Ontology Alignment (is not the SameAs but is CloselyRelatedTo) Reconciling Worldviews

For the next three days, I’ll be reporting from the 8th International Semantic Web Conference (ISWC), taking place near Washington DC. A lot of what’s going on here is very technical, so rather than repeat everything I’m hearing, I’m going to talk about the broader themes that I see emerging. After this conference, I may try to tie them together into one comprehensive post.

This is my first theme. It’s about ontology alignment but is nevertheless very interesting. Yes, actually, it really is.

An ontology is basically a taxonomy of concepts and categories and the relationships between them – it’s sort of like a network but includes heritability (if I specify properties about some group, like “dogs can bark,” then it carries down to things within that group, so we know that Shih Tzus can bark). Ontologies are pretty key to the Semantic Web because expressing relationships between concepts is essentially defining those concepts – I could turn philosopher and argue that the meaning of something can only be found in the way it relates to other things. Or I could not, and just argue that defining things in terms of their relationships is a really useful way to do it, especially if the point is to make machines understand those things and be able to reason about them. That’s why a large percentage of the people here are obsessed with building ontologies about certain things (like jet engines).

But ontologies are personal. What if I think of “Shih Tzu” as a sub-category of “pets” but you think it belongs under “dinner proteins?” Or how about if a liberal defines a homosexual relationship as a type of family and a conservative thinks it belongs under sexual perversion? There’s no way the world would ever be able to agree on one definitive ontology. Nor should it. The way we categorize things, the way we cut up and connect up everything in the world is key to who we are, how we think, and what we do. I – an atheist and cognitive psychology nerd – would go so far as to say that the human soul exists in our subjective, idiosyncratic ways of linking up information. So to impose a single ontology on the whole world – no matter how well thought out and exhaustive it is – would be tantamount to mind control or soul stealing.

To their credit, most semantic technologists I’ve talked to think this way also. That’s why they’re encouraging ontologies to be fruitful and multiply and represent as many worldviews as there are ontology-builders (though ideally there would be more than 15. (I’m joking, I’m sure there are over 22 people who can build ontologies)). But having a bunch of rivaling ontologies out there that define and categorize things in unique ways doesn’t sound like much of an organized system of data, right? That’s true, and that’s why a lot of other people are involved in aligning ontologies – matching up the instances of some concept that shows up in different ontologies.

But…they’re still not doing it that well. That’s something Pat Hayes brought up during his keynote this morning. His topic was “blogic,” or, the new form of logic (formal logic) that’s required for the web. One of his problems with using traditional logic for the web is that people are mapping instances between different ontologies using the relationship “SameAs” – even though the fact that they come from different ontologies means they’re clearly not the same as each other. People are usually aware of that, but there’s still not much they can do because there’s no “SortOfSameAs” or “SameAsInThisOneParticularWay” relationships in traditional logic that they can use instead.

Ontology alignment is still a Big Problem and it’s acknowledged as such by much of the Semantic Web community. If anyone knows of good solutions in the works, I’d love to hear about them or add to this post with some comments.


about Web 2.5

This blog is about how the current World Wide Web is becoming the web of the future. If you’re someone who uses the Internet (presumably you just did), then this blog is very much about your future. What’s great is, the future of the web is all about total, universal connectedness.

Some good reasons for reading this blog (or just learning about Web 3.0):


  • As an antidepressant: Most of the future (political, economic, environmental, Mad Men) looks bleak. But the future of technology looks sunnier every day. Visions of the next World Wide Web depict our lives as more organized, our scientific research more effective, and the information of the whole world better connected than it is today. Really, the tech people I talk to are some of the happiest and most idealistic around.
  • Out of interest: Personally, I love reading anything about Google, Twitter, Wikipedia, or Craigslist because most of their news is directly relevant to me. I’m even more interested in what future web phenomenons will look like, but because the people behind them tend to be so very smart – and a little disconnected from the rest of us – they often don’t write for those of us with non-technical backgrounds. On this blog, I’ll be doing the work of filtering and translating the best news and information about our collective journey toward Web 3.0.
  • To be a pioneer: The beauty of the World Wide Web (it is beautiful) is that it is the great democratizer. No one’s URL – the New York Times‘ or mine – is easier to reach than any others’ and anyone with a really good idea can become the next Mark Zuckerberg or Craig Newmark. The next generation of the web is almost here and you can encourage it, shape it, or profit from it, but only if you’re armed with knowledge about what’s going on.

So what’s the big idea?

The Web is just a social teenager…

The World Wide Web is still maturing. In the nineteen short years of its life, the WWW has grown from a small network of computers at a physics lab in Geneva – and from the brain of an idealistic English scientist there – to emerge as a new non-national, non-physical space that is open to anyone and contains the intellectual wealth of the entire world. We’re still grasping the implications of such a network. It’s only recently graduated to Web 2.0 – the social web – during which user participation exploded everywhere into editable sites like Wikipedia, countless web applications built on open source software and instant info-sharing sites like Twitter, Digg, and Reddit. Web 2.0 is the realization of the wisdom of the crowds: that the many are smarter than the few. The success of the social web showed us how much people can achieve when everyone everywhere can collaborate.

…and hasn’t realized yet how to put together everything it knows.

But while people have figured out how to work together effectively on the Internet, despite differences in language or nationality, computers are still way behind at sharing information. Why can’t your emailed RSVP to a party automatically show up as an event on your calendar and why can’t search engines figure out what you’re asking and just give you the right answer? Because the web is still set up for people to communicate, but not for machines. All those applications that let people access information also hide it from our computers in layers of irregular formatting and code that tells them how to display data, but not what it means.

What’s going to happen?

That’s where Web 3.0 comes in. Often referred to as the “Semantic Web” – a term coined by Tim Berners-Lee, that same English scientist who invented the web – the next thing to revolutionize our online world is the beginning of smart computer-to-computer communication. Instead of a web of human-readable documents, Web 3.0 will be a web of data, where every piece of information is semantically (meaningfully) linked to every other one. The WWW will become a giant computer-searchable database where we won’t waste our time on lengthy searches and transferring data between applications, because our computers will already understand the relationships between pieces of data on the web.

So what’s Web 2.5?

Well, we’re not quite ready for Web 3.0. For a complete Semantic Web, every piece of data would have to be marked-up with tags that tell computers what it’s about and what its relationship is to everything else. That would basically mean rewriting everything that’s on the web (using a semantics-based language such as OWL). But until then, the tech world is coming up with tools to interpret what we’ve got – an unstructured mass of information – to approach the ideals of the Semantic Web – a smarter, better-linked web of data. For example, work in natural language processing and question-answering (i.e. “What would be better for my six-year-old’s headache, Tylenol or aspirin?”), social graphing (a total mapping of how everyone is related to everyone else, or, the ultimate social network), or efforts to free your data from applications are all mini-steps toward computer understanding of the relationships between information. And they’re all part of what I’m calling Web 2.5: the transition from a web of tangled words to a web of interwoven meaning. Along the way, the developing technology will be spawning some very smart new sites and applications – like HealthBase, Dapper and Wolfram Alpha – but ultimately it’s headed toward the creation of a newly-connected world, whose full significance we can’t yet predict.