语义网与本体技术导论.ppt

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1、China 2009,http:/www.larkc.eu/,1,语义网与本体技术导论 An Introduction to the Semantic Web and Ontology Technology,黄智生Zhisheng HuangVrije University AmsterdamThe Netherlandshuangcs.vu.nl,China 2009,http:/www.larkc.eu/,2,语义网与本体技术系列讲座,第一部分：导论2009年9月9日星期三14：00-15：30第二部分：逻辑基础2009年9月12日星期六10：00-11：30第三部分：专题研究2009年9

2、月13日星期日14：00-15：30,China 2009,http:/www.larkc.eu/,3,万维网:影响和展望WWW:Its impacts and visions,China 2009,http:/www.larkc.eu/,4,从Google谈起starting from Google,China 2009,http:/www.larkc.eu/,5,存在的问题Existing Problems,China 2009,http:/www.larkc.eu/,6,我们能不能做得更好？Can we do it better?,基于语义的搜索Semantics-based searc

3、h概念组合描述 concept combination specification指定特定领域 domain specific逼近搜索 approximate search搜索代理 search agent,China 2009,http:/www.larkc.eu/,7,语义网(Semantic Web),核心思想:给网络信息赋于确切定义的意义,即语义。The Semantic Web is an extension of the current web in which information is given well-defined meaning,better enabling co

4、mputers and people to work in co-operation.“Berners-Lee et al.,2001,China 2009,http:/www.larkc.eu/,8,语义是什么?What is the Semantics?,Frege(1848-1925):Reference and SenseSyntax,Semantics,PragmaticsDenotational Semantics vs.Operational SemanticsMain features指称性(denotation)唯一性(uniqueness)相关性(relatedness),

5、China 2009,http:/www.larkc.eu/,9,语义网想做什么？(What the Semantic Web wants to do),机器可自动处理机器可理解Content is machine-understandable if it is bound to some formal description of itself(i.e.metadata).,China 2009,http:/www.larkc.eu/,10,HTML标识(HTML Markup),Zhisheng HuangAffiliation:Department of Computer Science

6、Faculty of SciencesVrije University AmsterdamEmail:huang cs.vu.nlPhone:31-20-4447740(office),China 2009,http:/www.larkc.eu/,11,XML标注XML-Annotations,Zhisheng HuangDepartment of Computer ScienceFaculty of SciencesVrije University Amsterdamhuang cs.vu.nl(31)-20-4447740,China 2009,http:/www.larkc.eu/,12

7、,Data Structures,结构化数据Structured Data:Database半结构化数据Semi-structured Data:HTML,XML,BibTex非结构化数据Non-structured Data:Text,China 2009,http:/www.larkc.eu/,13,关系数据库的XML表示XML representation of a relational database,John1234567Mary7654321.,AI group,China 2009,http:/www.larkc.eu/,14,文件类型定义Document Type Defin

8、ition(DTD),China 2009,http:/www.larkc.eu/,15,XML模式XML Schema,The purpose of an XML Schema is to define the legal building blocks of an XML document,just like a DTD.,China 2009,http:/www.larkc.eu/,16,Why XML Schemas,XML Schemas are extensible to future additions XML Schemas are richer and more useful

9、 than DTDs XML Schemas are written in XML XML Schemas support data types XML Schemas support namespaces,China 2009,http:/www.larkc.eu/,17,名字冲突Name Conflicts,Since element names in XML are not fixed,very often a name conflict will occur when two different documents use the same names describing two d

10、ifferent types of elements.If these two XML documents were added together,there would be an element name conflict because both documents contain a same element with different content and definition.,China 2009,http:/www.larkc.eu/,18,XML名字空间XML NameSpace,Using Namespaces to solve Name ConflictsExampl

11、es:xmlns:namespace prefix=namespace xmlns:xsdXMLSchema,China 2009,http:/www.larkc.eu/,19,可扩展标识语言模式XML Schema,China 2009,http:/www.larkc.eu/,20,资源描述框架Resource Description Framework(RDF),Metadata is machine understandable information about web resources or anything that has an URI,it is represented as

12、 a set of independent assertions:,China 2009,http:/www.larkc.eu/,21,RDF:Dublin Core,The Dublin Core provides properties for describing network objects,suitable for use by network search engines.The Dublin Core is a set of predefined properties for describing documents.The first Dublin Core propertie

13、s were defined at the Metadata Workshop in Dublin,Ohio in 1995 and is currently maintained by the Dublin Core Metadata Initiative.,China 2009,http:/www.larkc.eu/,22,Dublin Core Metadata Initiative,The Dublin Core Metadata Initiative is an open forum engaged in the development of interoperable online

14、 metadata standards that support a broad range of purposes and business models.http:/dublincore.org/,China 2009,http:/www.larkc.eu/,23,Annotating Metadata,Guidance on expressing the Dublin Core within the Resource Description Framework(RDF)Eric Miller Paul Miller Dan Brickley Dublin Core;RDF;XML Dub

15、lin Core Metadata Initiative Dublin Core Data Model Working Group 1999-07-01 text/html en,China 2009,http:/www.larkc.eu/,24,资源描述框架模式RDF Schema(RDFS),RDFS defines vocabulary for RDFOrganizes this vocabulary in a typed hierarchyClass,subClassOf,typeProperty,subPropertyOfdomain,range,China 2009,http:/w

16、ww.larkc.eu/,25,RDFS,Prof.Zhong,Zeng，Yi,China 2009,http:/www.larkc.eu/,26,概念与本体Concepts and Ontologies,Philosophical discipline,branch of philosophy that deals with the nature and the organisation of reality.Science of Being(Aristotle,Metaphysics,IV,1)What is being?What are the features common to al

17、l beings?,China 2009,http:/www.larkc.eu/,27,Vocabulary and Ontology,Controlled vocabulary(Jernst 2003):a list of controlled termsunambiguousnon-redundant definitionOntology:a controlled vocabulary expressed in an ontology representation language(Jernst 2003),China 2009,http:/www.larkc.eu/,28,In comp

18、uter science,An ontology is an explicit specification of a conceptualization.Gruber93An ontology is a shared understanding of some domain of interest.Uschold,Gruninger96There are many definitionsa formal specification EXECUTABLEof a conceptualization of a domain COMMUNITYof some part of world that i

19、s of interest APPLICATIONDefinesA common vocabulary of termsSome specification of the meaning of the termsA shared understanding for people and machines,China 2009,http:/www.larkc.eu/,29,Why develop an ontology?,To make domain assumptions explicitEasier to change domain assumptionsEasier to understa

20、nd and update legacy dataTo separate domain knowledge from operational knowledgeRe-use domain and operational knowledge separatelyA community reference for applicationsTo share a consistent understanding of what information means.,China 2009,http:/www.larkc.eu/,30,本体的主要特征Key features of an Ontology,

21、概念层次性Concept hierarchy,概念包含关系concept subsumption,特殊与一般关系 InstanceOf Relation(Instances),部分与整体关系 PartOf Relation(property),China 2009,http:/www.larkc.eu/,31,Why not other alternatives,一阶谓词逻辑 the first-order predicate logic集合论 set theory程序语言 programming languages,China 2009,http:/www.larkc.eu/,32,Chin

22、a 2009,http:/www.larkc.eu/,33,网络本体语言Web Ontology Language(OWL),OWL is built on top of RDF OWL is for processing information on the web OWL was designed to be interpreted by computers OWL was not designed for being read by people OWL is written in XML OWL is a web standard,China 2009,http:/www.larkc.

23、eu/,34,Design Goals for OWL,China 2009,http:/www.larkc.eu/,35,Layered language,OWL Lite:Classification hierarchySimple constraints OWL DL:Maximal expressivenessWhile maintaining tractabilityStandard formalisation OWL Full:Very high expressivenessLoosing tractabilityNon-standard formalisationAll synt

24、actic freedom of RDF(self-modifying),Syntactic layeringSemantic layering,Full,DL,Lite,China 2009,http:/www.larkc.eu/,36,China 2009,http:/www.larkc.eu/,37,China 2009,http:/www.larkc.eu/,38,China 2009,http:/www.larkc.eu/,39,OWL Example:animals,China 2009,http:/www.larkc.eu/,40,China 2009,http:/www.lar

25、kc.eu/,41,网络1.0 Web1.0,China 2009,http:/www.larkc.eu/,42,网络2.0 Web2.0,China 2009,http:/www.larkc.eu/,43,对网络3.0的期待Expectations on Web3.0,新颖性(Novelty)：它不同于已有的Web1.0和Web2.0的技术，它能提供全新的一代网络服务模式(即为什么不是Web1.0或Web2.0）,从字面上看对Web3.0的特征期待：,可行性(Achievability)：它在现有的网络环境下，经过努力是可能实现的，它并不存在不可逾越的技术障碍（即为什么不是Web4.0或更高

26、）。,迫切性(Urgency)：它提供网络服务是当前社会迫切需要的，它的技术引入是能够对社会产生重大影响。（即为什么只能是Web3.0）,China 2009,http:/www.larkc.eu/,44,网络3.0 Web3.0,China 2009,http:/www.larkc.eu/,45,网络1.0 网络2.0 网络3.0Web1.0 Web2.0 Web3.0,网络1.0：文件网 Web1.0:Web of documents网络2.0：人际/社会网 Web2.0:Web of persons网络3.0：数据网 Web3.0:Web of data(semantics),China

27、 2009,http:/www.larkc.eu/,46,网络发展整体观,China 2009,http:/www.larkc.eu/,47,语义联接的好处：从一个实例说起Advantages of Linked Data,China 2009,http:/www.larkc.eu/,48,数据联接的好处：小结,现有的网页是供人们阅读的，不便于机器自动处理，数据联接便于机器自动处理文件联接在局部文字上只允许一个链接，而数据联接对局部文字支持多重链接文件联接只提供部分文字链接，而数据联接保证全文链接基于关键词的搜索引擎如Google虽然看起来支持全文检索，但它不能区分同一个词的不同含义，这对于人

28、名，地名等重复性频率较高的问题领域处理尤其困难，而且在许多具体应用领域一词多义的情形比比皆是。,China 2009,http:/www.larkc.eu/,49,数据联接的统一概念格式,三元组(Triple)方法:例子：提供网络资源的描述能力例子：提供语义的唯一标识让数据内容独立于表达形式提供初步的语义推理能力,China 2009,http:/www.larkc.eu/,50,为什么推理支持是必要的？,例子：从ZhishengHuang是自由大学的雇员和自由大学在阿姆斯特丹，能够推出ZhishengHuang在阿姆斯特丹工作。,-=,China 2009,http:/www.larkc.e

29、u/,51,语义网与本体Semantic Web and Ontologies,China 2009,http:/www.larkc.eu/,52,五句话介绍语义网的主要思想：Why the Semantic Web？,任任何信息系统都需要数据；数数据表示要独立于具体的应用和平台，以保证最大程度地可重用；采用统一的数据概念表示以保证数据表示独立于具体系统（即可采用Triple/Tuple形式）；数数据应能描述网络资源（即要采用RDF/RDFS或其他类似的语言）数数据应提供初步的推理支持（即要采用OWL或其他知识表示语言）（注意；RDF/RDFS/OWL均采用Triple语义模型）,China

30、2009,http:/www.larkc.eu/,53,发展趋势,根据美国著名市场研究公司Gartner的2007五月份报告，到2012年，70%的公开网页将带有一定程度的语义标注，20%将使用更强的基于语义网的本体。Gartner(May 2007):By 2012,70%of public Web pages will have some level of semantic markup,20%will use more extensive Semantic Web-based ontologies”,China 2009,http:/www.larkc.eu/,54,海量语义数据的一部分

31、Ontologies and Metadata:Billion Triples dataset（十亿三元组数据集）,雅虎数据东南大学数据马里兰大学英国open大学SemWebBase（DERI)维基百科地理名字出版物英文语义词典Freebase美国政府数据,China 2009,http:/www.larkc.eu/,55,Linked Data 2009,China 2009,http:/www.larkc.eu/,56,一个具体的数据联接的实例http:/,China 2009,http:/www.larkc.eu/,57,一个具体的数据联接的实例http:/,China 2009,htt

32、p:/www.larkc.eu/,58,Falcons,China 2009,http:/www.larkc.eu/,59,让数据内容独立于表达形式,China 2009,http:/www.larkc.eu/,60,Semantic Web Layers,China 2009,http:/www.larkc.eu/,61,语义网的逻辑基础Logical Foundation of the Semantic Web,描述逻辑与框架逻辑之争Description Logic vs.Frame-Logic封闭世界假说与开放世界假说Closed world assumption vs.Open wo

33、rld assumption唯一名假说与非唯一名假说Unique name assumption vs.Non-unique name assumption面向对象与非面向对象Object-oriented vs.non-object oriented.,China 2009,http:/www.larkc.eu/,62,一个实例,王老师有孩子：王一，王二，王三。问：王老师有几个孩子？,封闭世界与唯一名：3 个,开放世界与唯一名：至少3个,开放世界与非唯一名：至少1个思考：在网络环境下，哪种方式比较合适？,China 2009,http:/www.larkc.eu/,63,语义网应用的一些实例

34、：DBpedia Mobile,http:/beckr.org/DBpediaMobile/?location=Beijinghttp:/beckr.org/DBpediaMobile,China 2009,http:/www.larkc.eu/,64,芬兰医疗语义网HealthFinland Health Information on the Semantic Web,http:/www.seco.tkk.fi/applications/tervesuomi/provide a new kind of solution approach to these problems on a nati

35、onal Finnish level.The system consists of three main components:Metadata,ontology,and service infrastructure.Semantic content creation process.A content creation and harvesting system has been implemented for producing semantically annotated contents,based on the shared metadata model and ontologies

36、.Semantic portal HealthFinland(TerveSuomi)and its services.The material is published via a semantic portal that creates a single national entry-point for health information,health promotion and health-related news.,China 2009,http:/www.larkc.eu/,65,National Semantic Web Ontology Project in Finland(F

37、innONTO),National Semantic Web Ontology Project in Finland(FinnONTO),2003-2007A large national continuation project of FinnONTO,called Semantic Web 2.0(FinnONTO 2.0),started in the beginning of 2008.The research is directed and is mostly carried our by the Semantic Computing Research Group(SeCo)at t

38、he Helsinki University of Technology(TKK)and the University of Helsinki.Also the University of Tampere is contributing to the work.The consortium behind the project included 37 public organizations and companies funding the research during the final year 2007.This consortium represents a wide area o

39、f functions of the society including museums,libraries,business,health organizations,government,media,and education.Public organizations,companies,and universities are participating in the project.,China 2009,http:/www.larkc.eu/,66,荷兰国家文化传承工程The Dutch Cultural Heritage,Eculture ProjectSTiTCH-CatchCh

40、ip Project,China 2009,http:/www.larkc.eu/,67,Project E-Culture,China 2009,http:/www.larkc.eu/,68,China 2009,http:/www.larkc.eu/,69,China 2009,http:/www.larkc.eu/,70,China 2009,http:/www.larkc.eu/,71,China 2009,http:/www.larkc.eu/,72,Timeline,China 2009,http:/www.larkc.eu/,73,2006国际语义网技术挑战赛冠军,China 2009,http:/www.larkc.eu/,74,China 2009,http:/www.larkc.eu/,75,China 2009,http:/www.larkc.eu/,76,China 2009,http:/www.larkc.eu/,77,Questions and Discussions,