Semantic Web Company

Bernardo Cuenca Grau, Ian Horrocks, Boris Motik, Bijan Parsia, Peter Patel-Schneider, and Ulrike Sattler. OWL 2: The next step for OWL. J. of Web Semantics, 2008.
Download (PDF, 248 KB)

Abstract:
Since achieving W3C recommendation status in 2004, the Web Ontology Language (OWL) has been successfully applied to many problems in computer science. Practical experience with OWL has been quite positive in general; however, it has also revealed room for improvement in several areas. We systematically analyze the identified short-comings of OWL, such as expressivity issues, problems with its syntaxes, and deficiencies in the definition of OWL species. Furthermore, we present an overview of OWL 2—an extension to and revision of OWL that is currently being developed within the W3C OWL Working Group. Many aspects of OWL have been thoroughly reengineered in OWL 2, thus producing a robust platform for future development of the language.

My colleague Tassilo Pellegrini recently did an interview with Bo Hu, a researcher and former fellow at the Intelligence, Agent, Multimedia Group (IAM), University of Southampton: At present, Bo is working at the SAP Research Center CEC Belfast where his research focuses on the application of Semantic Web and Web 2.0 technologies in e-learning and e-healthcare. In the interview, he talks about the potential of Semantic Web and intelligent agent technologies in medicine and life sciences, which he sees as a discipline particularly suited for semantic technologies as “many sub-domains of medicine are subject to controlled nomenclatures providing solid ground upon which semantically enriched applications can be built.” About the potential of intelligent agents:

[...] in distributed environments, it is difficult to exploit the available data from different sources, especially data that is normally projected onto the body of a patient to reach diagnostic and prognostic decisions. Many of the available data are interrelated, calling for paradigms that facilitate knowledge discovery by intelligently integrating data sources.

An agent-based framework is particularly useful in this case where individual agents are equipped with “memory” and “reasoning/thinking” capabilities to constantly acquire new knowledge and solve allocated tasks. Communication among agents, prescribed by a common vocabulary/ontology, ensures the entire community works towards a common goal.

On the other hand, frameworks with agents encapsulating special functions deliver better customised and personalised healthcare. As a result, we will be witnessing more patient power and better adherence to treatment regimens.

Read the whole interview on the SWC website.

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So what’s been happening on the blogosphere after John Giannandrea’s keynote at ISWC and the revelation that Freebase now produces Linked Data from an RDF service…

Tetherless World sums up the Freebase facts (e.g. 156,000,000 assertions made; 1370 published types; 75 domains; graph model, identity, web based) and further points out that ontology creation “is a social process, and both freebase and semantic wiki are tools that enable users to create ontological vocabulary without worrying too much on building a comprehensive ontology.”

Inkdroid notes that the RDF service release “is important news because Freebase is an active community of content creators, creating rich data-centric descriptions with a wiki style interface, fancy data loaders, and useful machine APIs.” This is followed up by a quick and handy tutorial how you can get machine readable data back from freebase using a URI with Freebase. Conclusion:

So why is this important? Because following your nose in HTML is what enabled companies like Lycos, AltaVista, Yahoo and Google to be born. It allowed for agents to be able to crawl the web of documents and build indexes of the data to allow people to find what they want (hopefully). Being able to link data in this way allows us to harvest data assets across organizational boundaries and merge them together. It’s early days still, but seeing an organization like Freebase get it is pretty exciting.

Yves Raimond was the first to wonder on the public W3C LOD mailinglist: “now, to see whether it links to other datasets ” – the idea of having linked data without the linkage would indeed seem like love’s labour lost. Semantic Focus / James Simmons seconds: “One downside is the data doesn’t appear to link to external resources, in a sense walling itself in. It should be trivial to link the topics that came from Wikipedia back to Wikipedia as well as DBpedia (which would be killer, by the way).” This is followed up a later post, where James expresses concerns regarding the relationship DBpedia / Freebase: “Freebase may see a drop in userbase growth and participation if it becomes a mirror of DBpedia (or vice-versa) and the popularity once garnered by one project may shift towards the other, or away entirely.”

More News / Andrew Newman puts the Freebase RDF service release in context with Cathrin Weiss’ “250 million triples on your iphone” submission, iMoCo, to the Billion triples challenges, also DBpedia and Semaplorer, developed at the University of Koblenz:

DBPedia stood out because it was the only one that allowed you to write data to the Semantic Web rather than just read the carefully prepared triples. For a similar reason I though SemaPlorer was good because they tried to do more than just the standard triples but went that extra bit further by making it more generic like integrating flickr. But they were all excellent, all of them showing what you get with a billion or more triples and inferencing.

That combined with the guys at Freebase making all of their data available as RDF and it was a big day for the Semantic Web.

ARQtick / AndyS plays a bit with the Blade Runner example cited by Freebase, e.g. takes a look at the graph, looks for interesting properties and extracts author names

N.B. If you want to follow ARQtick’s example: use the Linked Data browser plugin Tabulator or go to the Marbles site to view the RDF – without a data browser you’ll be redirected to the HTML page. You will also need it to make sense of rdf.freebase.com.

Just two memos: There is a talk tonight with Thomas Länger from the Viennese quantum encryption project (BBC article about the project), co-organized by quintessenz (an organisation devoted to civil rights in the information age) and Transforming Freedom (who are dedicated to documenting the discourse of the battle zones of digital culture; I volunteer for them). ORF wrote a German article about it, with information about the venue and start time. The key issue quintessenz want to raise with this talk is: Who is going to benefit? Will “unbrekable” quantum encryption become available to citizens, too? Quantum encryption cartridges for your PC, anyone?

Secondly: I published an “inaugural interview” Marion Fugléwicz-Bren did with two of my colleagues, Matthias Samwald and Thomas Schandl (not so inaugural for the former, as he already joined SWC in January). I’d like to extract this quote by W3C member Samwald regarding privacy on the (corporation owned) social web and the future (user-managed) social semantic web:

I also think that Semantic Web technologies will receive a lot of media attention when the first big, public breach in security / privacy happens in one of the websites that currently dominate the whole world wide web. At the moment, we all are uploading most of our private and business lives to web sites such as Google, Facebook, Flickr and others. It is just a matter of time until a big scandal happens, be it the companies themselves that misuse the vast amounts of data they have, or be it a government agency in an overzealous effort of crime prevention.

When this will happen, people will re-evaluate the trend towards massive centralisation on the web, and will search for opportunities to make the same feeling of being ‘in the network’ happen in a distributed environment, without selling ones soul to a multinational corporation. Then we will find that such an opportunity already exists — the Semantic Web.

Read the whole interview here.

The Web of Data Practitioners Days concluded with the session on Multimedia in the Web of Data, the first part of which was led by Ansgar Scherp (University of Koblenz-Landau, Germany).

Multimedia content, as Ansgar pointed out, is hardly annotated, badly organized, and hardly ever looked at again – just think of the 300 something pics you might take on an average week-end getaway, and which you never touch again. Annotating multimedia content requires a lot of work and dedication – but most of the time, these pictures eventually dissappear in the “digital shoe box” that is your photo management software.

The most obvious remedy is to annotate content as early as possible, ideally when creating the content, ideally already on your portable camera (formerly known as: mobile phone:) Ansgar suggested to provide incentives for people to encourage picture annotation – professionals could for instance receive a higher financial reward if the deliver already annotated pictures. And of course there are ‘Games with a purpose’ such as Google Image Labeler, where players tag images in pairs, with and against each other, and are rewarded with the entertainment factor of the game.

The slide below shows what has happened (or will happen) to the process of creating photo books in the digital age and the age of mashups:

After all, this is the age of the social semantic web, so why not try and (re-)use the content, structure and contexts that other users have already created on the web? Content augmentation, for the scope that Ansgar is concerned with, consists in the reuse of content and structures (e.g. from sources such as Flickr and Wikipedia, Geonames) made possible through the definition of rules, e.g.:

• If there are two or less pictures on a page*
• then automatically augment the page with additional photos using location information.

* Page here means a page in the album you are currently working on – you probably took a picture of yourself and your friend in Paris, and even though you went to the Centre Pompidou, you forgot to actually take a pic of the building itself – well, let the web be your library!

So the goal is clear: develop a procedure for applying automatic content augmentation in the creation of good photo books.

But what makes a ‘good’ photo book anyway? Here are some of the results of a structural analysis of real, human-created photobooks conducted at CeWe Color:

• % of photos with faces: 36%
• Number of album pages: 16.96
• Photos per page: 6.69
• Text fields per page: 1.45
• % of pages with text: 87%

There are many rules that can be established from the structural analysis, which can be applied in turn in the creation of photoboooks, e.g. rules like this one,

• If the text located in the upper third of a page
• if the font size is equal or larger that 16 points
• if the number of words is less than 10
• if there is no caption on the page that has a bigger font size
• then this page is the title

Ansgar recommended xSmart, which he described as a “context-driven authoring tool for page-based multimedia presentations.”

Ansgar’s presentation was followed by two more: one by Yves Raimond on Interlinking Music on the Web of Data, and one on Interlinking Multimedia – in spite of better intentions, I did not manage to cover these two in detail, but at least I gathered the links to relevant resources from all three sessions… (more…)

This morning’s first session was dedicated to Using the Web of Data, or, as Alan Dix put it: “In the end, it’s not about data – it’s about use!” Alan and Richard Cyganiak were the keynoters for this session.

Alan Dix is a Professor at the Computing Department of Lancaster University, and author (with Janet Finlay, Gregory Abowd, and Russel Beale) of Human-Computer Interaction.

To start with, Alan pointed to the two sides of achieving the web of data: Firstly generating the web of data (a billion triples, as mighty as this may sound, is actually tiny, says Alan) and then, secondly, accessing the web of data.

With regard to generating the Web of Data, Alan distinguished between top down and bottom up approaches, counting to the former the creation of the web of data from legacy sources (i.e. where you take existing data and semantically lift them, e.g. from structured data) or web scraping such as DBpedia’s extraction of data from Wikipedia.

N.B.: This notion of ‘top-down’ does not imply a hierarchical relationship, but rather means that there is already a plan for what is going to be put on the web of data (e.g. ‘all semi-structured information on Wikipedia’ or ‘dataset XY from project Z’). The bottom-up idea here implies that data is added as the result of an action, or interaction, as the user/s go, e.g. relationships are created as the user expands his or her social network. For instance on Amazon, user interaction is used to generate semantics: People do not tell Amazon what they like, they simply buy it.

Having relationships of course does not imply yet that these relationships are part of the Semantic Web. Or, as Alan put it, “why should I be RDFizing my online presence if none of my friends are?”

Please take a look at the PDF of the Alan’s slides (2,4 MB) – what I cannot reproduce here is a chart he developed, which was very useful for describing current scenarios on the web and which posed a twofold question:

Does a website/platform have the web of data implemented? YES/NO
Is the web of data on ta website/platform apparent to the user? YES/NO

The possible combinations (YES/YES, YES/NO, NO/YES, NO/NO) provide a good heuristic tool for describing what is currently available, with and without the Semantic Web. Take, for instance, the shiny interface of Talis’ Project Cenote: Cenote’s vision is to “make library data visible in many contexts, inside and outside of the library, making the data much more accessible and visible to a wider audience – benefiting current and potential users of library services wherever they are.” On Cenote, the user doesn’t see that it’s got the Web of Dat in it – it is actually implemented, but not in a way that is apparent to the user.

On the other end of the spectrum, you have a platform like Facebook: Alan referred to Facebook as “the user’s own web of data”, i.e. web of relationships: The user is aware of these relationships (they actually shape his interaction and communication with the site), and the (numerous!) apps on Facebook continually add relationships, but, regrettably, insulated from one another and not using RDF (and don’t you try to take data out of Facebook!).

Two examples of public data that Alan cited and that grow as people/institutions add data do them are Freebase (the “open database of the world’s information” – see previous posts on this blog about Freebase) and Swivel. Swivel allows people, institutions, anyone to upload and explore data, also featuring official data sources such as (links go to their Swivel pages): New York Federal Reserve Bank, UNESCO Institute for Statistics, DukeResearch or EUROSTAT. According to Alan, there is already more data on Swivel now than in the whole Linked Data cloud.

Alan also mentioned the Social Graph API – o yesterday evening Luca Hammer (one of the web 2.0 people who had joined the Open Hacking Session) introduced me to the Wordpress Plugin “Meet your commenters” – Meet you commenters uses Social Graph to find social relations on the web, and adds these data to the commenter profiles it creates in Wordpress.

Image via WikipediaOn a different note: I took sometime today to explore Alan’s homepage and found the cute Christmas Cracker’s application which was first developed in 1999 and which is now also available on Facebook. As trivial as it may sound at first – sending virtual Christmas Crackers (with more than 5000 possible combinations!) is a good showcase for developing Human Interaction Scenarios, and a number of papers have been written about the application. Here is the casestudy which Alan recommends to begin with: Designing experience – virtual Christmas Crackers.

The abstract and a list of links to all websites and demos Alan discussed can be found here. Full reference: A. Dix and R. Cyganiak (2008). Using the Web of Data. Keynote at WOD-PD 2008 | Web of Data Practitioners Days, Vienna, Austria – Oct 22-23, 2008. http://www.hcibook.com/alan/papers/WOD-PD-2008/

Even if you have not met Richard Cyganiak in person, you have certainly come across one of his creations: The Linked Data Cloud. Richard is a research assistant at DERI Galway. In his demo, he gave us the opportunity to gain hands on experience, introducing a tool he dubbed Snorql, which is basically an easier to use version of a SPARQL-endpoint, as it already has the required prefixes ‘pre-installed’:

Using the Snorql interface, we could explore the dataset we had created collaboratively during Keith Alexander and Yves Raimond’s session. Writing SPARQL queries manually can be a challenge, but is next to impossible if you (like me) don’t know the syntax. But today we could just copy and paste all the queries from a website Richard had put up prior to his session – thanks a lot for the excellent preparation and demonstration!

Richard also showed a couple of RDF browsers in action, e.g. the Tabulator Plugin (“a Firefox extension which allows Firefox to handle data as well as documents”), or the Marbles Linked Data browser which is running right on beckr.org/marbles; enter, for instance http://api.talis.com/stores/wod-pd-sandbox/items/People/JanaHerwig (learn more about Marbles here).

Thank you, Alan and Richard – the combination of talk and demo was indeed a perfect intro towards using the Web of Data.

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The third session at WOD-PD was dedicated to “Bringing (Legacy) Data on the Web“, and led by Sören Auer (University of Leipzig, Germany) and Orri Erling (OpenLink Software) .

Sören Auer described the difference between the Web 1.0, 2.0 and 3.0 as follows: On the Web 1.0, you had many websites that provided unstructured, mainly textual content. On the Web 2.0, you have a few large websites that are specialised on specific content types. And, finally, on the Web 3.0, there are many websites which contain, and are able to semantically syndicate, arbitrarily structured content.

So why would we need another web? What you cannot do with the current web is finding answers to seemingly complex, yet in reality pretty mundane question such as: Where in Leipzig do I find an apartment that is close to bilingual, German-French child care facilities? Are there any ERP service providers which have offices in Vienna and Berlin? Who are the researchers in South-East Asia currently working on database related topics?

Sören further discussed three of the present means of bringing relation data to the web: Triplify (a web application plugin that exposes data from relational databases in RDF), D2RQ (a declarative language to describe mappings between relational database schemata and OWL/RDFS ontologies, developed at Free University Berlin), and Virtuoso Universal Server (a middleware and database engine hybrid delivering for instance data integration for SQL, RDF, XML, Web Services). With respect to Triplify, Sören – who is Triplify’s founder and main developer at AKSW Uni Leipzig – showed and discussed the configuration for Wordpress 2.1., which can be found here (click here for more configurations, e.g. for Joomla, OpenConf and Drupal). The next aim for Triplify is to become an integral part in enduser web app distibutions.

And important question raised by Sören was: How do next generation search engines know that something has changed on the web of data? He suggested three approaches:

1. Always try to crawl everything (this may sound silly – but that’s actually what is happening on the current web)
2. Ping a central update notification service – e.g. PingTheSemanticWeb.com – which works as a showcase, but will probably not scale if the data web gets really deployed.
3. Each linked data endpoint publishes an update log – e.g. with Triplify, as a special folder inside the Triplify namespace, e.g. http://example.com/Triplify/update

Also discussed by Sören and worth checking out is Reuters’ Semantic proxy – the demo went live in late September.

Orri Erling, as the lead developer of the Virtuoso Team, addressed the issue of mapping relational databases to RDF with OpenLink Virtuoso. In his talk, he addressed the pros and cons of RDF data warehouse:

Pros

• Even query performance across all data
• Possibility of forward-chaining inference
• Some SPARQL features may be better supported, e.g. Unspecified predicates

Cons

• Keeping data up-to-date
• Complex set up, needs dedicated servers: you don’t build them on a whim

What Virtuoso delivers is mapping of SPARQL to SQL against any existing schema (whether stored in Virtuoso or elsewhere); a physical quad-store (quad as in quadruple; not as in quad-bike ; and Federated/local Relational Data Base Management Systems (RDBMS).

A more detailed discussion of the requirements for Relational-to-RDF Mapping is available on Orri’s blog, where he discusses it in the light of his own experience. A power point presentation of a previous talk he gave to the W3C RDB2RDF Incubator Group can be downloaded here: Mapping Relational Databases to RDF with OpenLink Virtuoso (PPT, 115KB). His summary of the group discussions around the same topic, Requirements for Relational to RDF Mapping, can be found here.

Orri also showed the Virtuoso billion triples demo which, according to the corresponding blogpost, “is being worked on at the time of submission and may be shown online by appointment.” The demo was a submission to the Billion Triples Challenge.

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The next session at WOD-PD was given by Leo Sauermann (German Research Center for Artificial Intelligence DFKI, Germany), and Brian Davis (DERI Galway, Ireland). Leo introduced the idea of the Semantic Desktop, and more specifically, the Nepomuk Social Semantic Desktop. There’s good article about Nepomuk on Linux.com, written by Bruce Byfield on August 26, 2008, from which I quote the following, enlightening passages:

Ansgar Bernardi, deputy head of the Knowledge Management Department at Deutsches Forschungszentrum für Künstliche Intelligenz (DFKI, or the German Research Center for Artificial Intelligence) and Nepomuk’s coordinator, explains, “The basic problem that we all face nowadays is how to handle vast amounts of information at a sensible rate.” [...] “The point is, you have a vast amount of information on your desktop, hidden in files, hidden in emails, hidden in the names and structures of your folders. Nepomuk gives a standard way to handle such information.”

At a high level of generalization, Nepomuk has three main aspects, according to Bernardi. First, there is a standard framework for annotating pieces of information so that connections can be made between them. Second, there are ontologies, the sets of “documented shared understanding” or common concepts that can be defined for particular types of information, such as bio-science or computer desktop use. Finally, there are the tools for making or using the annotations and ontologies, what Bernardi calls the “workspaces that connect to other workspaces and help you in your day to day activities of collecting information, structuring it, making sense of it, and creating new information and communicating it.”

Leo has provided the relevant download links for those who “want to get their hands dirty” with Nepomuk (as he put it) on his blog. Leo Sauermann and Ansgar Bernardi also contributed an article about the Semantic Desktop to the recently published Social Semantic Web volume – a preview of the article is available here (in German – I’m sorry!).

Brian Davis‘ part of the talk focused on Lifting and Human Language Technology (HLT) for the Semantic Desktop – Semantic Lifting means to capture semantics and translate them into ontologies. Human language technology (HLT), in its broadest sense, can be described as computational methods for processing and manipulating language (for instance text analysis).

One of the goals of the Semantic Desktop is speech act detection for email – speech act here as defined by John Searle. At its most basic definition, a speech act is simply an utterance, but is also often understood more specifically as an illocutionary act (which is a term introduced by John L. Austin in How to do things with words), or a ‘performative utterance’, meaning that by saying something, one actually does something. For instance, the sentence “Please have the document ready for Workshop 1.” contains an instruction: It informs the reader about the requirements for a particular event, and asks him or her to meet these requirements.

Brian also introduced Roundtrip Ontology Authoring (ROA), which is a process that allows non-expert users to author or amend an ontology by using simple, easy to learn, controlled natural language. The process is a combination of Controlled Language for Information Extraction (CLIE) and Text Generation which is developed on top of GATE. ROA is documented on the the Nepomuk website; for further information about CLIE, read this article by Valentin Tablan, Tamara Polajnar, Hamish Cunningham and Kalina Bontcheva: User-friendly ontology authoring using a controlled language (PDF, 64 KB).

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Good morning from Vienna:) The Web of Data Practitioners Days really kicked off with a bang today – with Michael Hausenblas doing a strip! Only to expose the Semantic Web t-shirt he wore underneath his smart suit and tie, of course, but he really got the attention of attendees at 9:15 in the morning:)

First session – Web of Data 101 by Yves Raimond and Keith Alexander – explained the implications of the move from a Web of Documents to a Web of Data: With the Semantic Web architecture, data can be made explicit on the web. Data here means not only data contained in documents, but data describing persons, cities, bands, events, finally arriving at the “Web of Things” (see also this presentation by Dave Raggett, W3C, – PDF 2,7 MB). The Web of Data wouldn’t be a Web if the data weren’t interlinked – here is an overview of the principles of Linked Data:

• always use URIs as names for things
• more specifically, use HTTP URIs so that people can look up those names on the web
• when someone looks up an URI, provide useful RDF information (RDF is the data model used for data on the web of data)
• include RDF statements that link to other URI (otherwise it wouldn’t be a web).

Please also watch out for what is already happening and is going to happen in the future on www.bbc.co.uk/music/beta. This beta site is powered by MusicBrainz, the open content music database that is also part of the Linked Data cloud. Yves is collaborating with the BBC in the Programmes ontology project, the aim of which is to provide a simple vocabulary for describing programmes.

Yves’ intro was followed by a Turtle hacking session led by Keith Alexander. Turtle is a serialisation format for RDF, i.e. a format in which you can write RDF statements. The Turtle session is documented here on Keith’s Talis website. Even though I copied and pasted most of the code, I didn’t manage to produce a piece of valid code in N3 right away (i.e. not valid according to this validator). It only worked after I had removed the statements about who I know or what I am interested in – without these connections, what remains is a bit boring, I guess. But this looks like I managed to post at least something to the test store!

EDIT: Problem was that I had terminated the statements to soon, with a dot where a semicolon should have been; the demo didn’t allow me to overwrite the first post to the store, but here is my FOAF self-description in Turtle:

@prefix foaf:<http://xmlns.com/foaf/0.1/> .
@prefix owl:<http://www.w3.org/2002/07/owl#> .
@prefix people:<http://api.talis.com/stores/wod-pd-sandbox/items/People/> .

people:JanaHerwig a foaf:Person ;
foaf:name “Jana Herwig” ;
foaf:nick “digiom” ;
foaf:homepage <http://digiom.wordpress.com> ;
owl:sameAs <http://dbtune.org/last-fm/jezobeljones> ;
foaf:knows people:MichaelHausenblas, people:YvesRaimond, people:WolfgangHalb ;
foaf:topic_interest <http://dbpedia.org/resource/Semantic_Web>, <http://dbpedia.org/resource/Web>, <http://dbpedia.org/resource/Popular_Culture>, <http://dbpedia.org/resource/Lolcat>.

Achieved with zero Semantic coding skills – the Web of Data cannot be so hard to achieve:)

EDIT: Did do the update, too – just posted my first SPARQL query to this endpoint. Are the results going to be preserved in this link? Here is the query “by foot”:

PREFIX rdf: <http://www.w3.org/1999/02/22-rdf-syntax-ns#>
PREFIX rdfs: <http://www.w3.org/2000/01/rdf-schema#>
PREFIX people: <http://api.talis.com/stores/wod-pd-sandbox/items/People/>
DESCRIBE people:JanaHerwig

Publication recommendation: Alexandre Passant, Tuukka Hastrup, Uldis Bojars, John Breslin: Microblogging: A Semantic Web and Distributed Approach. 4th Workshop on Scripting for the Semantic Web. June 2, 2008, Tenerife, Spain. 12 pages, download link.