For the third time, I'm attending the XInnovations (formerly known as XML-Days) 2008 in Berlin. Although I was often rather dissapointed about the quality of the conference program (you might refer to my previous posts about XML-Tage Berlin here), I decided to give it another try (simply because I can reach Humboldt University in Berlin with local public transportation in about 45 minutes). Also this time, there seemes to be some emphasis on semantic web technology (at least considering the program, there are Semantic Wikis in the Corporate Wiki track and anoteher Corporate Semantic Web Workshop, not to forget the Semantic Web topic in the PhD-Forum).
I started the first day of the coference with participating the Coprporate Wiki Infotag. Denny Vrandecic is talking about the "Semantic Media Wiki" from AIFB Karlsruhe. Denny is starting his talk with some historical facts about WIkipedia. Interesting thing to mention, according to a study from Aaron Swartz, only 2% of all Wikipedia users (it come up to 1.400 people) are primarily responsible for all article changes. This contradicts the commonly assumed opinion that wikipedia is written by millions of users. Then he was introducing the semantic web in general, by stating that the semantic web is nothing but things (nodes, concepts) being connected by certain relationships, forming graphlike structures that can again be related to each other. According to his definition, a semantic wiki is nothing but graphs being created from wiki data.
The next talk I'm attending is in the Ph.D workshop. Olaf Hartig is talking about 'Trustworthiness of Data on the Web'. With the Semantic Web more and more software agents are taking decisions based on (RDF-based) data on the web. But how can we trust those data? Olaf is developing an RDF trust model as a basis for trust assesment and trust-aware data acces. He suggests a scale from [1-;1], where -1 represents 'absolute distrust' and +1 'absolute trust' for a statement. Now, all relationships in an RDF-graph can be weighted with according trust values ranging from [-1] to [+1]. Trust into a set of statements can be expressed with aggregated trust functions ranging from a cautious (conservative) minimum to a slightly optimistic median. The formal trust vocabulary can be found here. Next, criteria for trust assessment are collected and three different trust assessment strategies are defined: user-based (ask the user on his/her opinion about the trustworthiness), provenance-based (taking into account the trustworthiness of the referring users), and opinion-based (recommendations by other users according to their own trustworthiness).
The afternoon session started with Nils Barnickel from Fraunhofer IOCS with a talk on 'Semantic Mediation between Loosely-Coupled Information Models in Service Oriented Architectures'. Semantic descriptions of Web Services are supposed to enable data and service interoperability. One problem being addresses ist the lack of efficient ontology mapping options in current existing onlology languages (although OWL does have a differentFrom or sameAs operator, complex mappings deploying concepts with totally different subgraphs or 1:n, n:m mappings are missing).
Ok, now it's definitely time for a coffee break. after that, I will be joining the 'World Cafe' session, where I will participate in the discussions instead of writing blog.
[to be continued tomorrow, XInnovations Day 02, Corporate Semantic Web Workshop]