International Semantic Web Conference 2008
Tutorial – Introduction to the Semantic Web

Sunday 26th October – Afternoon

“Semantic Interoperability” – Jerome Euzenat & Natasha Noy
Much of the promise of the Semantic Web stems from the claim that we will be able to query heterogeneous data sources. For this to work the ontologies from the data sources need to be ‘aligned’ and this is not simple. It can be partially automated, but requires human intervention both to identify missed matched and confirm correctness of automated matching. Once the ontologies are aligned a transformation between them can be automatically generated. The transformation may translate queries/triples, or simply create new assertions that make axioms in the data sources equivalent. Combining different techniques can help, though this then introduces the need to aggregate, filter and trim results. In tests precision/recall vary from under 50% to over 80% if ontologies are ‘relatively similar’. Best performers in Ontology Alignment Evaluation Initiative (OAEI) tests are Falcon and RiMOM.

“Semantic Web Services” – John Dominingue & David Martin
We start with an overview of Web Services today. They are syntactic, most integration tasks need to be carried out by developers and they can have problems scaling. The goal of Semantic Web Services is to “automate all aspects of application development through reuse”. The idea is that we can build clients that can analyse a query and choreograph/orchestrate the interaction with one or more web services to provide potential solutions. David and John describe OWL-S and WSMO respectively. They both provide mechanisms that extend the description of web services through added semantics to make the mediation between client and service more automatable. David describes Fujitsu’s Task Computing and John covers eMerge, a system developed to assist with emergency situations in Essex. They then describe the W3C recommendation for SAWSDL that allows traditional 3 extensibility elements for WSDL: modelReference, liftingSchemaMapping, loweringSchemaMapping.

“Linked Data – the Dark Side of the Semantic Web” – Jim Hendler
Darth Vader reared his head at the beginning of this session, but was quickly dispelled. Jim is talking about the unseen side of the Semantic Web, the ability to link data dynamically. An example he gives is the (largely theoretical) wine chooser application that downloads the menu for the restaurant you are eating at, prompts you to pick the dishes that you and your companions are choosing and based upon your (& their) preferences, the downloaded wine list and some online service that matches foods to wine characteristics, recommends what wine(s) to choose. I’m not entirely convinced – my heuristic of pick a colour and don’t choose any whose price makes you perspire seems to work fine. He also talked about deployed websites such as Twine, LiveJournal, Freebase and DBpedia and described the huge online RDF resource at the W3C SWEO Community Project LinkingOpenData. A brief discussion of Semantic Gridding/Seeded Tagging followed and the assertion that many of the larger commercial companies were entering the Web 3.0 arena in the belief that it is only a matter of time before it provides winners to join Google (Web 1.0) and Facebook (Web 2.0) Hall of Fame. This is exemplified by Microsoft’s recent acquisition of PowerSet earlier this year.

“Using the Semantic Web” – Mathieu d’Aquin
Mathieu was (if this is possible) even more excited than Jim. He had been hoping to demonstrate several application that make use of Semantic Web APIs, but the connectivity at the conference centre is pretty poor. Consequently we had to make do with static images, but he was still convincing. He is the developer of Watson, an online Semantic Web query service (http://watson.kmi.open.ac.uk) that enables you to quickly search all marked up data on the web to discover relevant resources. You can then issue SPARQL queries against the resource, or use some of the precanned API calls, such as subclass/superclass, and he showed how he quickly knocked up a search engine, Wahoo (derived from Yahoo), that used Watson to populate a sidebar with specialisations/generalisations of the search terms entered. There are other services out there too, such as OpenCalais SemanticProxy and Hakia. Also worth a look, apparently, is the Talis platform, that will actually store your data for you!