数字地球的关键技术-语义网和OWL简介

数字地球与数字城市的关键技术语义网和OWL简介,数字地球与数字城市讲义之九张雪虎北京大学遥感与GIS研究所2005年11月09日xuehu,概述,语义网简介OWL简介实例演示（ProtgOWL）小结,语义网（SemanticWeb）,TimBerners-Lee推动的互联网2.0版全面应用元数据技术（标识所有的东西）而且是机器可以理解的“元数据”本体技术是实现语义网的核心注意：不要和语义网络（SemanticNetwork）混淆,译自AlanRectoret.al.的OntologyDesignPatternsandProblems,TimBerners-Lee讲故事,TheentertainmentsystemwasbeltingouttheBeatlesWeCanWorkItOutwhenthephonerang.WhenPeteanswered,hisphoneturnedthesounddownbysendingamessagetoalltheotherlocaldevicesthathadavolumecontrol.Hissister,Lucy,wasonthelinefromthedoctorsoffice:Momneedstoseeaspecialistandthenhastohaveaseriesofphysicaltherapysessions.Biweeklyorsomething.Imgoingtohavemyagentsetuptheappointments.Peteimmediatelyagreedtosharethechauffeuring.,FromTBLsScientificAmericanArticle:TheSemanticWeb,2001,TimBerners-Lee讲故事,Atthedoctorsoffice,LucyinstructedherSemanticWebagentthroughherhandheldWebbrowser.TheagentpromptlyretrievedinformationaboutMomsprescribedtreatmentfromthedoctorsagent,lookedupseverallistsofproviders,andcheckedfortheonesin-planforMomsinsurancewithina20-mileradiusofherhomeandwitharatingofexcellentorverygoodontrustedratingservices.Itthenbegantryingtofindamatchbetweenavailableappointmenttimes(suppliedbytheagentsofindividualprovidersthroughtheirWebsites)andPetesandLucysbusyschedules.（Theemphasizedkeywordsindicatetermswhosesemantics,ormeaning,weredefinedfortheagentthroughtheSemanticWeb.）,FromTBLsScientificAmericanArticle:TheSemanticWeb,2001,TimBerners-Lee讲故事,Inafewminutestheagentpresentedthemwithaplan.PetedidntlikeitUniversityHospitalwasallthewayacrosstownfromMomsplace,andhedbedrivingbackinthemiddleofrushhour.Hesethisownagenttoredothesearchwithstricterpreferencesaboutlocationandtime.Lucysagent,havingcompletetrustinPetesagentinthecontextofthepresenttask,automaticallyassistedbysupplyingaccesscertificatesandshortcutstothedataithadalreadysortedthrough.,FromTBLsScientificAmericanArticle:TheSemanticWeb,2001,TimBerners-Lee讲故事,Almostinstantlythenewplanwaspresented:amuchcloserclinicandearliertimesbutthereweretwowarningnotes.First,Petewouldhavetorescheduleacoupleofhislessimportantappointments.Hecheckedwhattheywerenotaproblem.Theotherwassomethingabouttheinsurancecompanyslistfailingtoincludethisproviderunderphysicaltherapists:Servicetypeandinsuranceplanstatussecurelyverifiedbyothermeans,theagentreassuredhim.(Details?)LucyregisteredherassentataboutthesamemomentPetewasmuttering,Sparemethedetails,anditwasallset.(Ofcourse,Petecouldntresistthedetailsandlaterthatnighthadhisagentexplainhowithadfoundthatprovidereventhoughitwasntontheproperlist.),FromTBLsScientificAmericanArticle:TheSemanticWeb,2001,语义网的协议,XML标注的语法XMLSchema标注结构和用词的限制RDF资源（对象）的数据模型（实体关系）RDFSchema描述实体和关系的词汇定义OWL对RDFSchema的扩展描述逻辑（DL）的Web化,译自IvanHerman,W3C的SWQ&A,语义网与AI的关系,语义网采取“主语谓语宾语”的形式一种表达元数据的简单方式结构化和定义名词的方法有限推理与应用相关的规则模糊逻辑AI还包括联想空间推理图像，文字识别复杂的决策流程,译自IvanHerman,W3C的SWQ&A,所以SW只是对AI的一小部分在Web应用中的扩展,语义网与AI的关系,语义网避免了AI中的难题，例如目前的机器还不能很好的理解一副图像或是一篇文章语义网采取的方法是对这些文章和图像进行标注也就是说用元数据弥补AI的不足,译自IvanHerman,W3C的SWQ&A,RDF(ResourceDescriptionFramework),RDF是一组语句，数学上可以表达为:资源：元素，URI.属性:两个资源间的关系（单向）语句:主语（资源）属性（谓语）宾语（资源）RDF是关于这样的语句的通用模型,译自IvanHerman,W3C的SWQ&A,OWL,OWL是对RDF的扩展:定义应用中的术语(ontologies)对属性进行限定(e.g.,cardinalityconstraints)对属性的逻辑特点进行定义(e.g.,transitivity,functionality)定义不同本体之间的对等术语。,译自IvanHerman,W3C的SWQ&A,SWTools,(Graphical)Editors:IsaViz(XeroxResearch/W3C),RDFAuthor(Univ.ofBristol),Protege2000(StanfordUniv.),SWOOP(Univ.ofMaryland),Orient(IBM)IsaViz(XeroxResearch/W3C),RDFAuthor(Univ.ofBristol),Protege2000(StanfordUniv.),SWOOP(Univ.ofMaryland),Orient(IBM)ProgrammingEnvironments:Jena(forJava,includesOWLreasoningandSPARQLqueries),RDFLib(forPython),Redland(inC,withinterfacestoTcl,Java,PHP,Perl,Python,andwithSPARQLqueries),SWI-Prolog,IBMsSemanticToolkit,Jena(forJava,includesOWLreasoning),RDFLib(forPython),Redland(inC,withinterfacestoTcl,Java,PHP,Perl,Python),SWI-Prolog,IBMsSemanticToolkit,Databases(eitherbasedonaninternalsqlengineorfullytriplebased):Kowari,Gateway,Sesame,3Store,JenasJoseki,OracleDatabase10g,RDFandOWLvalidators:W3CsRDFValidator,BBNOWLValidator,PelletOWLReasonerYoucanalwaysstartlookingatW3CsRDFdevelopersite,译自IvanHerman,W3C的SWQ&A,语义网和WebService的关系,静态,500millionusersandmorethan3billionpages,WWWURI,HTML,HTTP,语法,SWandWS,WWWURI,HTML,HTTP,解决的问题informationfinding,informationextraction,informationrepresentation,informationinterpretationandandinformationmaintenance.,SemanticWebRDF,RDF(S),OWL,静态,语法,语义,SWandWS,WWWURI,HTML,HTTP,让网站服务器变成可计算的,SemanticWebRDF,RDF(S),OWL,动态,WebServicesUDDI,WSDL,SOAP,静态,语法,语义,SWandSW,WWWURI,HTML,HTTP,互联网的真正潜力,SemanticWebRDF,RDF(S),OWL,动态,WebServicesUDDI,WSDL,SOAP,静态,IntelligentWebServices,语法,语义,还有许多理论问题待解,开世界vs.闭世界假设,推理的单调性概率方法和模糊逻辑,译自IvanHerman,W3C的SWQ&A,目前SW的科研热点,改善推理算法和实现改善可扩展性（OWLFull）时空推理，模糊逻辑更好的组件化(部分本体的引用和导入）描述逻辑和其他逻辑的关系（Web上的应用）网上本体的管理,译自IvanHerman,W3C的SWQ&A,OWLTheWebOntologyLanguage,W3C标准源于DAML(frames)和Oil(DLsinFrameclothing)建立在RDF-Schema的基础上三种“风味”OWL-Lite简单但是功能有限OWL-DL复杂但是可以支持自动推理OWL-Full高表达能力，但是有逻辑推理问题RusselParadoxetcetc,译自AlanRectoret.al.的OntologyDesignPatternsandProblems,一个简单的例子:动物,LivingThing,Grass,Animal,Plant,Tree,BodyPart,Arm,Leg,Person,Cow,Carnivore,Herbivore,eats,eats,eats,haspart,译自AlanRectoret.al.的OntologyDesignPatternsandProblems,Ontology工程的工具Protg,/index.html,OWL实例演示,NamedClassesandDisjointClassesOWLPropertiesInverseProperties,FunctionalProperties,InverseFunctionalPropertiesTransitiveProperties,SymmetricPropertiesPropertyDomainsandRangesDescribingAndDefiningClassesPropertyRestrictions.ExistentialRestrictionsUsingAReasonerDeterminingtheOWLSub-LanguageInconsistentClassesNecessaryAndSufficientConditions(PrimitiveandDefinedClasses)AutomaticClassificationUniversalRestrictionsAutomaticClassificationandOpenWorldReasoning（ClosureAxioms）ValuePartitions（CoveringAxioms）CardinalityRestrictions,小结,什么是本体技术？什么是语义网技术？什么是OWL语言？如何应用ProtgOWL进行本体建模所有这些与信息智能处理的关系？,作业,请下载到课程网站上下载ProtgOWL相关软件和练习文档。并根据练习文档的步骤在安装的软件中逐一实习。练习文档中说的Racer已经无法下载了，请用网上提供的Pellet引擎。你需要安装JVM，可以到网上下载。解压Pellet包后直接运行Pellet-Dig命令，即可在本机http:/localhost:8081上开启DIG推理引擎服务。GraphViz是观看定义的Ontology图所需软件。所有程序安装后，在Protg菜单Project下的Config中开启OWLWizTab，即可。其他问题可以上网搜索或发邮件问我。,关于课堂热烈讨论的后记,通过今天课堂上和大家的讨论让我明白了一个我课前不明白的东西，所以也是今天课上没有讲清楚的东西。在这里和大家分享：关于任何事物的分类往往都是基于对属