

How Allies Used Math Against German Tanks - Luyt
http://www.wired.com/autopia/2010/10/how-the-allies-used-math-against-german-tanks/

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RiderOfGiraffes
If you care to search you'll find that this story has appeared here on HN
several times in the past several months. There has been much discussion,
again and again. I'm currently on my mobile and can't easily search for you.

EDIT:

OK, I've got to a proper computer and here are some search results:

<http://news.ycombinator.com/item?id=670218>

<http://news.ycombinator.com/item?id=1421698>

<http://news.ycombinator.com/item?id=1818166>

Each of these has substantial discussion, and I'm pretty sure there are more.

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mivok
If you like stories like this, there are a number of similar stories (e.g.
this one, cracking the enigma code, protecting convoys) in a book called The
Pleasures of Counting: [http://www.amazon.com/Pleasures-Counting-T-
W-K%C3%B6rner/dp/...](http://www.amazon.com/Pleasures-Counting-T-
W-K%C3%B6rner/dp/0521568234) \- it's not all world war 2, but is very
interesting and does contain a lot of information on the math used during the
war.

------
lucasjung
When I saw the headline, I my first thought was that the math was something
along the lines of:

A = number of U.S./allied tanks in each battle

D = number of German/axis tanks in each battle

A >= 2D

------
bl4k
or why to not put autoincrement id's into your webapp routes

~~~
Luyt
...because others then can find out how many visitors your site gets? Or
perhaps nastier things, like guessing id's?

~~~
jjwiseman
Previously: <http://news.ycombinator.com/item?id=670218>,
<http://news.ycombinator.com/item?id=1818166>, joshu:
<http://joshua.schachter.org/2007/01/autoincrement.html>
(<http://news.ycombinator.com/item?id=52429> )

Foursquare growth in 2009 inferred from autoincrement IDs:
<http://www.flickr.com/photos/wallofhair/4232092914/>

~~~
gojomo
For some services, your growth may not be proprietary info — you may want to
show incrementing IDs off, or make all your artifacts trivially discoverable.

But, if you have an internal autoincrement ID that you want to obfuscate,
what's the best simple practice, minimizing token expansion?

~~~
smanek
Just use UUIDs and be done with it. I'll give you a $1 if you ever see a
collision ;-)

~~~
gojomo
That's a reasonable baseline suggestion, but I'd prefer any technique to
generate more compact public IDs.

~~~
buddydvd
[http://www.quora.com/How-do-you-symmetrically-
encrypt-32-bit...](http://www.quora.com/How-do-you-symmetrically-
encrypt-32-bit-auto-increment-IDs-to-avoid-using-64-bit-UUIDs-to-conceal-the-
size-and-order-of-a-database-table/answers/23925)

