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If you call me like this, I will pop in, even if my memory about the subject is bad.
Here we go. (All the following info is modulo "IIRC"):Pokes:
PSP gives credit for factors as a function of n and p the factorsize, end of discussion. Note that even factors get credit that might reveal to be useless, because a prime is found before they save an LLR test.
At SoB, the story is more difficult. Here, factors are like a bank deposit that you can't withdraw immediately. The thing is that a factor only scores when it has actually saved an LLR test.
Say, you submit a factor for n=16M. You get no (or only marginal, I don't know) score for the moment. When in one or two years, firstpass LLR reaches 16M, your factor will save a LLR test, and you get your score. Now, imagine, a prime is found for the k of your factor. So doublecheck will never be done, and your factor does not score again. If no prime is found, however, it will, a couple of years later.
Why do the factors above 20 M not appear at all? Because a couple of years back, we switched from sieving until 20M to until 50M, and the script and the scoring system and everything has not been updated yet. However, factors above 20M will save a test only in 10 years or so, so until then, this might become fixed.
As you know, factors can be found by sieving, and P-1. While sieving just tries all p for any n, and hence gets factors for randomly scattered n, with P-1, we search any factor p for n that we can fix. So, we search for factors for n just above the firsrpass level, in order to save these 2 LLR tests before it is too late. To make this more interesting, there is something called "active window". Factors in this active window (n between firstpass and firstpass+300000 or so) score twice as much. You might be lucky and find such a factor by sieving, but you are sure about that for P-1. Additionally, P-1 saves LLR tests soon, and hence you get youre score soon.
PLEASE don't be angry with this system, and SUBMIT EVERYTHING YOU FIND, even if you have to wait a little eternity until you see the effects. If you want sieveing credits immediately, I suggest BOINC, which gives you even credits if you don't find a factor.
Lengthy post, but it's no easy subject.
Glad to help, H.
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Thanks for the reply this clarifies it.
So in time the script will be changed and I might get credit for the "excluded" factors. But if I want to get credit soon, I need to do P-1.
I'll check P-1 out then :)
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balachmar,
Humm.. if memory serves me correctly one will not recieve credit for excluded factors.
Excluded factors are a little weird and why the client reports them I'm not sure.
The reason why excluded factors don't count is pretty simple really.
An excluded factor is not needed since another (generally) smaller factor has already be found for the same k/n pair. So basically even though its a real factor it wasn't needed because we already factored out the k/n pair.
If you look at the k/n pair that your factor sieved out you will actually see that that k/n pair does not exist in the database.
Why these factors are generated I don't know... I think it has something to do with the fact that one factor cannot factor more than 1 valid k/n pair, so if a k/n pair is found that your p matches there is no need to factor further with that p and the client moves on. I guess this makes the client a little faster. ( On why exactly, i'm not sure (recalling from memory) but I know they won't credit.)
I probably have a couple thousand of these...
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Well, excluded factors like double check in general SoB. I prefer to have two different factors for k*n pair, just to be sure. And AFAIK, some SoB primes come from second pass )))
