'twas brillig (translation: 'not needed')

[LaurV]

Originally Posted by dbaugh

I do high TF-ing of small exponents because with my GPUs I can get a lot of credit fast

This is another point where you should "ask first", if the credit is what you are after, you can get actually more credit by factoring at the LL and DC fronts, than factoring "at extremes" (like too low or too high exponent, too high bitlevel), because mfaktX is "tuned" for those ranges. For example, TF-ing 70M to 74 bits gives you an about 450 GHzDays/Day on a GTX580, but TF-ing a 350M exponent to 72 or 73 bits only gives you 380-399 GHzD/D. I don't have the scores for lower exponents right now, but they also give lower credits for sure.

. My original ID (DB11) from 1997 did not migrate and I lost 317 LLs.

This is a very simple problem to solve for George, you just drop him a PM here (his user is "prime95", he doesn't waste his time to read all these arguments here) with some request and some characteristic of the work you did, and it will be no problem for him to update your scores. He is a very understanding guy.

The first was 2194013. I am revisiting those exponents and ones near them with TF.

Let it go. Working at LL/DC fronts gives you more credits, completes the assignments faster, and you will help the project more. Trust me!

[Mon Nov 09 13:27:31 2015]
M12827821 has a factor: 1426192839661371189084169 [TF:80:81:mfaktc 0.21 barrett87_mul32_gs]
[Mon Nov 09 17:09:41 2015]
found 1 factor for M12827821 from 2^80 to 2^81 [mfaktc 0.21 barrett87_mul32_gs]

This seems very legit to me. When you have "when a factor is found, stop after class", it may take 6 hours (or more, depending on your card) for a class, and the time coincides with what my cards could do. I have no argument here.

Why did I say that "I would not give credit for the lower bits" was because, I assumed (wrongly, it seems) that this factor was found by P-1, and if his factor was found by P-1, than there is no warranty that other smaller factors do not exist. P-1 does not find the smaller factor, but it finds the smoothest factor. If a 81 bits factor is found by P-1, there could be other, undiscovered, smaller factors, which were not so smooth to be P-1 findable.

[dbaugh]

I am glad I was able to put your mind at ease.

When I brought the disappeared id up with George four years ago, his final word was, "There isn't a way to link a v5 account to results that were manually submitted in the v4 era. "

It is just the issue of smaller undiscovered factors that I am concerned about. I know that 12827821 has been trial factored for all factors less than 2^81 because I did it. With the current submission methodology this is not discernable from its exponent status. From the exponent status it is unclear that there are no possible factors in the range of 2^78 to 2^80. Even if someone finds a 100 bit factor there needs to be a way to report that smaller factors have been excluded.

[LaurV]

Originally Posted by dbaugh

Here is a small selection of some other exponents I have searched at these bit levels and beyond with no factors found: 9007753, 9007903, 9027433.
If p-1 is so quick, I asked a couple of years ago for a factor of 9007753. Please find one for me.

I missed that post, due to the other one I replied to.
Ignoring the last sentence, willingly aggressive (or ironical), you did not convince me.
For the three exponents you give as example, you followed the "book procedure" very exactly, which means you know exactly what you are doing. You did the right amount of P-1 in the right place (i.e. after the right bitlevels). [edit: example]

If you followed the same procedure for the 12M exponent, then more than sure you found the factor with P-1.

I think George had his reasons. Sorry.
I am out of this subject.

[alpertron]

Originally Posted by dbaugh

If p-1 is so quick, I asked a couple of years ago for a factor of 9007753. Please find one for me.

According to the ECM report for M9007753, its prime factors have more than 35 digits (116 bits) with high probability. This means that no TF must be done for this number, and P-1 will not be useful.

[Madpoo]

Originally Posted by dbaugh

I am glad I was able to put your mind at ease.

When I brought the disappeared id up with George four years ago, his final word was, "There isn't a way to link a v5 account to results that were manually submitted in the v4 era. "

It is just the issue of smaller undiscovered factors that I am concerned about. I know that 12827821 has been trial factored for all factors less than 2^81 because I did it. With the current submission methodology this is not discernable from its exponent status. From the exponent status it is unclear that there are no possible factors in the range of 2^78 to 2^80. Even if someone finds a 100 bit factor there needs to be a way to report that smaller factors have been excluded.

I think that *typically* someone doing TF work will do it in order, going from smaller bit ranges to higher ones. I think it's safe to assume that in nearly all cases, if a factor was found by TF at some bit level, everything below that was also TF'd.

There are bound to be oddball cases, and then jerks that have been caught finding a factor by P-1 and then "helpfully" submitting "no factor found by TF" results for anything below where they found their factor. It's people like that that make some of us a bit skeptical of cases where a factor should have been easily found by P-1 and then someone claims to have found it by exhaustive TF work, thus getting more credit than they would by merely submitting the P-1 result in the first place. For some people, placing higher on the stats list is apparently worth cheating to get there. Weird.

Anyway, while there are some who like to make sure all the exponents are properly TF'd all the way through, you'll probably find that in most cases, if a factor is found it's not really important anymore if everything up to that was also tried. For some specific numbers or where they have "special meaning" in some way to some one (like you), it may matter more, but in general, a factor means it's composite, move on to the next one.

[Madpoo]

Originally Posted by dbaugh

When I brought the disappeared id up with George four years ago, his final word was, "There isn't a way to link a v5 account to results that were manually submitted in the v4 era. "

I just double-checked and I couldn't find your v4 account either, so George was correct, there's probably nothing to be done for those <= 1997 submissions of yours.

[dbaugh]

LaurV, I am surprised and saddened that you still think I cheated on finding that factor. I know otherwise. TF will find every factor that P-1 will if you TF to a high enough bit level. It does not care that P-1 would have found it with less work. If a high number of my TF searches found big factors I would understand your suspicion but, I have done plenty of high bit level work on other exponents without finding a factor. Try to be less cynical.

DB11 may not be out there but, my name is still associated with those exponents. A search could be done for that name and merged with dbaugh. Or, I could provide a file of all those old results. It is 543 total records. It is not that nothing can be done about migrating this work, it just is not important enough to do it

Thanks everyone, for your feedback and insights. I'll just keep soldiering on as I have for the past 18 years.

Onwards and upwards.

[Batalov]

I think the appropriate metaphor for searching factors could be playing blackjack - in the sense that one may have happened to observe the play for a while and idly counted cards (as some people do professionally) and decided to join the game when you see that the table is hot, or change the table if the table is countably cold.

On the other hand, if you know that the table is as cold as the morgue table (the exponent was ECMd to 116 bits), why would one waste their time to play the game (TF at 80+epsilon bits) with perhaps << 1% of the chance of average winning at the next, completely average table?! Just out of stubbornness? Which is fine, too. It is simply important to understand that one is doing exactly that.

[Madpoo]

Originally Posted by dbaugh

LaurV, I am surprised and saddened that you still think I cheated on finding that factor. I know otherwise. TF will find every factor that P-1 will if you TF to a high enough bit level. It does not care that P-1 would have found it with less work. If a high number of my TF searches found big factors I would understand your suspicion but, I have done plenty of high bit level work on other exponents without finding a factor. Try to be less cynical.

It's the internet where nobody really knows anyone.

Given some of the recent shenanigans with TF results I can understand where he's coming from as far as not trusting someone right away, especially if it seems a little strange.

Don't take it personally though. I think it was just a little strange (and you'd probably agree) to spend so much time taking particular exponents up to such a high TF level for no apparent reason. Now that you've explained why you're going after these exponents specifically, well, it's still a little weird, but I suppose I get it.

Like he said, you'd be better off doing different TF work if you were interested in more credit, but as always, we'd encourage people to participate in any way they think is the most fun. I don't care about credit or ghz/days myself and I've spent a lot of CPU resources on what some would consider wild goose chases, but I enjoyed it.

[dbaugh]

Surprisingly, this is not the first time weird and I have been in the same room. ;) I guess the takeaway from all of this is that I should stop my TF run on 9007753 from 2^82 to 2^83. That one bad residue is never going away even if I find a factor. I also need to be more careful about the order in which I submit results. I use my CPUs mainly for adding to OEIS. TF on my GPUs has such a high cost/benefit that it is irresistible to me. I should probably start looking for factors of non-LLed exponents. If LL ever gets really fast on a GPU, watch out.

[Batalov]

Originally Posted by dbaugh

That one bad residue is never going away even if I find a factor.

Right! Anyone who didn't have a bad residue... ...

Well, like the old saying --