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Semantic Web Systems Introduction Jacques Fleuriot School of Informatics 11 th January 2015
Semantic Web Systems
Introduction
Jacques Fleuriot
School of Informatics
11th January 2015
Semantic Web Systems: Introduction
The World Wide Web
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Semantic Web Systems: Introduction
Requirements of the WWW
l The internet – already there
l HTML programmers
l Core weight of interest
l Search engines
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Semantic Web Systems: Introduction
Why do we need the Semantic Web?
I have a dream for the Web [in which computers] become capable of analyzing all the data on the Web – the content, links, and transactions between people and computers. ...the day-to-day mechanisms of trade, bureaucracy and our daily lives will be handled by machines talking to machines.
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Tim Berners-Lee (1999) Weaving the Web
Semantic Web Systems: Introduction
Scenario What are you doing on Burns night?
⇒ Google “burns”
⇒ Wikipedia articles on Robert Burns
⇒ Amazon Listings of books by Burns
⇒ Google Maps to look at birthplace of Burns
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Semantic Web Systems: Introduction
Google query
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Semantic Web Systems: Introduction
Wikipedia article
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Semantic Web Systems: Introduction
Amazon
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Semantic Web Systems: Introduction
Google maps
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Semantic Web Systems: Introduction
Combining Information
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Semantic Web Systems: Introduction
Combining data from one source with a service from another
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Semantic Web Systems: Introduction
Web APIs l A large and growing number of web data sources
provide program-accessible interfaces (APIs)
l Website programmableweb.com currently lists over 14 000 (December 2015).
l Most popular APIs (November 2015):
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Semantic Web Systems: Introduction
Limitations of Web APIs l The interfaces are non-uniform – REST, RPC
(e.g. SOAP) and hybrid
l The results are returned in variety of formats –XML, JSON, Atom
l The data schemas tend to be provider-specific l Militates against the development of portable,
generic methods of accessing and using data
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Semantic Web Systems: Introduction
The Semantic Web l Invented by Tim Berners-Lee and others. W3C
driving organisation.
Web of machine-readable data
l What are the main aims of the SW? § Automated query-answering
§ Automated use of the data (reasoning, planning, acting, etc.)
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Semantic Web Systems: Introduction
WWW vs Semantic Web
l WWW is a web of documents
l SW is a web of data
l WWW documents are human readable
l SW data is machine readable (in theory at
least)
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Semantic Web Systems: Introduction
Why the Semantic Web?
I don’t think [the Semantic Web is] a very good name but we’re stuck with it now. The word semantics is used by different groups to mean different things ...I think we could have called it the Data Web. ...it connects all applications together or gives [people] access to data across the company ...
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Tim Berners-Lee (2007), Interview in Business Week
Semantic Web Systems: Introduction
Why the Semantic Web?
l Syntax / semantics distinction: long history in
philosophy of language, linguistics, formal logic
l Syntax concerned with arrangement of symbols
l Semantics concerned with the relation between
symbols strings and the world: what things
actually mean
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Semantic Web Systems: Introduction
What can the Semantic Web actually do? Query answering IBM’s Watson: beats human competitors at Jeopardy
but l It was specifically trained for this task (including looking at decades’ worth of past Jeopardy answers)
l It is sort of cheating (reaction times means it always gets first go!)
18 Extra info: API Provider at http://watson.kmi.open.ac.uk
Semantic Web Systems: Introduction
What can the Semantic Web actually do? Query answering Wolfram-alpha: does complex query-answering and solves mathematical problems
but l Hand-curated database – not the Semantic Web
l Hugely labour-intensive to develop and cannot take advantage of new knowledge
19 Extra info: API Provider at http://wolframalpha.com
Semantic Web Systems: Introduction
What can the Semantic Web actually do? Query answering Other systems:
l There has been considerable progress
l Current state-of-the-art is extremely useful
But l The general case is hard!
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Semantic Web Systems: Introduction
What can the Semantic Web actually do? Automated use of data l Works well in constrained circumstances:
§ For example: Google maps can automatically combine information about maps, speed limits, current road usage, etc. to get estimates of journey time
l Very hard in unconstrained circumstances: § Classic SW example of an automated travel agent
is still far from achievable
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Semantic Web Systems: Introduction
What are the requirements of the Semantic Web? l Large numbers of users to make their data:
§ available § in an appropriate machine-readable format
This is happening now: open government data (esp. in the UK and the US) and many other organisations and individuals
l Good query-answering systems
l The ability to automatically interpret and use data
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Semantic Web Systems: Introduction
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This course
Semantic Web Systems: Introduction
This course is l About:
§ The Semantic Web foundations, trends and future § Fundamental concepts
§ Principles
§ Tools and technologies
l Both theoretical understanding and practical experience § Lectures + Guest lectures
§ Practical lab § Exercises 24
Semantic Web Systems: Introduction
This course will cover:
l Fundamentals of knowledge representation: § Ontologies and databases
§ Formats: RDF, RDFS, DL and OWL
l Data querying l Linked Open Data (LOD)
l Services
l The aims and goals of the Semantic Web, and their plausibility
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Semantic Web Systems: Introduction
Textbooks
26 SWWO
Semantic Web Systems: Introduction
Coursework
l Each counts towards 30% of your final grade. l Start work on this as early as possible: it will help your
understanding of the course, as well as improve your work. l Deadlines are non-negotiable.
l TA: Paolo Pareti Marker: Can Cui 27
What Weight Submission Deadline Assignment 1 50% Monday 29th February, 4pm
Assignment 2 50% Friday 25th March, 4pm
Semantic Web Systems: Introduction
Finding out more l Recommended reading can be found on the course
website: http://www.inf.ed.ac.uk/teaching/courses/sws
l Useful pointers on the (old but useful) MASWS wiki.
l There is a lot of relevant literature online – try to explore it.
l Also a lot of informal discussion on Twitter, blogs, YouTube, etc.
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Semantic Web Systems: Introduction
Reading l Chapter 1 in SWWO.
l The Semantic Web by Tim Berners-Lee, James Hendler and Ora Lassila. Scientific American, May 2001.
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