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Distributed.net doing OGR-24 again. Soon OGR-25.

By Buck Satan in News
Sat Jul 15, 2000 at 11:46:04 PM EST
Tags: Software (all tags)
Software

distributed.net has once again started computing Optimal Golomb Rulers. You need to have the latest client (or at least 2.8009.460) to participate. This *is* an important thing for folks to be computing, as it helps the scientific community. As is noted on the dnet OGR page, "OGR's have many applications including sensor placements for X-ray crystallography and radio astronomy. Golomb rulers can also play a significant role in combinatorics, coding theory and communications."


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Distributed.net doing OGR-24 again. Soon OGR-25. | 22 comments (8 topical, 14 editorial, 0 hidden)
how about we decide to use /etc? (1.67 / 3) (#9)
by argent on Fri Jul 14, 2000 at 11:12:37 PM EST

I agree that kuro5hin needs a news post catagory. How about /etc? So far, after a week of lurking/posting, I'm liking what kuro5hin is about. So, what do you think?
cd /pub more Beer
/etc & /news (below/above?) - K5 NEEDS META!! (4.50 / 2) (#20)
by Anonymous Hero on Sun Jul 16, 2000 at 01:11:40 AM EST

And K5 really needs a meta-discussion board, so these things don't get lost in stories... And a place to ask general questions (like why doesn't forms/polls work for me, or why can't I read stories in the queue?).

So, where's a section with discussion articles on what K5 needs (MLP/news), etc?

Then all the discussion (and good ideas) can get put there...

That said, the article doesn't offer many possibilities for discussion, I mean only serious math-majors could point out new things to use the ruler for, and they'd get *published* for doing that... Implementation of this for something usefully hasn't been shown, and that'd be more: "hey cool!" rather than a discussion. (What would you use this ruler for anyhow?)

-- Ender, Duke_of_URL

[ Parent ]
Contest OGR-24 explained (4.70 / 10) (#13)
by feline on Sat Jul 15, 2000 at 02:44:55 PM EST

A golomb ruler is basicly a set of numbers where none of the 'distances' between each mark on the ruler are equal. This golomb ruler is just like a regular metric ruler, except the distances between each mark is different (which would make a rather awkward measurement tool :))

For example, a pretty easy golomb ruler set is 0, 1, 4, 9, and 11. The distance between 0 and 11 is not duplicated any where on the ruler. The distance between 1 and 4 (three) is not duplicated anywhere else on this particular ruler either, nor is the difference of 4 to 11 (note that I said 'difference,' as opposed to distance. The ruler part in 'Golomb Ruler' is just an analogy to a ruler, to make it a bit easier to understand during explanation). The point is, no where on the ruler are the distances between the marks equal.

The goal of a project such as OGR-24 (Optimal Golomb Ruler), is to find the golomb ruler with the least distance between each mark, but still to make sure that it stays golomb. The '24' in OGR-24 is the number of marks on each ruler. Obviously, this can become rather difficult to compute. Immagine how hard it would have been to even do an unoptimal 10 node golomb ruler with a pencil and paper (James Shearer maintains a list of the first 23 known optimal golomb rulers). Now, try to come up with a 24 mark optimal golomb ruler! It can get pretty intensive, as you can immagine, a perfect task for an internet based distributed computing project.
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'Hello sir, you don't look like someone who satisfies his wife.'

Re: Contest OGR-24 explained (none / 0) (#16)
by Incognegro on Sat Jul 15, 2000 at 10:27:31 PM EST

Please add your explanation of what Golomb rulers are to the article display.

Could you also say something on what kind of approaches one could use to write code for generating some Golomb rulers ?
-- I choose not to have a signature. I choose to be anonymous. I choose not to be recognizable except by my own authority. Don't you choose to be in control of yourself ?
[ Parent ]

Re: Contest OGR-24 explained (none / 0) (#18)
by feline on Sat Jul 15, 2000 at 11:45:13 PM EST

'Please add your explanation of what Golomb rulers are to the article display.'

I'm afraid that I cannot modify other peoples' stories. I was thinking about just submitting another story with, but this story's got a score of 30 already, and I don't want to be responsible for putting two stories with the exact same subject up.

As for your second question, I'm afraid that I don't know.
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'Hello sir, you don't look like someone who satisfies his wife.'
[ Parent ]

Re: Contest OGR-24 explained (none / 0) (#21)
by Inoshiro on Sun Jul 16, 2000 at 02:10:05 AM EST

I can tack on any explanation you have to the story quite easily.

--
[ イノシロ ]
[ Parent ]
Re: Contest OGR-24 explained (2.00 / 1) (#19)
by fuzzylogic on Sun Jul 16, 2000 at 12:28:44 AM EST

A short description of how the distributed.net golomb ruler search works can be found here, in the "How the OGR Search Works" section.

The page states it uses "depth-first recursive tree traversal," so it's basically a depth first search that you learn about in AI class. The search actually utilizes the best-known ruler that's on the list which feline linked to, so if during the search adding a new mark exceeds the length of that one, you know it's not the shortest since there's already one that's shorter that's known. (or something like that. Hey, it's 12:30am :)
-- logifuzic
[ Parent ]

Distributed computing over public networks (3.00 / 1) (#22)
by Pac on Sun Jul 16, 2000 at 12:47:37 PM EST

I would like to offer some thoughts about the future of distributed computing, specially over the Internet. As a background, keep in mind that I have run SETI client for a long time from machines that only went down for the required NT weekly reboot :).

I think the political weight of running a distributed application for a private enterprise will, for all practical effects, disallow this kind of effort. I will not lease my spare cycles for some unknown project that may well be the project of a new nuclear plant, the calculation of more efficient ways to clear forests or the balistc simulation of a new whale harpoon.

On the other hand, I think there are some opportunnities here for a private enterprise, but selling to business, not to individuals. If a generic client could be developed that would be easily configured to handle new kinds of calculations, a company could easily use the added computing power of all its workstations to enhance its main computing power. Things like business simulations, pay-roll processing, market simulations could be distributed across the company's LAN and run during the large idle times a typical workstation experiences.

On the Internet at large, there lots of problems, some more important than others, that could attract public attention. Distributed.net projects are usually linked to mathematical problems and cryptography, the former sometimes amusing, the latter important but not so "fancy" as to capture a large non-technical audience. SETI project is both important and fancy, but its imediate effects fall in the nothing-to-very-small range due to the problem's nature.

Things like weather simulations, medical data processing and basic science calculations may well have a good opportunity here. Who would not like to help predict hurricanes or help processing numbers that may lead to a cure for cancer? This kind of project would certanly capture the public imagination and have a fair chance of showing results in a short spam of time, feeding more media attention to it.

Evolution doesn't take prisoners


Distributed.net doing OGR-24 again. Soon OGR-25. | 22 comments (8 topical, 14 editorial, 0 hidden)
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