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Friday, June 02, 2006

Modelling of Condominiums

A condominium in this case being a geographical area of which two of more sovereignties agree to share dominium, but that title ought to do wonders for my statistics.

Anyway, I was thinking about the mapping between cities and zip codes today, which is a many-to-many relationship, and the thought popped into my head, "I wonder if there are any cities which belong to multiple countries?" In other words, are there any cities which are part of a condominium?

So I went looking for one, not expecting to find any, and I was right -- there appear to be none. Probably a good job too.

In fact the only decent example of a condominium currently in effect seems to be that of Pheasant Island, which is a condominium of France and Spain. It apparantly is shared on a six-monthly basis between the two nations, which leads to an interesting modelling problem -- a cyclic time-dependent relationship between geography and sovereignty. In other words, it's a time-share! (Stats again).

Anyway, I'll leave that as "an exercise for the reader".

It also raises anther question: back when one needed a passport to cross between the two countries, was a crime commited if a passport-less person was present on the island at the time that sovereignty changed? Perhaps none -- perhaps the condominium agreement allowed people of either nationality to be present on the island at any time, regardless of which state currently was in charge of it. But if the agreement did not allow this then could you charge a person with crossing a border if they were stationary at the time the offence occured?

These thoughts usually turn-up on Fridays, oddly enough. Must be something to do with blood sugar.


At 5:13 AM, Blogger Pete_S said...

I was thinking about the mapping between cities and zip codes today I could never understand ZIP codes, UK postcodes being a more recent invention have a granularity of just a few houses and are nicely hierarchical.

But condominium - places like Basle on the border of Switzerland, France and Germany come close, but still the indivdual districts belong to their own countries - but there are also multinational bodies promoting various common functions.

At 2:38 PM, Blogger David Aldridge said...

Decomposing a UK postal code is a bit of a nightmare though, when you have to take account of formats such as EC1V 0HB etc.. In the end it really comes down to validation by lookup table, and maybe it's the same for US ZIP codes. I don't know if every combination is covered -- 8098x doesn't seem to.

There's a nice applet for looking at what areas are covered by what zip codes here: http://acg.media.mit.edu/people/fry/zipdecode/

Try typing 1, then backspace, then 2, then backspace, then 3 etc.. You can drill down further as well (which is how I found that 8098x doesn't seem to exist.

There are another 4 digits on the end of the 5 digit zip code where better accuracy is needed -- I'm 80922-4303 for example.

I understand that a zip code is technically not an area, but a route. I mdon't know whether postalcodes are the same.

At 12:53 AM, Anonymous Arian said...

Baarle, on the border of The Netherlands and Belgium. The border runs straight through houses and shops.
Imagine, you enter your front-door in Belgium, and leave through the backdoor in Holland.



At 4:17 AM, Anonymous OracleDoc said...

You have wayyyy too much time on your hands.

At 6:01 AM, Blogger David Aldridge said...

Arian -- ah, excellent. Not a condominium as such, but worth it for the human interest factor alone.

OracleDoc -- Yes. Yes, I probably do. :(

At 10:57 AM, Blogger DaPi said...

I'd imagine lots of examples like Baarle - one about 10km from here: a village was carved up between Bern and Savoy in the 1500's and is now Crassier (CH) and Crissey (FR), but essentially one town with a border running through the middle.

Basel & Geneva have French customs zones on Swiss territory - for example flying Paris-Geneva is a French domestic flight. (a risk for your duty-free booze).

At 12:00 PM, Anonymous Arian said...

Yes, I'm sure there are many towns like Baarle. Dapi's comments made me wonder about Vatican City. It's a state of it's own. But if memory serves well, it's under joint jurisdiction from the Italian government (or Roman city council) and the Vatican.
At least, it's patrolled by police from both states.


At 5:50 PM, Blogger Joel Garry said...

There is an interesting building in Lake Tahoe called Cal-Neva. The state line ran through the middle of it (six inch wide yellow IIRC), the gambling went right up to the line in spots, haven't been there lately.

If you get rid of the equal dominion part of the condominium, there's plenty of interesting places, like all those protectorates the zip code finders forget about.

At 2:07 PM, Blogger Niall said...

And of course Berlin used to be a classic example. Fortunately it isn't now.

I expect there might be a few scientific bases in the polar regions with joint ownership as well - though to be honest they might have more pressing needs than data modelling their jurisdiction.


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