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Het semantische web, met dank aan het syntactische web Jos Fienieg NGI AIS 27 mei 2009.

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Presentatie over: "Het semantische web, met dank aan het syntactische web Jos Fienieg NGI AIS 27 mei 2009."— Transcript van de presentatie:

1 Het semantische web, met dank aan het syntactische web Jos Fienieg NGI AIS 27 mei 2009

2 Resultaten scan: –Er is veel documentatie beschikbaar. Soms zware kost. –Web 3.0 bestaat niet. Het semantisch web is een beweging, met een verleden (1998), een heden en mogelijk een toekomst. –Het gaat om verwerken en presenteren van data naast het zoeken en presenteren van documenten met tags –Er bestaat brede steun, het kan wat worden. Enkele documenten hierna besproken –De oorspronkelijke ideeën van Tim Berners-Lee en achterliggende concepten –Het semantisch web nu. –De toekomst van het semantisch web

3 Semantic Web Road map Tim Berners-Lee Date: September 1998 Road map: incremental introduction of technology to take us, step by step, from the Web of today to a Web in which machine reasoning will be ubiquitous and devastatingly powerful. Machine-Understandable information: Semantic Web NGI1a-001

4 Semantic Web Road map: architecture Basic assertion model –how should (meta)data be represented –very general,no negation, no implication – RDF (Resource Description Framework) Schema layer: –simple assertions about permitted combinations –e.g. a property is unique (can be used as an identifier) Conversion language (adds implication) –convert a document in one RDF schema into another one Logical layer (first order predicate logic) –allows for checking documents against rules, –e.g. to grant access, to support evolution of rules. Query languages –SQL-like, defined in terms of RDF logic. –A query engine description language would support combining different query engines Digital signature –adds the logic of trust, public key cryptography based NGI1a-001

5 What SW (Semantic Web) can represent Tim Berners-Lee Date: September 1998 Main driving force for SW: express the vast amount of relational database information –A record is an RDF node –The field name is RDF property type –Record field is a value RDF-model very similar to Entrity Relationship model –But on the web a model can be extended by anyone SW builds on Knowledge Representation (KR) experience –KR : SW = hypertext : initial web –remove centralized concepts of absolute truth, total knowledge and total provability SW is not artificial intelligence –RDF will be a complete language: paradox, search of entire internet possible –Application schemas restricted to a deliberately limited language NGI1a-001

6 Meaning is expressed by RDF in sets of triples –subject, verb,object (as in a sentence). –a natural way to describe the vast majority of the data processed by machines. triples can be written using XML tags. subject, verb and object are each identified by a Universal Resource Identifier (URI) –anyone can define a new concept, a new verb, just by defining a URI for it somewhere on the Web NGI1b-001 The Semantic Web By Tim Berners-Lee, James Hendler and Ora Lassila Scientific American Magazine May 2001 Berners-Lee, James Hendler and Ora Lassila

7 The Semantic Web, ScAm 2001 Ontologies and agents Computers will "understand" the meaning of semantic data on a Web page by following links to specified ontologies: –collections of statements written in a language such as RDF define the relations between concepts specify logical rules for reasoning about them.. –most typical: a taxonomy and a set of inference rules. Software agents: provide the real power –Even agents that were not designed to work together can transfer data when the data come with semantics Next step: extend to physical world Composite Capability/Preference Profile (CC/PP): –Standard for descibing functional capabilities of devices –Initially: tailor web content to non standard devices, like cell phones –Later: devices contact other devices or seek for information –E.g. a web-enabled microwave consulting the manufacurers web site for optional cooking parameters NGI1b-001

8 Semantic Web: The Story So Far Ian Horrocks, Un. of Manchester, UK, 2007 Semantic Web research: transform the Web … into a distributed knowledge base and application platform 1st step: develop languages like OWL to capture the knowledge OWL de facto standard for ontology development (geography, geology, astronomy, agriculture, defence, life sciences) Important factor: availability of sophisticated tools with built in reasoning support Recent research: meet challenges associated with large scale applications NGI1c-003

9 OWL, a description logic standard A standard ontology language is a prerequisite to share and exchange meaning. OWL based on OIL, DAML, semantic Networks, KL-ONE Adopt an object-oriented model with individuals, concepts (classes) and roles (relatitionship, property) Concept is atomic or composed from concepts and roles Assertion that a concept is a sub-concept of another, or is exactly equivalent

10 The happy parent This introduces, in standard DL notation, the concept name HappyParent, and asserts that its instances are just those individuals that are instances of Parent, and all of whose children are instances of either intelligent or athletic. the description of HappyParent in OWL’s RDF syntax

11 OWL expressive power OWL is based on a very expressive DL called SHOIN that also provides cardinality restrictions (>, 6) and enumerated classes(called oneOf in OWL). SHOIN also provides for transitive roles

12 Semantic Web Technology (RUG) Jaar: 2008/09 Docent(en): Bouma, dr. G. Onderwerpen: motivatie voor het "semantisch web", en verschillende XML-standaards en technieken (XSLT en XPATH), ontologieen, informatie extractie, en visualisatie (SVG). In projectvorm een applicatie maken het gebied van de Letteren, die gebruik maakt van deze technieken. Verplichte literatuur –Semantic Web: Concepts, Technologies and Applications. –K.K.Breitman, M.A.Casanova, W.Trutzkowskui (Dec 2006) –NASA Monographs in Systems and Software Engineering

13 Semantic Web: Concepts, Technologies and Applications ( Engineering/dp/184628581X Engineering/dp/184628581X



16 Introduction to the Semantic Web Tutorial (selected slides) Linked Data: The Dark Side of the Semantic Web Jim Hendler Rensselaer NGI1c-002 dler_ittsw/iswc08_hendler_ldtdsotsw_01.ppt

17 The excitement is growing… "Data Web" approach finds its use cases in Web Applications (at Web scales) –A lot of data, a little semantics –Finding anything in the mess can be a win! –These are "heuristics" not every answer must be right (qua Google) –But remember time = money! Motivation: the big one for 3.0 is still out there somewhere! –Web 1.0: Google™; Web 2.0: Facebook, Wikipedia … –Web 3.0: not the "Google killer," the next big one

18 Is The Semantic Web Ready for Business? Eran Toch May 2005 Information Systems Engineering Area Faculty of Industrial Engineering and Management Technion – Israel Institute of Technology

19 Markets Niece fields on the general WWW –Content syndication –Communications and social networks Business Processes –Handling interoperability –Extending Service Oriented Architecture (SOA) Knowledge-rich markets –Bioinformatics –Software Engineering –Law Business Intelligence –Business intelligence using semantic annotations

20 Semantic Web Applications Adobe - uses RDF as a basis for documenting meta-data, in PDF and other tools Boeing – uses RDF and OWL in several internal projects AGFA – uses RDF to categorize medical photos NOKIA – lots of Semantic Web activities. Including RDF knowledge store IBM – Strong research activities

21 A Semantic Web Business Case Jeff Pollock, Oracle Corporation on behalf of the W3C Semantic Web Education and Outreach interest group The Semantic Web is a fundamentally unique way of specifying data and data relationships. It is more declarative, more expressive, and more consistently repeatable than Java/C++, Relational Database Management Systems (RDBMS), and XML documents. It builds upon and preserves the conventional data models' respective strengths. This Business Case will articulate why the Semantic Web will: –Empower, directly and indirectly, new business capabilities –Throttle back IT expenditures within medium and large businesses –...By transforming the foundation of enterprise software, and data integration in particular We encourage the reader to take the following actions: –invest in training and skills development now –prototype a solution and explore the new tools now –probe your software vendors about their semantic technology roadmap now –compel your enterprise architects to formulate a multi-year metadata strategy now

22 Beeld uit literatuurscan (1) Doel semantic web ‘beweging’: decentraal beheerde data toegankelijk maken via inter(intra)net, als uitbreiding van het bestaande web. Evidente voordelen –Vollediger inzicht in ‘de toestand van de wereld’ en in wat er in de wereld te koop is (al dan niet via web services) –Toegankelijk voor alles waar een chip in zit (anytime, anywhere) –Informatie en vorm beter toe te snijden op (persoonlijke) behoefte Een onderhoudbaar semantisch web vereist: data, interpreteerbare beschrijving van data (specificatietalen, verzoenen van decentrale begrippenkaders) en vertrouwen. –Met alleen data kun je in het begin wel meters maken, maar je loopt een keer vast. –Degelijk stelsel van specificatietalen beschikbaar (ook bruikbaar zonder web)

23 Beeld uit literatuurscan (2) De semantic web ‘beweging’ bestaat nu meer dan 10 jaar en krijgt (nog steeds) veel steun. Niet meer te stoppen? –W3C, Academisch onderzoek, EU, Belangrijke ICT-leveranciers Opleidingen in basistechnieken beschikbaar op verschillende niveaus Ervaring met applicaties, ontologieën en verzoenen ontologieën groeit, maar is nog mager. –Ervaring met hulpmiddelen voor bouwen en analyseren ontologieën in academische onderzoek Specifieke toepassingen zijn vaak eenvoudiger ter realiseren met bestaande technieken –Ook doordat het semantic web nog jong is. Aansluiten bij de semantic web beweging is een interessante optie –als blijvend aansluiten bij wat elders gebeurt essentieel is –bij een belangrijke informatie-integratie component

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