Re: Python from Wise Guy's Viewpoint

From: Joachim Durchholz (joachim.durchholz_at_web.de)
Date: 10/27/03 

Date: Mon, 27 Oct 2003 22:16:04 +0100

Erann Gat wrote:

> In article <bnhnhq$5fe$3@news.oberberg.net>, Joachim Durchholz
> <joachim.durchholz@web.de> wrote:
>
>
>>I wouldn't detect spam using a regexp
>>anyway, I'd use a Bayesian filter which is more adaptable to personal
>>taste - one person't spam it another person't bed lecture.
>
>
> Agreed, but you can't prove a Bayesian filter "correct" either for that
> very reason.

Hey, I can prove it correct according to specification.
The difference is that I can draw one up for a Bayesian filter: it's
essentially a specification how user input should be used to classify data.
The actual behaviour of the filter for each given spam isn't specified
(and cannot be since it depends on user input, which is inherently
unspecifiable) - but when I'm the program's maintainer, I don't care
much about how each mail is classified, I care about other properties of
the program, namely that it adjusts the word probabilities according to
specification and user input. (/This/ is a concrete example of what I've
been trying to say constantly: that a correctness proof for a program
need not cover all of its input and output. That talking about a
program's "correctness" in general isn't very fruitful - those ideas
about Goedel undecidability theorems that have been floating around in
this thread are both correct and entirely irrelevant, I haven't seen a
single program in my life where this kind of borderline case was even
remotely relevant.)

Regards,
Jo