[OSM-talk] address interpolation

Jochen Topf jochen at remote.org
Fri Oct 2 08:45:30 BST 2009

On Wed, Sep 30, 2009 at 10:24:06AM +0100, David Earl wrote:
> And I think the previous point about other alphabets is a red herring 
> too: basically "no letter" can precede all other letters in whatever 
> alphabet. If there's ambiguity in the alphabet due to the glyph 

The problem is as follows:

You see an interpolation "25a to 25c". How do you know that this means
"25a, 25b, 25c"? You know by removing the number and then starting with
the "a" go through code points adding one until you reach "c". Easy.
This will work for all alphabets where that are layed out in alphabetical
order in Unicode, and they probably all are. (but thats an assumption on
my part :-)

But, when you see an interpolation "25 to 25c". How do you know that this
means "25, 25a, 25b, 25c"? You again remove the number. That gives you the
first entry. But what happens then? You have to look at the "c", decide that
thats a latin alphabet, the first letter of that is "a" and you go on with

So you have to know all letters in all alphabets in the world to make this
algorithm work. It might not be a big deal in practice, just another case
where our assumptions might not hold everywhere.

Jochen Topf  jochen at remote.org  http://www.remote.org/jochen/  +49-721-388298

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