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鹤泳洪
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1 RDF

2 web - Web Grid Web Service - semantic -RDF Semantic Web -

3 Web 1990 Tim Berners-Lee Web HTML Web Web HTML Semantic Web

4 Semantic web web web web -Tim Berners-Lee, James Hendler, Ora Lassila, The Semantic Web, Scientific American, May 2001 The Semantic Web is a major research initiative of the World Wide Web Consortium (W3C) to create a metadata-rich Web of resources that can describe themselves not only by how they should be displayed (HTML) or syntactically (XML), but also by the meaning of the metadata. web W3C (research initiative) web, (HTML) (XML), -From W3C Semantic Web Activity Page Definition: The Semantic Web is the representation of data on the World Wide Web. It is a collaborative effort led by W3C with participation from a large number of researchers and industrial partners. It is based on the Resource Description Framework (RDF), which integrates a variety of applications using XML for syntax and URIs for naming. Semantic Web web W3C Semantic web RDF RDF XML URIs -

5 Semantic Web Web Portal Corporate web site management Enterprise Knowledge Management Document Content Management Intelligent Agent Ubiquitous Computing E-commerce..

6 Semantic web -1 Agent agent semantic web? -Tim Berners-Lee, James Hendler, Ora Lassila, The Semantic Web, Scientific American, May 2001

7 Semantic web :, ; 3. agent : ; 4. agent : - ; 5. agent agent 6. ; 7. -Tim Berners-Lee, James Hendler, Ora Lassila, The Semantic Web, Scientific American, May 2001

8 Semantic Web -Tim Berners-Lee Logic vocabulary Domain vocabulary

9 -> -> -> Logic->Ontology vocabulary-> RDF+RDFS->XML

10 Semantic web Grid Web Service Semantic Syntax Static Semantic Web RDF, RDF Schema, OWL URI, HTML, HTTP World Wide Web Dynamic Intelligent Web DAML-S Rules SOAP, WSDL, UDDI Web Service

11 Semantic web Grid Semantic Web Web Internet Semantic Grid Grid

13 RDF

14 Wittgenstein (1921) stated : Only the sentence has meaning; a name has meaning only in the context of a sentence. A name means an object. The object is its meaning.

15 Real World

16 Real world

18 Virtual World!!!

19 Semantic web Formal System

20 -1

21 -2 Ontology KR frame ontology Logic theory Database schemas ER model Object classes Description logic Collection of terms Ontology Spectrum

22 -3

23 ontology

24 the Science of being

25 Studer ontology conceptualization Phenomenon explicit formal Ontology share Ontology,

26 Semantic Web

27 RDF RDFS OWL/DAML Legend Definition uses the datamodel of RDF Instance Data Defined in terms of Is extension of OWL / DAML RDF Schema RDF

28 RDF RDF : URI XML using an XML-based syntax XML Schema (statements)

29 RDF RDF : Graph data model URI-based vocabulary Datatypes Literals XML serialization syntax Expression of simple facts Entailment

30 RDF Graph Data Model RDF subject predicate object RDF

31 RDF Graph XML serialization <?xml version="1.0"?> <rdf:rdf xmlns:rdf=" xmlns:s=" <rdf:description about=" <s:creator>ora Lassila</s:Creator> </rdf:description> </rdf:rdf>

32 Definitions-1 A subgraph of an RDF graph subset Merge- only merge same uriref Vocabulary set of urirefs An RDF graph is Ground if has no blank nodes Plain if has no literals An instance of an RDF graph A similar graph in which some blank nodes may have been replaced by urirefs A proper instance of a graph At least one blank node have been replaced by urirefs

33 Definitions-2 RDF entailment: an RDF expression A is said to entail another RDF expression B if every possible arrangement of things in the world that makes A true also makes B true. On this basis, if the truth of A is presumed or demonstrated then the truth of B can be inferred.

34 RDF Interpretation RDF RDF

35 Model-Theoretic Semantics Model Theoretic Semantic account of meaning in which Sentence are interpreted in terms of a model of, or abstract formal structure representing, an actual or possible state of the world -Oxford Dictionary, web Model-Theoretic Semantics for the Web -James Farrugia

36 Model Theory language world world FOL World interpretation

37 Model Theoretic Semantic -Statement Model-Theoretic Semantics for the Web -James Farrugia

38 Model Theoretic Semantic Model-theoretic semantics does not pretend, and has no way to determine what certain words and statements "really" mean It offers no help in making the connection between the model (the abstract structure) and the world Model-Theoretic Semantics for the Web -James Farrugia

39 Simple Interpretation A simple interpretation I of a vocabulary V is defined by: A nonempty set IR of resources, called the domain or universe of I. A mapping IEXT from IP into the powerset of IRx(IR union LV) A mapping IS from V into IR LV: set of literal values A non-empty subset IP of IR called Properties A set LV and a mapping XL from literals to LV IP is the set of properties RDF Model Theory-

40 Rules: Determines truth-values of Mapping ground RDF Graph if E is a literal node then I(E) = XL(E) if E is a uriref then I(E) = IS(E) Assign True False value if E is an asserted triple <s, p, o> then I(E) = true if <I(s),I(o)> is in IEXT(I(p)), otherwise I(E)= false. if E is a ground RDF graph then I(E) = false if I(E') = false for some asserted triple E' in E, otherwise I(E) =true. RDF Model Theory-

41 Simple Entailment Graph IS: a->1, b->1, c->2? IR= {1, 2}; IP = {1} Questions <a,b,c>? true <c,a,a>? true <a,c,b>? false IEXT: 1->{<1,2>,<2,1>}

42 RDF Interpretation Example

43 RDF closure The rdf-closure of an RDF graph E is the graph gotten by adding triples to E according to RDF rules. rdf1 xxx aaa yyy. aaa rdf:type rdf:property.

44 RDFS Closure-1 rdf1 xxx aaa yyy aaa rdf:type rdf:property rdfs2 rdfs3 rdfs4a rdfs4b rdfs5 xxx aaa yyy aaa rdfs:domain zzz xxx aaa uuu aaa rdfs:range zzz xxx aaa yyy xxx aaa uuu aaa rdfs:subpropertyof bbb bbb rdfs:subpropertyof ccc xxx rdf:type zzz uuu rdf:type zzz xxx rdf:type rdfs:resource uuu rdf:type rdfs:resource aaa rdfs:subpropertyof ccc

45 RDF Closure-2 rdfs6 xxx aaa yyy aaa rdfs:subpropertyof bbb xxx bbb yyy rdfs7 xxx rdf:type rdfs:class xxx rdfs:subclassof rdfs:resource rdfs8 rdfs9 xxx rdfs:subclassof yyy yyy rdfs:subclassof zzz xxx rdfs:subclassof yyy aaa rdf:type xxx xxx rdfs:subclassof zzz aaa rdf:type yyy

46 Graph Closure An inference engine for RDF -G.Naudts

47 Entailment - statement valid XML entailment

48 web 1! Tim Berners-Lee

49 Web -2 -November 7, 2003 by Clay Shirky Syllogisms are Not Very Useful We Describe The World In Generalities The Semantic Web's Proposed Uses Meta-data is Not A Panacea Ontology is Not A Requirement Artificial Intelligence Reborn Worldviews Differ For Good Reasons Worse is Better

50 Web 3 -November 10, By Paul Ford it is false to call it (semantic web)a machine the method used is usually resolution reasoning (as in Prolog) tableau reasoning, not only syllogism Logic does well in mundane places Top down down top No global ontology world view Meta data and Ontology

c_onto-intro-0304.doc

c_onto-intro-0304.doc 33 9 2 3 1 Semantic Web Ontology WordNet Semantic Web Semantic Web Semantic Web 2001 media Scientific American 2001 2002 The Semantic Web Tim Berners-Lee World Wide Web, WWW WWW RDF, Resource Description