1 Berendt: Knowledge and the Web, 1st semester 2016/2017, 1 Knowledge and the Web – The Semantic Web (1) Bettina Berendt KU Leuven, Department of Computer Science Last update: 5 October 2016

2 Berendt: Knowledge and the Web, 1st semester 2016/2017, 2 Agenda The Semantic Web: Motivation and overview Semantics, concepts and ontologies Very brief recap of XML (& why it’s not semantic) RDF and RDFS Linked (Open) Data (LOD)

3 Berendt: Knowledge and the Web, 1st semester 2016/2017, 3 What is a database? – from the intro slides of the Bachelor course A set of centrally managed, permanently stored data, which always have to be available to different applications All data that are relevant for all previewed applications Every application sees/access only relevant data Different applications share the same data 3 How to make this worldwide? … and apply some necessary changes: decentrally managed, maybe even conceptualised data may be transitory availability may change

4 Berendt: Knowledge and the Web, 1st semester 2016/2017, 4 Well, that exists

5 Berendt: Knowledge and the Web, 1st semester 2016/2017, 5 From Web of documents to Web of data WWW: human-understandable information Semantic Web: machine-processable information

6 Berendt: Knowledge and the Web, 1st semester 2016/2017, 6 What could data in such huge databases be about? For example, 1.71 billion people. Reports-Second-Quarter-2016-Results/default.aspx

7 Berendt: Knowledge and the Web, 1st semester 2016/2017, 7 Who are such databases interesting for? Examples (1)

8 Berendt: Knowledge and the Web, 1st semester 2016/2017, 8 Who are such databases interesting for? Examples (2)

9 Berendt: Knowledge and the Web, 1st semester 2016/2017, 9 Why … … should one company own all the data / be able to monetize it? … should one company be able to determine the data schema?  Decentralisation! (Whether this addresses the surveillance problem is another question. We’ll return to this later.)

10 Berendt: Knowledge and the Web, 1st semester 2016/2017,

11 Berendt: Knowledge and the Web, 1st semester 2016/2017, 11 The original vision The entertainment system was belting out the Beatles' "We Can Work It Out" when the phone rang. When Pete answered, his phone turned the sound down by sending a message to all the other local devices that had a volume control. His sister, Lucy, was on the line from the doctor's office: "Mom needs to see a specialist and then has to have a series of physical therapy sessions. Biweekly or something. I'm going to have my agent set up the appointments." Pete immediately agreed to share the chauffeuring. At the doctor's office, Lucy instructed her Semantic Web agent through her handheld Web browser. The agent promptly retrieved information about Mom's prescribed treatment from the doctor's agent, looked up several lists of providers, and checked for the ones in-plan for Mom's insurance within a 20-mile radius of her home and with a rating of excellent or very good on trusted rating services. It then began trying to find a match between available appointment times (supplied by the agents of individual providers through their Web sites) and Pete's and Lucy's busy schedules. (The emphasized keywords indicate terms whose semantics, or meaning, were defined for the agent through the Semantic Web.) Tim Berners-Lee, James Hendler and Ora Lassila (2001). The Semantic Web. A new form of Web content that is meaningful to computers will unleash a revolution of new possibilities. Scientific American. available at

12 Berendt: Knowledge and the Web, 1st semester 2016/2017, 12 The Semantic Web and Linked Data: overview (1) n The semantic web is an evolving extension of the World Wide Web in which web content can be expressed not only in natural language, but also in a format that can be read and used by software agents, thus permitting them to find, share and integrate information more easily.World Wide Webweb contentnatural languageread software agentsintegrate n It derives from W3C director Sir Tim Berners-Lee's vision of the Web as a universal medium for data, information, and knowledge exchange.W3CSir Tim Berners-Leedatainformationknowledge n At its core, the semantic web comprises a philosophy, a set of design principles, collaborative working groups, and a variety of enabling technologies.working groups n Some elements of the semantic web are expressed as prospective future possibilities that have yet to be implemented or realized. n Other elements of the semantic web are expressed in formal specifications.

13 Berendt: Knowledge and the Web, 1st semester 2016/2017, 13 The Semantic Web and Linked Data: overview (2) n Other elements of the semantic web are expressed in formal specifications. n Some of these include Resource Description Framework (RDF), a variety of data interchange formats (e.g. RDF/XML, N3, Turtle, N- Triples), and notations such as RDF Schema (RDFS) and the Web Ontology Language (OWL), all of which are intended to provide a formal description of concepts, terms, and relationships within a given knowledge domain.Resource Description FrameworkRDF/XMLN3TurtleN- TriplesRDF SchemaWeb Ontology Language formal descriptionconceptstermsrelationshipsknowledge domain n “The Semantic Web is a big fancy term for a Web with data. We have HTML for the Web of documents that we can read. We have the Semantic Web for a Web of linked data. It's very similar in that there are pieces of information out there, except that they're put there in a way that it's easy for machines to use. People can use them, but they have to use tools like spreadsheets, and so on. “ (TBL 2012 interview, see references)

14 Berendt: Knowledge and the Web, 1st semester 2016/2017, 14 The Semantic Web layer cake (T. Berners-Lee talk at XML 2000) RDF: W3C Rec OWL: W3C Rec OWL2: W3C Rec. 2009

15 Berendt: Knowledge and the Web, 1st semester 2016/2017, ★ Open Data: Formats example

16 Berendt: Knowledge and the Web, 1st semester 2016/2017, ★ Open Data (Berners-Lee, 2006)

17 Berendt: Knowledge and the Web, 1st semester 2016/2017, 17 Does this exist? Example “Marie Curie“ This contains many links to DBPedia itself (e.g. dbo:... ), but also to other LOD datasets – for example, the resources prefixed by yago: (see and-information-systems/research/yago-naga/yago//) and-information-systems/research/yago-naga/yago// freebase: (see foaf: (see

18 Berendt: Knowledge and the Web, 1st semester 2016/2017, 18 Are there RDF data in a Website? E.g.

19 Berendt: Knowledge and the Web, 1st semester 2016/2017, 19 The LOD cloud (to click on details: Linking Open Data cloud diagram 2014, by Max Schmachtenberg, Christian Bizer, Anja Jentzsch & Richard Cyganiak.

20 Berendt: Knowledge and the Web, 1st semester 2016/2017, 20 The potential “a system that generates explanations for data mining patterns using background knowledge retrieved from Linked Data”

21 Berendt: Knowledge and the Web, 1st semester 2016/2017, 21

22 Berendt: Knowledge and the Web, 1st semester 2016/2017, 22 The potential (example of the use of traversing LOD)

23 Berendt: Knowledge and the Web, 1st semester 2016/2017, 23 The potential (contd.)... And of course our invited speakers!

24 Berendt: Knowledge and the Web, 1st semester 2016/2017, 24 BTW: Semantic non-interoperability has real consequences...

25 Berendt: Knowledge and the Web, 1st semester 2016/2017, A spatial example (as recently as 2006)

26 Berendt: Knowledge and the Web, 1st semester 2016/2017, 26 Agenda The Semantic Web: Motivation and overview Semantics, concepts and ontologies Very brief recap of XML (& why it’s not semantic) RDF and RDFS Linked (Open) Data (LOD)

27 Berendt: Knowledge and the Web, 1st semester 2016/2017, 27 What is „semantic“ anyway? Semantics is the study of meaning. It focuses on the relation between signifiers, like words, phrases, signs, and symbols, and what they stand for; their denotation. Linguistic semantics is the study of meaning that is used for understanding human expression through language. Other forms of semantics include the semantics of programming languages, formal logics, and semiotics. In computer science, the term semantics refers to the meaning of languages, as opposed to their form (syntax). In logic, formal semantics OR logical semantics,[1][2][3] is the study of the semantics, or interpretations, of formal and (idealizations of) natural languages usually trying to capture the pre-theoretic notion of entailment.

28 Berendt: Knowledge and the Web, 1st semester 2016/2017, 28 What is „semantic“ in the sense of the Semantic Web? To use web content, machines need to know what to do when they encounter it, which, in turn, requires the machine to know what the content means (that is, its semantics). The challenge of developing the semantic web is how to put this knowledge into the machine. The manner in which it is done is at the heart of the confusion about the semantic web. The goal of this article is to clear up some of this confusion. Uschold, „“Where Are the Semantics in the Semantic Web?”, AI Magazine 2003, 16/1614

29 Berendt: Knowledge and the Web, 1st semester 2016/2017, 29 Search for „FUEL PUMP“  why information about pistons may be relevant

30 Berendt: Knowledge and the Web, 1st semester 2016/2017, 30 Doesn‘t Google do this (without knowledge structures in the background)?

31 Berendt: Knowledge and the Web, 1st semester 2016/2017, 31

32 Berendt: Knowledge and the Web, 1st semester 2016/2017, 32 An overview of history, state of things, and possible futures LINKED DATA: WEB SCIENCE AND THE SEMANTIC WEB A Conversation with Tim Berners-Lee [ ] web-science-and-the-semantic-web

33 Berendt: Knowledge and the Web, 1st semester 2016/2017, 33 Texts on LOD applications Heath, T. & Bizer, C. (2011). Linked Data: Evolving the Web into a Global Data Space. Chapter 3.Linked Data: Evolving the Web into a Global Data Space. Wood et al. (2014). Linked Data: Structured Data on the Web. The Euclid Project Consortium (201x?) Euclid book, section 5.3 Using Linked Data Effectively. Gocebe et al. (2015). Bringing Agility into Linked Data Development: An Industrial Use Case in Logistics Domain. Proc. LDOW.

34 Berendt: Knowledge and the Web, 1st semester 2016/2017, 34 More on LOD n W3C Linking Open Data community project: cts/LinkingOpenData cts/LinkingOpenData n A nice slideset is available at bizer.ppt bizer.ppt n A book: Heath, T. & Bizer, Ch. (2011). Linked Data: Evolving the Web into a Global Data Space. Morgan & Claypool.

35 Berendt: Knowledge and the Web, 1st semester 2016/2017, 35 Used sources (unless cited on the slide itself) (From or based on): Costello, R.L. & Jacobs, D.B. (2003). A Two Minute Intro to XML. ocks.ppt ocks.ppt Unnamed (no date). RDF and XML tutorial. Dedalo:: Uschold, „“Where Are the Semantics in the Semantic Web?”, AI Magazine 2003, In various places (the texts with many hyperlinks in them): Wikipedia entries on FOAF, the Semantic Web, JSON, concept, semantics, versions 14 Oct Picture credits: see PPT „comments“ field

36 Berendt: Knowledge and the Web, 1st semester 2016/2017, 36 Further references, background reading; acknowledgements Specifications: RDF: OWL: OWL2: FOAF:

37 Berendt: Knowledge and the Web, 1st semester 2016/2017, 37 Outlook (next week) The Semantic Web: Motivation and overview Semantics, concepts and ontologies (contd.) Very brief recap of XML (& why it’s not semantic) RDF and RDFS Linked data, open data, Linked Open Data