Re: Mersenne: On v18 factoring

[gann]

Is there any kind of assignment that will force the client to try to calculate a divide by zero and crash? Or would other safe testing still be desired?   <><><><><><><><><><><><><><><><><><><><><><><><><><><><> Subscribe to The Gann Letter if you are interested in: varying levels of humor/jokes/quotes, parody/satire, science/space/technology items, cool news, games, programs, pics, and other interesting stuff.   subscribe #1: [EMAIL PROTECTED] subscribe #2: http://groups.yahoo.com/group/TheGannLetter/join subscribe #3: gann (at) ganns.com read online : http://ganns.com/TheGannLetter <><><><><><><><><><><><><><><><><><><><><><><><><><><><> ----- Original Message ----- From: Brian J. Beesley To: [EMAIL PROTECTED] Sent: Wednesday, October 23, 2002 1:52 AM Subject: Re: Mersenne: On v18 factoring On Tuesday 22 October 2002 19:09, Gordon Bower wrote: > [... snip ...] > Does anyone have any suggestions for how to stop a runaway copy of > v18? Perhaps in a few weeks the server can be updated to return an "out of > exponents" error to v18 instead of offering it an assignment it can't > handle? This is not trivial - if you do this then a "broken" client will probably request another assignment immediately - thus trapping the client and the server into a vicious circle. Whilst the client can go hang for all anyone else cares, the effects on the server would probably be much the same as handing out an "unacceptable" assignment. Other people have mentioned the possibility of "automatically" disengaging or updating the client. I have very serious reservations about this; the problem is that it leaves the system hosting the client wide open to use of the mechanism for malicious purposes, e.g. "updating" to a client containing a trojan or switching it to a different project, or attacking a user by disengaging his systems so that you can leapfrog him in the league tables. I'm afraid that I would have to withdraw my systems from the project, and recommend that other people did the same, if any such capability was added to the client. Given that the server can tell the difference between a v18 client and a later one, would it not make most sense to have the server assign a LL test on the _highest_ unallocated exponent which v18 can handle if a v18 client asks for a factoring assignment and none suitable are available. This action would effectively remove the client from the loop for a while (probably a few months, given that most v18 clients will be running on slowish systems), thereby alleviating the load on the server, and buying time to contact the system administrator - when this is still relevant, of course. And some useful work may still be completed, eventually! Regards Brian Beesley _________________________________________________________________________ Unsubscribe & list info -- http://www.ndatech.com/mersenne/signup.htm Mersenne Prime FAQ      -- http://www.tasam.com/~lrwiman/FAQ-mers