Distributed.net Finds Optimal 25-Mark Golomb Ruler

kpearson writes "Distributed.net's 8-year-old OGR-25 distributed computing project has just proven conclusively that the predicted shortest 25-mark Golomb ruler is optimal. '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 them: 12-17-10-33-19-...).' 124,387 people participated in the project and two people found the shortest ruler, one on October 10, 2007 and the other on March 24, 2008."

Comments

wtf

[Anonymous Coward]

i know we're all supposed to be nerds here, but this is way left of field. dont supposed you could have included a LITTLE more info in the summary as to what the fuck you're talking about?

Re:proved?

[martin-boundary]

Did I fail math class?

Yes. Yes, you did.

Re:proved?

[gardyloo]

Mathematics may be defined
as the subject in which we
never know what we are talking
about,nor whether what we are
saying is true.
--Bertrand Russell

so we get cheaper, better antennas?

[ClioCJS]

The Wikipedia page says One practical use of Golomb rulers is in the design of phased array radio antennas such as radio telescopes. Antennas in an [0,1,4,6] Golomb ruler configuration can often be seen at cell sites. Does this mean we can now construct larger antennas with greater sensing power, using fewer materials, due to knowing a larger optimal configuration than previously?

Re:Story

[Raenex]

why the hell is everything tagged "story"?

I have another question. What happened to the option to turn off tags?

And one more: Is there any forum to discuss Slashdot issues? Seems like the only way is to bitch off-topic in the articles.

Shouldn't have to

[ArchieBunker]

Headlines or summaries should be self explanatory.

Hello, context???

[schamberlin]

That's got to be the most incomprehensible story summary I've ever seen posted to Slashdot, and that's saying a lot. Seriously. The predicted shortest 25-mark Golomb ruler is optimal? What on earth are you talking about? How about giving us the barest minimum of a context, so we might have some tiny clue what that spew of buzzwords is getting at.

Re:Hello, context???

[Anonymous Coward]

You really can't get more specific than that. Just because you don't know what a Golomb ruler isn't doesn't make it a bad summary. A summary has to assume some understanding of the subject at hand. If a summary includes mention of a photon, for example, it doesn't necessarily require that it be defined what a photon is in the summary.

Re:Hello, context???

[Galactic Dominator]

A summary has to assume some understanding of the subject at hand. If a summary includes mention of a photon, for example, it doesn't necessarily require that it be defined what a photon is in the summary.

That's the point of the criticism. A large majority of the readers here would be familiar with a photon, but not with a Golomb ruler.

Re:Hello, context???

[glwtta]

Sure, but since there's a Wikipedia link right in the summary that does a wonderful job explaining it, this is just a simple case of RTFA.

So, to understand the summary, and therefore decide whether or not I want to RTFA, I need to RTFA? You see where that defeats the purpose of the summary?

Re:Hello, context???

[Toonol]

This is Slashdot, we're supposed to be intelligent here. This means that while we may not know what a Golomb ruler is, we should be eager to find out, and competent enough to take the simple step necessary to do so... not complain that we aren't being spoonfed gently enough (even though posting that complaint takes more effort than the required click to actually find out).

Re:Hello, context???

[glwtta]

we should be eager to find out, and competent enough to take the simple step necessary to do so

Oh get off it. It's not about being "spoonfed", it's about writing a decent summary. When mentioning a relatively obscure topic (yes, yes, all real geeks know what a Golomb ruler is, etc) it's pretty much common sense to throw in a one-sentence description (so we at least know the general context), instead of, say, a useless list of numbers. I don't need you to tell me what I'm supposed to be eager to do, thank you very much.

As far as complaining goes, given that:
- that was a bad summary
- it is the job of an editor to improve on bad summaries
- Slashdot does have editors

It is at least theoretically possible that complaining can accomplish something. Theoretically.

Re:It hasn't been proven, it has been shown.

[gardyloo]

Yes, people routinely get this wrong. They're not wrong this time.

  In this case, the distinction between "it was proven" and "it was shown" is a distinction without a difference. In math, you can "show" something within a restricted domain; for example, that a postulated solution to a given equation really is a solution, without giving a complete family of solutions. One can show it numerically, or show it analytically. Here, a restricted set of postulated solutions over the only available domain (the positive integers) was exhaustively searched for actual solutions, and the set that satisfied the postulates was also shown to be optimal (in a well-defined sense for the problem).

    This is no more a "non-proof" than the proof of the 4-color map theorem in two dimensions, which was also "shown" using an exhaustive search.

Bah, Humbug!

[Main Gauche]

There is a BIG difference between [proven and shown] as anyone within the Maths and the Sciences can tell you. I'm sorry, but people routinely get this wrong and it gets quite aggravating.

First, there is such a thing as proof by inspection. It may be considered inelegant by certain folks, but it's there nonetheless.

Second, it's just as aggravating (for those in certain fields) that computational results are not more valued. Sure, analytical results provide insight that computational results do not. But if you simply want to know the answer, why not accept a computational result?

Third, anticipating the old "how do we know the computer didn't make a mistake" comment: Theoretical proofs need to be proofread just as code does. So why not accept a computer program (and its verified output, as in the summary) as proof?

Re:proved?

[Futile Rhetoric]

Hasn't GÃdel done pretty much exactly that?

Re:Story

[Zadaz]

Is there any forum to discuss Slashdot issues? Seems like the only way is to bitch off-topic in the articles.

No, you can directly email them but of course they will only use that as ammunition to be taken out of context and savaged via the poorly conceived "Disagree Mail" "Feature".

I'd leave, but there isn't really an alternative that's better. Instead I use adblock and suck off this teat without providing benefit to the site. (Unless you include this post as "providing benefit" which is dubious since it will almost certainly get modded down.)

RC5-72

[epine]

It's worth calculating the number of gigawatt-hours of electricity is expended on these toy problems. The original goal was to make a political point: we can't assume some of these codes are out of range with present technology. Having made your point, you're just boiling water to arbitrarily make the problem another order of magnitude more expensive to crack.

When did we decide that the major problem facing planet earth was a surplus of electricity we must burn off by any available method?

Re:What will be their next project?

[steevc]

I ran OGR25 again for the last few months in hope of seeing that project complete. RC5-72 just seems pointless to me. We already know it will take decades without some radical improvement in processing power.

I've been disappointed by the lack of updates to the dnet site. Even now the projects page still says that OGR25 is active.

I've moved to Folding@home now as I hope it will have tangible benefits. My contribution is pretty minor as I don't have the hardware for GPU processing.

Precisely!

[rbarreira]

Exactly... I participated in RC5-64, but RC5-72 just seems pointless to me. It's the exact same problem, just 256 times harder.

Furthermore, these encryption challenges are not actually discovering anything. They're essentially brute-forcing a random number which another computer chose.

Contrast this with distributed computing challenges about mathematics (such as OGR-25 which is being discussed here), health or other issues where the result is something meaningful and potentially useful about the world.

Re:OK, here is a calculation

[rbarreira]

According to this page, the same PC I mentioned before uses up 40 more watts when under full load than when idling. That's about 27% of the 150 watts I mentioned before.

These figures are just ballpark numbers which give a rough idea. There are all kinds of people running these programs... Some make computer farms specifically to run them, some others don't buy new computers but leave theirs when they otherwise wouldn't, and then there's those who don't change their habits because of distributed computing. There's everything in between as well, making it very hard to estimate the real impact.