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1、AlexanderSchrijverCombinatorialOptimizationPolyhedraandEciencySeptember1,2002SpringerBerlinHeidelbergNewYorkBarcelonaHongKongLondonMilanParisTokyoPrefaceThebookbyGeneLawlerfrom1976wastherstofaseriesofbooksallen-titled`CombinatorialOptimization',someembellishedwithasubtitle
2、:`Net-worksandMatroids',`AlgorithmsandComplexity',`TheoryandAlgorithms'.Whyaddinganotherbooktothisillustriousseries?Thejusticationiscon-tainedinthesubtitleofthepresentbook,`PolyhedraandEciency'.ThisisshorthandforPolyhedralCombinatoricsandEcientAlgorithms.Pioneeredbythewor
3、kofJackEdmonds,polyhedralcombinatoricshasprovedtobeamostpowerful,coherent,andunifyingtoolthroughoutcom-binatorialoptimization.Notonlyithasledtoecient(thatis,polynomial-time)algorithms,butalso,conversely,ecientalgorithmsoftenimplypoly-hedralcharacterizationsandrelatedmin-ma
4、xrelations.Itmakesthetwosidescloselyintertwined.Weaimatoeringbothanintroductiontoandanin-depthsurveyofpoly-hedralcombinatoricsandecientalgorithms.Withinthespanofpolyhedralmethods,wetrytopresentabroadpictureofpolynomial-timesolvablecom-binatorialoptimizationproblems
5、morepre
6、cisely,ofthoseproblemsthathavebeenprovedtobepolynomial-timesolvable.Nexttothat,wegointoafewprominentNP-completeproblemswherepolyhedralmethodsweresuc-cesfulinobtaininggoodboundsandapproximations,likethestablesetandthetravelingsalesmanproblem.Nevertheless,whileweobviouslyhopet
7、hatthequestionNP=P?"willbesettledsoononewayortheother,werealizethatintheastonishingeventthatNP=Pwillbeproved,thisbookwillbehighlyincomplete.Bydenition,beinginPmeansbeingsolvablebya`deterministicse-quentialpolynomial-time'algorithm,andinourdiscussionsofalgorithmsandcomplexi
8、tywerestrictourselvesmainlytothischaracteristic.Asaconse-quence,wedonotcover(butyetoccasionallytouchoroutline)theimportantworkonapproximative,randomized,andparallelalgorithmsandcomplex-ity,areasthatarerecentlyinexcitingmotion.Wealsoneglectapplications,modelling,andcomputatio
9、nalmethodsforNP-completeproblems.Advanceddatastructuresaretreatedonlymodera