From: Matthias Andree <ma@dt.e-technik.uni-dortmund.de>
To: ding@gnus.org
Subject: Re: pop3 speedup
Date: Mon, 26 Sep 2011 22:09:39 +0200 [thread overview]
Message-ID: <4E80DC03.2030706@dt.e-technik.uni-dortmund.de> (raw)
In-Reply-To: <87zkhrulgw.fsf@gmail.com>
Am 26.09.2011 21:55, schrieb Antoine Levitt:
> 26/09/11 21:35, Lars Magne Ingebrigtsen
>> Antoine Levitt <antoine.levitt@gmail.com> writes:
>>
>>> Nope, it's n^2, polynomial (1 + 2 + 3 + 4 ... + n is about n^2/2).
>>
>> Darn.
>
> Don't worry, you'll get it next time.
>
> (actually, it's pretty hard to do something exponentially on a list
> structure. You'd have to run a non-trivial recursion. And then, of
> course, find something to do with it.)
The text book example of something recursing deeply and thus massively
is the two-argument Ackermann function.
Typical exponential problems are certain kinds of perfect optimization
problems and quite a lot of scheduling problem classes, among them the
travelling salesman problem.
--
Matthias Andree
next prev parent reply other threads:[~2011-09-26 20:09 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-09-26 18:37 Lars Magne Ingebrigtsen
2011-09-26 19:16 ` Matthias Andree
2011-09-26 19:29 ` Lars Magne Ingebrigtsen
2011-09-26 19:34 ` Antoine Levitt
2011-09-26 19:35 ` Lars Magne Ingebrigtsen
2011-09-26 19:55 ` Antoine Levitt
2011-09-26 20:09 ` Matthias Andree [this message]
2011-09-26 20:01 ` Matthias Andree
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