Sig.ma is a pretty advanced application implemented on top of Sindice which gives a very visual and interactive access to the “Web of Data” as a whole.  Best thing to do, really, is watch the screencast.

Sig.ma – Live views on the Web of Data from Sindice Team on Vimeo.

While the demo is probably.. agreably cool there is more to talk about.

While Sig.ma is by no mean the first data aggregator for the Semantic Web, its contribution is to show that the sum is really bigger than the single parts and exciting possibilities lie in a holistic approach for automatic semistructured data discovery and consolidation.

In Sig.ma, elements such as large scale semantic web indexing, logic reasoning, data aggregation heuristics, pragmatic ontology alignments and, last but not least, user interaction and refinement, all play together to provide entity descriptions which become live, embeddable data mash ups.

An interesting example:

when we first saw the B&W pictures (e.g. see the demo ) pop up automatically the first time we ran Sigma we were really excited: that DERI data had been there forever yet never meaningfully used or integrated.. let alone automatically! That DERI RDF file does no reuse the right URI for people , doesn’t use Inverse Functional Properties such as “emails”, and  uses only one of many ways to say “author”.

But here it was! That file was there, discovered automatically and  contributing marvelously to the mashup providing information about papers,  (including technical reports that would not be listed otherwise) an extra picture, the phone number, a confirmation of the personal homepage, research projects and more.

Note: this doesn’t mean that the DERI file is bad at all actually. It’s simply not unrealistically great, in other words it was created with a realistic effort, the same that we can expect from any data publisher.

There was no way to get that very useful data with classic  Semantic Web inference and rule consolidation alone. All it took was instead the mix of semantic web practices and tricks with pragmatic and elements of soft computing (quite basic indeed).

In our opinion it all makes sense and inspires the following thoughts:

1. A little semantic might in fact go a long way:  no way there could be something comparable to Sig.ma had we not had a large core of semantically structured data (the Web of Data itself). Publish way more please!  Be this in whatever format can be consolidated to RDF.

2. … it goes in fact even more a long way when the user is involved, and can with pragmatic actions (e.g. “reject” or “approve”) to  steer and validate the results.

3. For data publishers: just like on the HTML web you can simply care only about your site.  If you don’t reuse other people URIs or you don’t put “sameAs” links or you don’t really use the ontology everyone else is using then..  it can work all the same most likely and for most applications!

4. .. but overdescribe
Be verbose with your semantic descriptions,  more than what you would be for a human. A well described entity will be the best possible “entity” identifier that one could think. It will automatically generate invisible but robust links to others entity descriptions. So dont just write name = fooguy, make sure you expose all you have (and are willing to share) and let aggregation engines use this data to at least do the best consolidation possible.  Good descriptions will also make you show more often in semantic aggregations, foster new applications and make people more likely to integrate with you.

5. For data consumers: We are working for you really and willing to do the hard work.

This is again very similar to the HTML world. How difficult is to make sense of all the broken HTML out there? Very! How many people have to do it really? just a few, the browser makers.  Others can reuse their efforts and concentrate on other aspects. Sig.ma and Sindice are engines that do the hard part for you as a Web of Data developer.  We provide open services and open source components (heck, at the end of the week we’re even releasing our index open source , next the reasoning engine).  If there is interest and market others will come and there will be more choices.

Source: Sig.ma