distributed.net is proud to announce the completion of OGR-25!
A little over eight years ago, distributed.net users undertook the
search for the optimal 25 mark Golomb Ruler. This year sees the
successful conclusion of that effort. We have proven conclusively by
the exhaustive search of all possible rulers that the previously
predicted 25-mark ruler is indeed the most optimal one.
The total length of the ruler is 480, with marks at positions: 0 12 29
39 72 91 146 157 160 161 166 191 207 214 258 290 316 354 372 394 396
431 459 467 480. (This ruler may alternatively be expressed in terms
of the distance between those positions, which is how dnetc displays
This shortest ruler was found by two independent computers. The
initial report was received on October 10th, 2007 and a second,
matching result was returned on March 24th, 2008. However it was not
until the final stub was returned and verified that we could rule out
the possibility of a still-shorter ruler. This final stub was returned
on October 24th, 2008 drawing to a close the complete search of all
possible stubs. Due to the nature of an exhaustive search,
distributed.net users have also proven that the above solution is
unique (the ruler's mirror notwithstanding).
To celebrate the successful end of yet another distributed.net project
all our contributors are invited for a drink...when we find a place
large enough to host the 124,387 people that participated in this
particular distributed effort.
As previously mentioned, a successful match of the shortest ruler was
found by two independent computers. We'll be sending those two users
some free distributed.net swag and shirts for their noteworthy
contributions to the project. We'll also be sending some swag to the
user that submitted that last confirmed stub. (At the time of writing,
we had not yet received permission from those three users regarding
the publication of their identities.)
Thank you all and keep those computers busy!