Symmetric Prime Tuples development

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Tomáš Brada
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Message 3640 - Posted: 11 Oct 2019, 21:59:18 UTC

I tried my luck at re-writing the program. It was quite fun. My program is 70 lines long. The original is 268 :)
There are places to optimize, but not without benchmarks.
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Message 3641 - Posted: 13 Oct 2019, 22:05:37 UTC

In reaction to message about stop@home I started developing application for search of such symmetric prime tuples.
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Message 3642 - Posted: 13 Oct 2019, 22:10:47 UTC

New application Up! Codename SCPN (will change maybe).
The workunit "scpn_beta1" was submitted to evaluate how it behaves.
Estimated runtime 30 minutes (i5-5200U).
Checkpoints do not work yet. The app checkpoints, but does not resume from checkpoint. That's why the quorum is set to 8 only.
This is non-interactive test (closed alpha stage). I will watch everything and analyse results/failures and I do not expect any feedback from users yet.
Eventually, I will call for interactive test, where feedback will be welcome.
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Message 3643 - Posted: 14 Oct 2019, 7:56:49 UTC

I was so asleep that I forgot I coded the checkpoint resume already. The application should even resume from checkpoints.
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Message 3644 - Posted: 14 Oct 2019, 14:20:36 UTC
Last modified: 14 Oct 2019, 14:30:36 UTC

First batch of workunits "scpn_xxx_b" in batch 42!
Estimated runtime: 2 hours (i5-5200U). The app checkpoints.
We scan the range 500002700000000000 to 500007900000000000 for symmetric prime tuples.
This range was already scanned and the results are here. We scan the same range to check consistency of this boinc app.
Previous batch 41 was faulty - it attempted to search for 0-tuples :)
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Message 3645 - Posted: 14 Oct 2019, 16:19:53 UTC - in response to Message 3643.  

I knew i forgot something. The app does not report the checkpoint to boinc, which also messes up other boinc aspect. I think the batch will finish, regardless.
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Message 3646 - Posted: 14 Oct 2019, 18:41:30 UTC
Last modified: 14 Oct 2019, 20:09:23 UTC

I had the AmAZiNg (irony) idea of only storing half of the tuple coefficients (cause the other half is symmetric). But that is not unique encoding! So to modify the output format again.

For example, what is stored: 500002767573021263: 56, 48, 6, 166, 72, 96, 12, 2
there are 8 offsets. This could be expanded into symmetric dispacements like this:
0, 56, 48, 6, 166, 72, 96, 12, 2, 12, 96, 72, 166, 6, 48, 56 or like this
0, 56, 48, 6, 166, 72, 96, 12, 2, 2, 12, 96, 72, 166, 6, 48, 56.
The second one is wrong. So I fixed it already in code.
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Natalia Makarova
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Message 3648 - Posted: 14 Oct 2019, 19:32:16 UTC - in response to Message 3646.  
Last modified: 14 Oct 2019, 19:37:33 UTC

I had the AmAZiNg idea of only storing half of the tuple coefficients (cause the other half is symmetric). But that is not unique encoding! So to modify the output format again.

For example, what is stored: 500002767573021263: 56, 48, 6, 166, 72, 96, 12, 2
there are 8 offsets. This could be expanded into symmetric dispacements like this:
0, 56, 48, 6, 166, 72, 96, 12, 2, 12, 96, 72, 166, 6, 48, 56 or like this
0, 56, 48, 6, 166, 72, 96, 12, 2, 2, 12, 96, 72, 166, 6, 48, 56.
The second one is wrong. So I fixed it already in code.

Please keep the generally accepted tuple format!

500002767573021263: 0 56 104 110 276 348 444 456 458 470 566 638 804 810 858 914

or
500155744849852957: 0,24,66,90,120,130,144,154,186,196,210,220,250,274,316,340

Both of these formats are supported by my square builder program.
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Message 3649 - Posted: 14 Oct 2019, 20:02:54 UTC - in response to Message 3648.  
Last modified: 14 Oct 2019, 20:08:05 UTC

Please keep the generally accepted tuple format!

Yes.
I already fixed the issue in code and it will be deployed in next test batch.
I want to first process results of the current batch to catch any other problems.
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Message 3653 - Posted: 15 Oct 2019, 15:28:47 UTC

Batch 43 checking in range 500266350516360713..500286766859602800.
Double-checking results from Xaver.
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Message 3654 - Posted: 15 Oct 2019, 15:52:22 UTC - in response to Message 3653.  

Batch 43 checking in range 500266350516360713..500286766859602800.
Double-checking results from Xaver.

What are the results of the previous batch?
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Message 3655 - Posted: 15 Oct 2019, 16:24:22 UTC - in response to Message 3653.  

Batch 43 checking in range 500266350516360713..500286766859602800.
Double-checking results from Xaver.


I'm seeing some strange behavior with these tasks.

First thing is they have a short deadline -- about 25 minutes, and they're going to take about 4 or 5 hours to run.

Second problem is even though there's 4 cores on the computer, and 4 tasks were downloaded, only 1 task is running. I don't know why. There's enough memory to run more than one task, so that doesn't appear to be the problem. I'm not sure if this is a problem on your end or my end.

Between the two problems, you can expect lots of automatically aborted tasks because of this. As soon as the (short) deadline passes, BOINC will automatically abort the three unstarted tasks, and immediately download three more. When their deadline passes, they will be aborted and replaced with three more, and so on.
Want to find one of the largest known primes? Try PrimeGrid. Or help cure disease at WCG.

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Message 3656 - Posted: 15 Oct 2019, 16:47:46 UTC - in response to Message 3655.  
Last modified: 15 Oct 2019, 16:48:31 UTC

I missed one digit while setting the deadline and I corrected it very shortly after. But some tasks are already downloaded and it does not propagate to clients. Also boinc should not download the task if it knows it can't meet the deadline, so not sure how that happened.

Not sure about the only one task running. Maybe that is the consequence of the short deadline? Or memory requirement. There is only placeholder value in the ram requirement field.
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Profile Michael Goetz
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Message 3657 - Posted: 15 Oct 2019, 17:08:05 UTC

<rsc_memory_bound>100000000.000000</rsc_memory_bound>


That's from one of these tasks. That's 100 MB. (I think)

Actual usage is 357.91 MB according to BOINCTasks. Maybe that's got something to do with it?
Want to find one of the largest known primes? Try PrimeGrid. Or help cure disease at WCG.

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Message 3658 - Posted: 16 Oct 2019, 6:23:14 UTC - in response to Message 3657.  

I found out that the feeder respects priority only on startup. If high priority tasks run out, low priority tasks will take their place and wont go away even if low priority tasks appear. It seems the allapps option is needed even thou I dp not like it.
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Message 3659 - Posted: 16 Oct 2019, 11:38:53 UTC

Batch 43 revealed that there is a error in detection of odd-k tuples. There were 37 k=17 reported, but none of them are prime above index 10.
All two k=18 tuples were correctly found, so that's good.
Later I will check whether all k=16 are correct.
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Message 3660 - Posted: 16 Oct 2019, 11:55:28 UTC
Last modified: 16 Oct 2019, 12:02:00 UTC

k=17 ?
500266632926148299: 0 14 44 50 68 72 134 212 294 330 408 470 474 492 498 528 542
I checked for primality, and all all prime here.
Is this tuple correct? I need help with the odd-k tuples.
There are 40 odd-k tuples in the database from batch 43.
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Message 3661 - Posted: 16 Oct 2019, 12:53:14 UTC - in response to Message 3660.  

Error with central element 294.
In a symmetric tuple, the central element is d/2, d is the diameter of the tuple.
In your example, d=542.
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Message 3662 - Posted: 16 Oct 2019, 13:09:20 UTC

Tomáš Brada
Pay attention to this definition

k-tuple (p + a1, p + a2, p + a3, ..., p + a [(k-1) / 2], p + a [(k-1) / 2 + 1], p + a [(k-1) / 2 + 2], ..., p + a [k-2], p + a [k-1], p + ak) for k odd called symmetric, if the following condition is satisfied:

a1 + ak = a2 + a[k-1] = a3 +a [k-2] =…= a[(k-1)/2] + a[(k-1)/2+2] = 2 a[(k-1)/2+1]

Example
symmetric 5-tuple

18713: 0, 6, 18, 30, 36

https://www.primepuzzles.net/problems/prob_062.htm
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Message 3663 - Posted: 16 Oct 2019, 13:22:33 UTC

I used to check tuples in Wolfram Alpha,
for example
Select[Range[0,240],PrimeQ[1006882292528806742267+#]&]

result
{0, 6, 24, 36, 66, 84, 90, 114, 120, 126, 150, 156, 174, 204, 216, 234, 240}

Now it doesn’t work for me. I can not understand the reason :(
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