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1、Semantic Web,Ming Mao,5/31/2019,Semantic Web,2,Outline,Problem and Motivation Semantics and Knowledge Representation Semantic Web,Problem and Motivation,5/31/2019,Semantic Web,4,Finding Ms. Cook,Suppose you wish to find the Ms. Cook No her first name, only her last name, and she worked for one of yo
2、ur clients, and her son was a student at your alma mater, Avondale University,5/31/2019,Semantic Web,5,Web Searches Today,typically turn up innumerable completely irrelevant “hits,“ requiring much manual filtering by the user. Are you looking for a chef? Or information about how to cook something? O
3、r simply a place, person, business or some other entity with “cook“ in its name.,5/31/2019,Semantic Web,6,Problem Current Web,The problem is that the word “cook“ has no meaning, or semantic content, to the computer. Only human can understand it.,5/31/2019,Semantic Web,7,Motivation Semantic Web,How c
4、an we represent these information to be meaningful to machines? In the Semantic Web, the relationship captures the meaning of the links.,5/31/2019,Semantic Web,9,Elaborate, precise automated searches,will be possible only when semantics are widespread on the web. Although the correct combination of
5、that information does not locate on a single web page, semantics make a program to discern the element on various pages, understand relations and piece them together easily, reliably and automatically.,Semantics and Knowledge Representation,5/31/2019,Semantic Web,11,Propositional Representations,Lin
6、coln, who was president of the USA during a bitter war, freed the slaves. A. Lincoln was president of the USA during a war. B. The war was bitter. C. Lincoln freed the slaves. A (president-of, Lincoln, USA, war) B (bitter, war) C (free, Lincoln, slaves),5/31/2019,Semantic Web,12,Propositional Networ
7、k,5/31/2019,Semantic Web,13,Semantic Networks,5/31/2019,Semantic Web,14,Schema,Semantic networks just store properties with concept, there is no approximate nature of our knowledge, like for a HOUSE: Isa : building Parts : rooms Materials : wood, brick, stone Function : human dwelling Shape : rectil
8、inear, triangular Size : 100-10,000 sq. feet Schemas represent categorical knowledge by slot structure. Slots specify values on various attributes.,Semantic Web,5/31/2019,Semantic Web,16,The Semantic Web,Is a simple extension to the current Web. But is not Artificial Intelligence. Not ask machines t
9、o comprehend human language. Only indicate a machines ability to solve a well-defined problem by performing well-defined operations on existing well-defined data.,5/31/2019,Semantic Web,17,The Semantic Web (2),Is “a web of data can be processed directly or indirectly by machines” (Berners-Lee, 2000)
10、 “The Semantic Web is a vision: the idea of having data on the Web defined and linked in a way that it can be used by machines not just for display purposes, but for automation, integration and reuse of data across various applications.” (W3C, 2001),5/31/2019,Semantic Web,18,Semantic Web Principles,
11、Any thing can have a URI#xxx. Vocabularies can merge and be replaced with time Documents are self-describing “Anyone can say anything about anything“ No one system knows everything,5/31/2019,Semantic Web,19,Like the relational database,A record is an RDF node; The field (column) name is RDF property
12、Type; and The record field (table cell) is a value.,5/31/2019,Semantic Web,20,The Element of the Semantic Web,Can share subject, property and/or value across websites using Uniform Resource Identifiers (URIs) Can represent any relational or tree-like data Can be encoded in XML This is called Resourc
13、e Description Framework (RDF),5/31/2019,Semantic Web,21,Semantic Web includes tables,.,5/31/2019,Semantic Web,22,.trees,5/31/2019,Semantic Web,23,. everything,5/31/2019,Semantic Web,24,Berners-Lees Semantic Web Architecture,5/31/2019,Semantic Web,25,Extensible Markup Language (XML),XML is “the unive
14、rsal format for structured documents and data on the Web” (W3C XML Activity Statement) XML is a simplified version of SGML designed to be used on the Internet (Bray etc. 2000) XML companion standards XML Schema Namespace in XML XSLT,5/31/2019,Semantic Web,26,XML Sample, Gable Clark October 25, 2005
15、Mouse 666 $25.00 ,5/31/2019,Semantic Web,27,MetaData,“Metadata is data about data. The term refers to any data used to aid the identification, description and location of networked electronic resources.” (IFLA) Metadata as machine “understandable” semantics of web resources (Lassila, 1998) RDF is a
16、foundation for processing metadata.,5/31/2019,Semantic Web,28,RDF,RDF is a language for representing information about web resources. RDF is designed to be read by computers, not be designed to be displayed to people RDF uses a Uniform Resource Identifier (URI) to identify a web resource and properties to describe the resource RDF uses the terms resources, properties, and values RDF also uses the terms subject, predicates and objects RDF is written in XML and became a W3C recomme
