Welcome to the Winter Solstice Challenge
The Final Challenge of the 2017 Challenge series is upon us. The Winter Solstice Challenge will be a 3 day (72 hour) celebration on account of the winter solstice. The challenge is being offered on PrimeGrid's most successful sieve, the Proth Prime Search (Sieve) application. Come join us and warm yourself by the Solstice fires!
The Winter Solstice...a predictable event in nature that has occurred for billions of years. A way point in the cyclic motion of the Universe. Many of the today's major winter festivals and celebrations can trace their origins back to this event...the longest night of the year (or the shortest day).
We'd like to wish everyone a Happy Holiday...whatever festival or celebration you may observe.
NOTE: The servers are located in the Northern Hemisphere; therefore, we'll observe winter. However, the Southern Hemisphere will be experiencing the Summer Solstice.
To participate in the Challenge, please select only the PPS (Sieve) project in your PrimeGrid preferences section. The challenge will begin 18 December 2017 16:28 UTC and end 21 December 2017 16:28 UTC. Application builds are available for the following:
- Microsoft Windows (98 or later) running on an Intel x86-compatible CPU 1.41 (openclatiPPSsieve)
- Microsoft Windows (98 or later) running on an Intel x86-compatible CPU 1.39 (cudaPPSsieve)
- Microsoft Windows (98 or later) running on an Intel x86-compatible CPU 1.39 (cpuPPSsieve)
- Microsoft Windows running on an AMD x86_64 or Intel EM64T CPU 1.39 (cpuPPSsieve)
- Linux running on an Intel x86-compatible CPU 1.41 (openclatiPPSsieve)
- Linux running on an Intel x86-compatible CPU 1.39 (cudaPPSsieve)
- Linux running on an Intel x86-compatible CPU 1.39 (cpuPPSsieve)
- Linux running on an AMD x86_64 or Intel EM64T CPU 1.41 (openclatiPPSsieve)
- Linux running on an AMD x86_64 or Intel EM64T CPU 1.39 (cudaPPSsieve)
- Linux running on an AMD x86_64 or Intel EM64T CPU 1.39 (cpuPPSsieve)
- Mac OS 10.4 or later running on Intel 1.39 (cpuPPSsieve)
- Mac OS 10.4 or later running on Intel 1.39 (cudaPPSsieve)
- Mac OS 10.5+ running on an Intel 64-bit CPU 1.39 (cpuPPSsieve)
- Mac OS 10.5+ running on an Intel 64-bit CPU 1.39 (cudaPPSsieve)
- Mac OS 10.5+ running on an Intel 64-bit CPU 1.49 (openclatiPPSsieve)
Time zone converter:
The World Clock - Time Zone Converter
NOTE: The countdown clock on the front page uses the host computer time. Therefore, if your computer time is off, so will the countdown clock. For precise timing, use the UTC Time in the data section to the left of the countdown clock.
Scores will be kept for individuals and teams. Only work units issued AFTER 18 December 2017 16:28 UTC and received BEFORE 21 December 2017 16:28 UTC will be considered for credit. Since this is a fixed credit project, we'll be using cobblestones for scoring.
Credit is currently set at 3371 cobblestones per WU.
At the Conclusion of the Challenge
We would prefer users "moving on" to finish those tasks they have downloaded, if not then please ABORT the WU's instead of DETACHING, RESETTING, or PAUSING.
ABORTING WU's allows them to be recycled immediately; thus a much faster "clean up" to the end of an LLR Challenge. DETACHING, RESETTING, and PAUSING WU's causes them to remain in limbo until they EXPIRE. Therefore, we must wait until WU's expire to send them out to be completed.
Please consider either completing what's in the queue or ABORTING them. Thank you. :)
About the Proth Prime Search
The Proth Prime Search is done in collaboration with the Proth Search project. This search looks for primes in the form of k*2^n+1. With the condition 2^n > k, these are often called Proth primes. This project also has the added bonus of possibly finding factors of "classical" Fermat numbers or Generalized Fermat numbers. As this requires PrimeFormGW (PFGW) (a primality-testing program), once PrimeGrid finds a prime, it is then tested on PrimeGrid's servers for divisibility.
Our initial goal was to double check all previous work up to n=500K for odd k<1200 and to fill in any gaps that were missed. We accomplished that, increased the goal to n=800k, then expanded to include sub-project Proth Prime Search Extended (PPSE) for odd 1,200<k<10,000 and the Proth Mega Prime Search of numbers larger than 1m decimal digits for odd k<1200. Small primes are still important as they may lead to new factors for "classical" Fermat numbers or Generalized Fermat numbers. While there are many GFN factors, currently there are only about 334 "classical" Fermat number factors known. Current primes found in PPS definitely make it into the Top 5000 Primes database.
We're currently searching n>2.54m for odd 300<k<600 in PPS, n>1.46m for odd 1200<k<10,000 in PPSE and n>3.44m for odd 500<k<1200 in the Proth Mega Prime Search.
For more information about "Proth" primes, please visit these links:
About Proth Search
The Proth Search project was established in 1998 by Ray Ballinger and Wilfrid Keller to coordinate a distributed effort to find Proth primes (primes of the form k*2^n+1) for k < 300. Ray was interested in finding primes while Wilfrid was interested in finding divisors of Fermat numbers. Since that time it has expanded to include k < 1200. Mark Rodenkirch (aka rogue) has been helping Ray keep the website up to date for the past few years.
Early in 2008, PrimeGrid and Proth Search teamed up to provide a software managed distributed effort to the search. Although it might appear that PrimeGrid is duplicating some of the Proth Search effort by re-doing some ranges, few ranges on Proth Search were ever double-checked. This has resulted in PrimeGrid finding primes that were missed by previous searchers. By the end of 2008, all new primes found by PrimeGrid were eligible for inclusion in Chris Caldwell's Prime Pages Top 5000. Sometime in 2009, over 90% of the tests handed out by PrimeGrid were numbers that have never been tested.
Since then a great deal of proth primes have been found, including over 92 mega primes!
PrimeGrid intends to continue the search indefinitely for Proth primes.
What is sieving?
Sieving is the first step to prime finding. In general, a sieve separates wanted/desired elements from unwanted material using a tool such as a mesh, net or other filtration or distillation methods. The word "sift" derives from this term. (Wikipedia - Sieve)
In PrimeGrid's case, the desired elements ultimately are prime numbers and the unwanted material are composite numbers. Our tool of choice for PPS sieve is Geoff Reynolds'/Ken Brazier's tpsieve program. It eliminates possible candidates by removing numbers that have small factors. As this process is much faster than primality testing, it is good to thoroughly sieve a data set before primality testing.
Sieving removes many candidates at the beginning. However, the deeper the sieve goes, the slower the rate of removal, till eventually sieving removes candidates at the same rate as primality testing. This is sometimes referred to as "optimal depth". Primality testing is recommended at this point.
There are many factors that determine how much time and how deep to sieve. After sieving, all the remaining candidates must be primality tested to determine their "prime" status.
About the Winter Solstice