Thread: What's next?
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Old 2004-09-15, 16:14   #34
Wacky
 
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Jun 2003
The Texas Hill Country

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You cannot. Although the server infrastructure supports multiple projects, we generally work (publicly) on only one at a time. When projects require a month or more to collect an adequate number of relations, it is better to get one finished and then start the next.

However, in the present case, the numbers selected are "easy" (in comparison to those that we have been factoring). We could sieve each of them in a week. However, there are two problems in doing that. First, there is the immediate post-processing. I am just now completing the filtering for 11,199- and we are still working on 3,491+ to try to get a more reasonable matrix. Therefore, I don't need another one to finish just yet.

But there is also the efficiency aspect. For every new factorization, each siever must compute the factor base. That "cost" is then amoritized over the lines sieved. Therefore it is more efficient to allow each siever to run for a couple of weeks on one number and ignore the other one.

There is also a problem in collecting all of the work done. Most results are returned within a few hours. However, some routinely get delayed for a day or so. A few even show up weeks after a project is completed. Obviously we cannot know when, if ever, delayed results will show up. Therefore, some of those results, particularly near the end of a project, will not be used. This is more significant when the projects are very short.

For these reasons, I chose to split the sievers into two camps and work on a separate factorization in each one.

Richard
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