it would be trivial to write a generator of simple s-exps to evaluate...
(define (generate-challenge)
(let* ((op (random 4))
(pl (random 2))
(x1 (+ 1 (random 10)))
(x2 (+ 1 (random 10)))
(c ((case op ((0) +) ((1) -) (else *)) x1 x2))
(an (if (= 3 op) n1 c)))
(cons (sprintf "Result of evaluating ((lambda (x) (~A ~A ~A)) ~A)?"
(case op ((0) "+") ((1) "-") ((2) "*") ((3) "/"))
(if (= 0 pl) "x" (if (= op 3) c n1))
(if (= 0 pl) n2 "x")
(if (= 0 pl) (if (= op 3) c n1) n2)a)
an)))
would be a simple arithmetic generator. (apologies for any errors and for
the formatting, i didnt want it to take a whole page properly formatted, and
i just wrote this on the fly, so there may be a few bugs)
-elf
On Tue, 7 Nov 2006, Alejandro Forero Cuervo wrote:
> > Perhaps as an anti-spam measure we could require answers to some
> > simple Scheme questions; for instance, in order to create/edit a page,
> > one would need to correctly input the answer to a question such as:
> >
> > What is the result of evaluating ((lambda (x) (/ 42 x)) 7) ?
> >
> > While very quick and simple for any schemer to answer, I'd say a
> > spammer who is able to answer that (almost) deserves his edit
> > privileges ;-)
>
> I am not sure this is that worth implementing, but I guess we can
> experiment. :-)
>
> I guess we want the questions to be as simple as possible (so, for
> example, they won't keep people to make small contributions here and
> there) while still keeping the spammers from defacing our wiki. I
> will begin with easy questions (such as "What's 12 + 3?" or "What's
> character #3 in the word 'random'?") and see if they are good enough
> to stopping spam. I suspect not but it could be that this spam is
> comming from an automated bot that attacks all sorts of wikis and that
> this simple questions turn out to be good enough to keep it from
> altering our wiki. (I suspect the spamming of our wiki is being done
> manually, not programmatically, but I really don't know.)
>
> I will, of course, also make it so at the Nth (3rd?) wrong answer, an
> IP is banned for a while.
>
> Something else we need to look at is how to use svnlook to alter the
> commit log for one change directly in the svn repos (since the spammer
> could put the spam in the descriptions for the changes).
>
> Alejo.
> http://azul.freaks-unidos.net/
>
>
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>
>
-----
Humans always do the most intelligent thing after every stupid alternative
has failed. -- R. Buckminster Fuller
A year spent in artificial intelligence is enough to make one believe in G-d.
-- Alan Perlis
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