Finding Rahoon

Rahoon is a nondescript area of Galway, the third-largest city in the Republic of Ireland. Unsurprisingly, I had never heard about Rahoon before last week, when I moved there, to join Giovanni Tummarello’s team at DERI Galway.

Moving is stressful. But being an RDF geek, I not only have to drag physical stuff around, but I also have to update a few triples. For example, by joining DERI I got yet another URI:

That’s a new owl:sameAs for my FOAF file. I also have to update my foaf:based_near triple. Until now, my FOAF file stated:

<#cygri> foaf:based_near <> .

The obvious new value for this property would be But I want to be a bit more specific. That’s where this post’s title comes in. *What is the URI of Rahoon?*

The big datasets: Unfortunately, Wikipedia doesn’t have an article for Rahoon, hence it isn’t in DBpedia.

Then there’s Geonames, the most comprehensive source of geographical information on the Semantic Web. It has an entry for a nearby structure called Rahoon House, but not for the area itself.

The search engines: Next I tried all the Semantic Web search engines from the Linking Open Data project’s list.

Of the seven available services, only three produced any results. I was quite disappointed that the venerable Swoogle, one of the first large-scale Semantic Web indices, didn’t return any results at all.

SWSE (a DERI project) returned two hits, but neither of them was semantic (a web page mentioning Rahoon and a Bollywood-related RSS item).

Sindice (disclosure — it’s another DERI project, and I am now a team member) did much better, it found Geonames’ Rahoon House, and a bunch of loosely Rahoon-related things from DBpedia, but it didn’t turn up any URI for the Rahoon area itself.

Finally there is Falcons, a recently announced project developed at Nanjing’s Southeast University. Its results are similar to Sindice’s, except that it missed the Geonames entry.

In summary, only Falcons and Sindice found anything of interest, but neither struck gold.

Mint your own? At this point, I perhaps have to accept that the only existing relationship between RDF and Rahoon is the fact that Giovanni has been living here for a while, and that I’m not going to find a URI for the place.

The usual advice at this point is to mint a new URI for the thing in question. But I don’t want to go down this road, because I simply do not feel sufficiently competent in matters of Irish geography. What ”is” Rahoon, really? An administrative area? A geographical region? A postal code? A bus stop? I don’t know.

Based near a blank node: My solution is to ignore the widely accepted wisdom that RDF blank nodes are considered harmful. I will state that I’m living near something, and describe that something as good as I can:

foaf:based_near [
    a pos:Point;
    pos:lat "53.27702";
    pos:long "-9.09019";
    rdfs:label "125 Rosan Glas, Rahoon, Galway, Ireland";
    geo:parentFeature <>

The skeleton of this N3 fragment was easily created using my FOAF geolocator (which I recently extended with address search and N3 output — have a look at it if your FOAF file still lacks geolocation!). I added a label and a link to the next-largest Geonames feature (Galway), which I easily found with Sindice.

Rahoon is still without a URI, but I guess I should let it be for now and rather worry about applying for a social security number, registering for taxation, and so forth.

DERI! At any rate, I’m happy to be here and look forward to working with a great team on some very exciting projects.

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12 Responses to Finding Rahoon

  1. Simon Raboczi says:

    I completely agree with the bnode solution. Sometimes you just have to identify things by the naming properties they DO have! I think the bad rep that bnodes have is unfortunate. They’re not making knowledge representation harder; they’re just making hard representations possible.

  2. Simon: I agree to some extent, but blank nodes do make linking much harder. For example, it is really hard for someone else to state that they live in the same area as me.

    It is a trade-off. Minting a new URI has associated costs. Preventing others from linking into your data has associated costs. The decision has to be made on a case-to-case basis.

  3. IMO some things (eg. a rather ill-defined “area”) don’t have names, and it doesn’t make sense to give them one.

    If someone wants to say they live in the same area as you, it makes more sense to use GeoOnion or put down their coordinates and let processors decide what to do with that data.

  4. Brendan: The area in question might be ill-defined, but it certainly has a name, and the locals use it without any trouble. It’s just that no one has bothered to put that name on the Semantic Web yet.

    Knowing I live in Rahoon is immediately useful to people who know Galway. Knowing I live within 500m of 53.27702/9.09019 is useless unless you bring quite a bit of machinery, and that machinery is simply not available in today’s Semantic Web clients.

  5. John Breslin says:

    Welcome to DERI Richard, sorry I won’t meet you until next week.

    How about

    Talk soon!


  6. Why not just create an appropriate article in Wikipedia? I guess this would help some other people, too.

  7. Hi Richard

    If it’s not in geonames, just add it!
    There is a wiki interface in geonames just for that kind of situation.
    Juts made it for you :
    I guess “section of populated place” is the right type for Rahoon.
    If it’s not you can change it, and you can move the pin too, if it’s not in the right place. I put it close to Rahoon House, my best guess, but you will know better.

  8. Well, seems something got wrong in geonames data base works OK
    But is ‘unknown record’ … will investigate.

  9. John: Looking forward to meeting you next week. Keep the reports from Busan coming! The URI you gave is a nice web page about Rahoon, but not usable as an identifier for the locality (a web page is not a geographic place). I added a foaf:page link from my blank node to the page.

    Bernhard: You are right, but I don’t know much about the place and don’t want to clutter Wikipedia with unnecessary stubs.

    Bernard: Cool! I moved the place a few meters eastward to coincide with the location given in the Galway city map. Also assigned Galway County as the administrative area. Rahoon is, legally speaking, a “civil parish”.

  10. Peyman says:

    Why you dont invent your own URI? :) Anyway, I was in Rahoon for 10 months. It is far from DERI.

  11. Andy Mabbett says:

    Unfortunately, Wikipedia doesn’t have an article for Rahoon

    Isn’t the point of Wikipedia that you can create one?

  12. Andy Mabbett says:

    Isn’t the point of Wikipedia that you can create one?

Comments are closed.