Oracle FAQ Your Portal to the Oracle Knowledge Grid
HOME | ASK QUESTION | ADD INFO | SEARCH | E-MAIL US
 

Home -> Community -> Usenet -> comp.databases.theory -> Re: Computational complexity (was Re: Normalisation)

Re: Computational complexity (was Re: Normalisation)

From: Jon Heggland <heggland_at_idi.ntnu.no>
Date: Tue, 19 Jul 2005 10:40:20 +0200
Message-ID: <MPG.1d46dada2a522faf9896fa@news.ntnu.no>


In article <11dodnf29qpvma1_at_corp.supernews.com>, misha_at_no_mishapen_spam.co.uk says...
> > Estimating complexity on Turing machines is one thing; doing it for
> > usable programming languages / systems is slightly different. I know
> > theory, but not *all* theory. Sorry, but we can't all be omniscient.
>
> The programming language (and the constant space/time assumptions for
> "int") are an abstraction -- and (like all abstractions) are leaky[1].

Hm? The Turing machine is even more of an abstraction. Neither technique is ideal. It depends on the circumstances which one is best to use, and the circumstances I am used to strongly favour one over the other.

> <oldfartmode>I dunno, kids these days with their fancy dual-core Athlons
> -- whatever happened to coding assembler to fit in a 256 byte page?

Or using microcode to construct instruction sets? That was good fun, actually.

> > Sophistry. This is the kind of thing that gives theory a bad name.
>
> No. Reality.

Everything is reality at some level. But sorry; I meant the debating technique as much as the idea of counters taking log n space.

> Engineering is the process of balancing the constraints of physical
> reality with cost and requirements. To do that you must _know_ the
> constraints.

Agreed. But it is no better to be unaware of "practical" complexity assessment than to quietly ignore the complexity associated with strings of unbounded lengths (unless they are specifically called for), I think.

> [1] Jon better not apply for a job at Fog Creek, me thinks
> (http://www.joelonsoftware.com/articles/fog0000000319.html).

I don't know where you got the impression that I am unaware of (? or opposed to?) that kind of considerations.

-- 
Jon
Received on Tue Jul 19 2005 - 03:40:20 CDT

Original text of this message

HOME | ASK QUESTION | ADD INFO | SEARCH | E-MAIL US