledge, MA ordering was first introduced in a paper by R. E. Tarjan
and M.Yannakakis [300],where itwas called theMaximum Cardinality Search
and used to test chordality of graphs, to test acyclicity of hypergraphs, and to
solveotherproblems.WethenrediscoveredMAordering[232],showingthatitis
effectiveforproblemssuchasfindingaforestdecompositionandcomputingthe
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Description:Algorithmic Aspects of Graph Connectivity is the first comprehensive book on this central notion in graph and network theory, emphasizing its algorithmic aspects. Because of its wide applications in the fields of communication, transportation, and production, graph connectivity has made tremendous a