ok 'm not proposing to scan he code.
simple protocol etique will suffice
Jay
----- Original Message -----
From: "Guy Smith" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Friday, May 11, 2001 6:44 PM
Subject: RE: [freenet-tech] Off-Topic: Ideas for a FreeNet Process
> Please don't be offended by this, but you're being myopic. The example I
> gave with bounded for loops was off the top of my head, and was simply to
> illustrate a SINGLE CLASS of software that can be solved. There are all
> sorts of other categories that can be solved; the fact that I did not
> enumerate them does not mean they do not exist. So don't cite that one
> example as being the sum total of all possible software that can be
proven.
> All it means is that I haven't spent enough time on the subject to list
> other possibilities; but this thread is only two hours old, so what do you
> want? I'll invent the entire field of mathematics in my next post.
>
> Here's a question: you're handed a function along with a proof that the
> upper bound on the running time is n^2 and the average running time is n
log
> n. Has the halting problem been solved for this function? YES! And
here's
> the shocker: that proof (for Quicksort) can be verified by a machine! Are
> you going to claim that Quicksort is not a useful function?
>
> Another question: have you EVER written a program for which you did not
know
> the running time? Because any person who tries to ship a program (and
we're
> assuming here that the software WILL be shipped to a great many users)
> without knowing if there are (undesired) infinite loops in the code is
> simply irresponsible. The point being that programmers are solving the
> halting problem for their algorithms ALL THE TIME. That's why we care so
> much about big-oh -- it not only tells us what the answer to the halting
> problem is, but it also tells us how long we can expect to wait!
>
> If we want to be really strict, we should simply require that for every
> program written, the programmer should also write a proof describing the
> running time of the code, memory utilization, etc. Which programmers
should
> do anyway, so this would just enforce good practice. But that's probably
> asking too much. After all, I shouldn't talk; I don't write proofs for my
> code. At least, not *rigorous* proofs. But I CAN give you upper bounds,
> which is all I need to be able to say that I've solved the halting
problem.
>
> Undecidablity proofs are interesting in that they tell us the LIMITS of
what
> can be done. They don't tell us about what NORMALLY can be done.
>
> As for the automatic downloading of software; god help us when our
computers
> start downloading code without our permission. But if we want them to do
> that, then we sure better put restrictions on what can run; and I, for
one,
> would be very happy to ban web servers and other infinite loops from my
> machine, even if it means that I lose out on the occasional "useful"
> program.
>
> --Guy
>
> -----Original Message-----
> From: Mike Schiraldi [mailto:[EMAIL PROTECTED]]
> Sent: Friday, May 11, 2001 4:46 PM
> To: [EMAIL PROTECTED]
> Subject: Re: [freenet-tech] Off-Topic: Ideas for a FreeNet Process
>
>
> > One would assume that the software was not downloaded automatically. A
> > person, somewhere, decided that he/she wanted the software to begin
with.
>
> I thought that the whole point of this proposal was that the software
> actually was downloaded automatically, without any action or notification
of
> the owner of the machine -- an extension of the Freenet "nobody knows
> exactly what's stored on their node" philosophy to "nobody knows exactly
> what's running on their node".
>
> Stefan brought up the difficulty of preventing endless loops or other
> resource hogs, and JF's proposed solution was to scan code before running
> it. But as the record player stories in "Godel, Escher, Bach" brilliantly
> illustrate, that approach cannot succeed.
>
> Your scanner can always be tricked, it's a mathematical fact, unless you
> restrict code to the kind of bounded loops you brought up. But if you only
> run bounded-loop code, you're shutting out virtually all useful
> programs. Anything that acts like a server. Anything that looks like an
> application -- imagine if Microsoft Word said, "Sorry, i'm only allowed to
> loop one more time before i have to terminate. Oops, there it goes. Bye!"
>
> However, just because the scanner approach can't work, all is not lost.
>
> A task scheduler might work. Let a subprocess run for a set amount of
time,
> then swap it out. And like Freenet's "cache data closer and closer to the
> requesters" policy, such a network could move the process closer and
closer
> to the person who's running it -- that way, someone who tries to DOS the
> network with hundreds of little dumb programs will find those little dumb
> programs moving closer and closer, until only the nearest node is dragged
to
> a halt.
>
>
> --
> Mike Schiraldi
> Verisign Applied Research
>
> _______________________________________________
> freenet-tech mailing list
> [EMAIL PROTECTED]
> http://lists.freenetproject.org/mailman/listinfo/tech
>
> _______________________________________________
> freenet-tech mailing list
> [EMAIL PROTECTED]
> http://lists.freenetproject.org/mailman/listinfo/tech
>
_______________________________________________
freenet-tech mailing list
[EMAIL PROTECTED]
http://lists.freenetproject.org/mailman/listinfo/tech
