語義網(wǎng)與本體技術(shù)導(dǎo)論.ppt

1、China 2009,http:/www.larkc.eu/,1,語義網(wǎng)與本體技術(shù)導(dǎo)論 An Introduction to the Semantic Web and Ontology Technology,黃智生 Zhisheng Huang Vrije University Amsterdam The Netherlands huangcs.vu.nl,China 2009,http:/www.larkc.eu/,2,語義網(wǎng)與本體技術(shù)系列講座,第一部分：導(dǎo)論 2009年9月9日星期三14：00-15：30 第二部分：邏輯基礎(chǔ) 2009年9月12日星期六10：00-11：30 第三部分：專題

2、研究 2009年9月13日星期日14：00-15：30,China 2009,http:/www.larkc.eu/,3,萬維網(wǎng): 影響和展望WWW: Its impacts and visions,China 2009,http:/www.larkc.eu/,4,從Google談起starting from Google,China 2009,http:/www.larkc.eu/,5,存在的問題Existing Problems,China 2009,http:/www.larkc.eu/,6,我們能不能做得更好？Can we do it better?,基于語義的搜索Semantics-

3、based search 概念組合描述 concept combination specification 指定特定領(lǐng)域 domain specific 逼近搜索 approximate search 搜索代理 search agent,China 2009,http:/www.larkc.eu/,7,語義網(wǎng)(Semantic Web),核心思想:給網(wǎng)絡(luò)信息賦于確切定義的意義, 即語義。 The Semantic Web is an extension of the current web in which information is given well-defined meaning,

4、better enabling computers and people to work in co-operation.“Berners-Lee et al., 2001,China 2009,http:/www.larkc.eu/,8,語義是什么?What is the Semantics?,Frege(1848-1925): Reference and Sense Syntax, Semantics, Pragmatics Denotational Semantics vs. Operational Semantics Main features 指稱性 (denotation) 唯一性

5、(uniqueness) 相關(guān)性(relatedness),China 2009,http:/www.larkc.eu/,9,語義網(wǎng)想做什么？(What the Semantic Web wants to do),機(jī)器可自動處理 機(jī)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標(biāo)識(HTML Markup), Zhisheng Huang Affili

6、ation: Department of Computer Science Faculty of Sciences Vrije University Amsterdam Email: huang cs.vu.nl Phone: 31-20-4447740(office) ,China 2009,http:/www.larkc.eu/,11,XML標(biāo)注 XML-Annotations,Zhisheng Huang Department of Computer Science Faculty of Sciences Vrije University Amsterdam huang cs.vu.nl

7、 (31)-20-4447740 ,China 2009,http:/www.larkc.eu/,12,Data Structures,結(jié)構(gòu)化數(shù)據(jù)Structured Data: Database 半結(jié)構(gòu)化數(shù)據(jù)Semi-structured Data: HTML, XML, BibTex 非結(jié)構(gòu)化數(shù)據(jù)Non-structured Data: Text,China 2009,http:/www.larkc.eu/,13,關(guān)系數(shù)據(jù)庫的XML表示XML representation of a relational database, John 1234567 Mary 7654321 . ,AI g

8、roup,China 2009,http:/www.larkc.eu/,14,文件類型定義Document Type Definition(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 ex

9、tensible to future additions XML Schemas are richer and more useful than DTDs XML Schemas are written in XML XML Schemas support data types XML Schemas support namespaces,China 2009,http:/www.larkc.eu/,17,名字沖突Name Conflicts,Since element names in XML are not fixed, very often a name conflict will oc

10、cur when two different documents use the same names describing two different 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/,

11、18,XML名字空間XML NameSpace,Using Namespaces to solve Name Conflicts Examples: xmlns:namespace prefix=namespace xmlns:xsd=/2001/XMLSchema,China 2009,http:/www.larkc.eu/,19,可擴(kuò)展標(biāo)識語言模式 XML Schema, ,China 2009,http:/www.larkc.eu/,20,資源描述框架Resource Description Framework(RDF),Metadata is machi

12、ne understandable information about web resources or anything that has an URI, it is represented as 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. Th

13、e Dublin Core is a set of predefined properties for describing documents. The first Dublin Core properties 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 Initiati

14、ve,The Dublin Core Metadata Initiative is an open forum engaged in the development of interoperable online metadata standards that support a broad range of purposes and business models. /,China 2009,http:/www.larkc.eu/,23,Annotating Metadata, Guidance on expressing the Dublin Cor

15、e within the Resource Description Framework (RDF) Eric Miller Paul Miller Dan Brickley Dublin Core; RDF; XML Dublin Core Metadata Initiative Dublin Core Data Model Working Group 1999-07-01 text/html en ,China 2009,http:/www.larkc.eu/,24,資源描述框架模式RDF Schema (RDFS),RDFS defines vocabulary for RDF Organ

16、izes this vocabulary in a typed hierarchy Class, subClassOf, type Property, subPropertyOf domain, range,China 2009,http:/www.larkc.eu/,25,RDFS,Prof. Zhong,Zeng，Yi,China 2009,http:/www.larkc.eu/,26,概念與本體Concepts and Ontologies,Philosophical discipline, branch of philosophy that deals with the nature

17、and the organisation of reality. Science of Being (Aristotle, Metaphysics, IV,1) What is being? What are the features common to all beings?,China 2009,http:/www.larkc.eu/,27,Vocabulary and Ontology,Controlled vocabulary (Jernst 2003) : a list of controlled terms unambiguous non-redundant definition

18、Ontology: a controlled vocabulary expressed in an ontology representation language (Jernst 2003),China 2009,http:/www.larkc.eu/,28,In computer science ,An ontology is an explicit specification of a conceptualization. Gruber93 An ontology is a shared understanding of some domain of interest. Uschold,

19、 Gruninger96 There are many definitions a formal specification EXECUTABLE of a conceptualization of a domain COMMUNITY of some part of world that is of interest APPLICATION Defines A common vocabulary of terms Some specification of the meaning of the terms A shared understanding for people and machi

20、nes,China 2009,http:/www.larkc.eu/,29,Why develop an ontology?,To make domain assumptions explicit Easier to change domain assumptions Easier to understand and update legacy data To separate domain knowledge from operational knowledge Re-use domain and operational knowledge separately A community re

21、ference for applications To share a consistent understanding of what information means.,China 2009,http:/www.larkc.eu/,30,本體的主要特征Key features of an Ontology,概念層次性Concept hierarchy, 概念包含關(guān)系concept subsumption,特殊與一般關(guān)系 InstanceOf Relation (Instances),部分與整體關(guān)系 PartOf Relation (property),China 2009,http:/w

22、ww.larkc.eu/,31,Why not other alternatives,一階謂詞邏輯 the first-order predicate logic 集合論 set theory 程序語言 programming languages,China 2009,http:/www.larkc.eu/,32,China 2009,http:/www.larkc.eu/,33,網(wǎng)絡(luò)本體語言Web Ontology Language (OWL),OWL is built on top of RDF OWL is for processing information on the web OW

23、L 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.eu/,34,Design Goals for OWL,China 2009,http:/www.larkc.eu/,35,Layered language,OWL Lite: Classification hierarchy Simple constraints OWL

24、DL: Maximal expressiveness While maintaining tractability Standard formalisation OWL Full: Very high expressiveness Loosing tractability Non-standard formalisation All syntactic freedom of RDF(self-modifying),Syntactic layering Semantic layering,Full,DL,Lite,China 2009,http:/www.larkc.eu/,36,China 2

25、009,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.larkc.eu/,41,網(wǎng)絡(luò)1.0 Web1.0,China 2009,http:/www.larkc.eu/,42,網(wǎng)絡(luò)2.0 Web2.0,China 2009,http:/www.larkc.eu/,43,對網(wǎng)絡(luò)3.0的期待Expectation

26、s on Web3.0,新穎性(Novelty)： 它不同于已有的Web1.0和Web2.0的技術(shù)，它能提供全新的一代網(wǎng)絡(luò)服務(wù)模式(即為什么不是Web1.0或Web2.0）,從字面上看對Web3.0的特征期待：,可行性(Achievability)：它在現(xiàn)有的網(wǎng)絡(luò)環(huán)境下，經(jīng)過努力是可能實(shí)現(xiàn)的， 它并不存在不可逾越的技術(shù)障礙（即為什么不是Web4.0或更高）。,迫切性(Urgency)：它提供網(wǎng)絡(luò)服務(wù)是當(dāng)前社會迫切需要的，它的技術(shù)引入是能夠?qū)ι鐣a(chǎn)生重大影響。（即為什么只能是Web3.0）,China 2009,http:/www.larkc.eu/,44,網(wǎng)絡(luò)3.0 Web3.0,China

27、2009,http:/www.larkc.eu/,45,網(wǎng)絡(luò)1.0 網(wǎng)絡(luò)2.0 網(wǎng)絡(luò)3.0Web1.0 Web2.0 Web3.0,網(wǎng)絡(luò)1.0： 文件網(wǎng) Web1.0: Web of documents 網(wǎng)絡(luò)2.0： 人際/社會網(wǎng) Web2.0: Web of persons 網(wǎng)絡(luò)3.0： 數(shù)據(jù)網(wǎng) Web3.0: Web of data (semantics),China 2009,http:/www.larkc.eu/,46,網(wǎng)絡(luò)發(fā)展整體觀,China 2009,http:/www.larkc.eu/,47,語義聯(lián)接的好處：從一個(gè)實(shí)例說起Advantages of Linked Data,C

28、hina 2009,http:/www.larkc.eu/,48,數(shù)據(jù)聯(lián)接的好處：小結(jié),現(xiàn)有的網(wǎng)頁是供人們閱讀的，不便于機(jī)器自動處理，數(shù)據(jù)聯(lián)接便于機(jī)器自動處理 文件聯(lián)接在局部文字上只允許一個(gè)鏈接，而數(shù)據(jù)聯(lián)接對局部文字支持多重鏈接 文件聯(lián)接只提供部分文字鏈接，而數(shù)據(jù)聯(lián)接保證全文鏈接 基于關(guān)鍵詞的搜索引擎如Google雖然看起來支持全文檢索，但它不能區(qū)分同一個(gè)詞的不同含義，這對于人名，地名等重復(fù)性頻率較高的問題領(lǐng)域處理尤其困難，而且在許多具體應(yīng)用領(lǐng)域一詞多義的情形比比皆是。,China 2009,http:/www.larkc.eu/,49,數(shù)據(jù)聯(lián)接的統(tǒng)一概念格式,三元組(Triple)方法: 例

29、子： 提供網(wǎng)絡(luò)資源的描述能力 例子： 提供語義的唯一標(biāo)識 讓數(shù)據(jù)內(nèi)容獨(dú)立于表達(dá)形式 提供初步的語義推理能力,China 2009,http:/www.larkc.eu/,50,為什么推理支持是必要的？,例子：從ZhishengHuang是自由大學(xué)的雇員和自由大學(xué)在阿姆斯特丹，能夠推出ZhishengHuang在阿姆斯特丹工作。 , , - =,China 2009,http:/www.larkc.eu/,51,語義網(wǎng)與本體Semantic Web and Ontologies,China 2009,http:/www.larkc.eu/,52,五句話介紹語義網(wǎng)的主要思想： Why the Se

30、mantic Web？,任任何信息系統(tǒng)都需要數(shù)據(jù)； 數(shù)數(shù)據(jù)表示要獨(dú)立于具體的應(yīng)用和平臺，以保證最大程度地可重用； 采用統(tǒng)一的數(shù)據(jù)概念表示以保證數(shù)據(jù)表示獨(dú)立于具體系統(tǒng)（即可采用Triple/Tuple形式） ； 數(shù)數(shù)據(jù)應(yīng)能描述網(wǎng)絡(luò)資源（即要采用RDF/RDFS或其他類似的語言） 數(shù)數(shù)據(jù)應(yīng)提供初步的推理支持（即要采用OWL或其他知識表示語言） （注意；RDF/RDFS/OWL均采用Triple語義模型）,China 2009,http:/www.larkc.eu/,53,發(fā)展趨勢,根據(jù)美國著名市場研究公司Gartner的2007五月份報(bào)告， 到2012年，70%的公開網(wǎng)頁將帶有一定程度的語義標(biāo)注，

31、20%將使用更強(qiáng)的基于語義網(wǎng)的本體。 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,海量語義數(shù)據(jù)的一部分Ontologies and Metadata: Billion Triples dataset（十億三元組數(shù)據(jù)集）,雅虎數(shù)據(jù) 東南大學(xué)數(shù)據(jù) 馬里蘭大學(xué) 英國open大

32、學(xué) SemWebBase （DERI) 維基百科 地理名字 出版物 英文語義詞典 Freebase 美國政府?dāng)?shù)據(jù),China 2009,http:/www.larkc.eu/,55,Linked Data 2009,China 2009,http:/www.larkc.eu/,56,一個(gè)具體的數(shù)據(jù)聯(lián)接的實(shí)例,China 2009,http:/www.larkc.eu/,57,一個(gè)具體的數(shù)據(jù)聯(lián)接的實(shí)例,China 2009,http:/www.larkc.eu/,58,Falcons,China 2009,http:/www.larkc.eu/,59,讓數(shù)據(jù)內(nèi)容獨(dú)立于表達(dá)形式,China 200

33、9,http:/www.larkc.eu/,60,Semantic Web Layers,China 2009,http:/www.larkc.eu/,61,語義網(wǎng)的邏輯基礎(chǔ)Logical Foundation of the Semantic Web,描述邏輯與框架邏輯之爭 Description Logic vs. Frame-Logic 封閉世界假說與開放世界假說 Closed world assumption vs. Open world assumption 唯一名假說與非唯一名假說 Unique name assumption vs. Non-unique name assumpti

34、on 面向?qū)ο笈c非面向?qū)ο?Object-oriented vs. non-object oriented .,China 2009,http:/www.larkc.eu/,62,一個(gè)實(shí)例,王老師有孩子：王一， 王二，王三。 問：王老師有幾個(gè)孩子？,封閉世界與唯一名： 3 個(gè),開放世界與唯一名：至少3個(gè),開放世界與非唯一名：至少1個(gè) 思考：在網(wǎng)絡(luò)環(huán)境下，哪種方式比較合適？,China 2009,http:/www.larkc.eu/,63,語義網(wǎng)應(yīng)用的一些實(shí)例：DBpedia Mobile,/DBpediaMobile/?location=Beijing http

35、://DBpediaMobile,China 2009,http:/www.larkc.eu/,64,芬蘭醫(yī)療語義網(wǎng)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 national Finnish level. The system consists of three main components:

36、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. Semantic portal HealthFinland (TerveSuomi) and its servic

37、es. 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 (FinnONTO),National Semantic Web Ontology Project in Finland (FinnONTO), 2003-2007 A large national continuation project of FinnONTO, called Semantic Web 2.0 (FinnONTO 2.0), started in the beginning