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Rubik's Cube Now Solvable in 20 Moves
A few years ago we reported that it had been proven that Rubik's Cubes could be solved in 23 moves. Well now that number is
down to just 20. Proving it required 35 years of computer time donated by Google to get it done.
Enough with the Rubik's cube junk, someone please tell us how to unhook a bra with *1* move.
"I'm just here to regulate funkiness."
Moves 1 through 19: repeatedly hit cube with hammer
Move 20: reassemble the smashed bits into a solved cube.
Warning: Your cube may or may not remain functional through use of this solution.
I know it won't stem the tide, but this is good research. I'm sure there are a million other algorithms in the world that can benefit from this. Shortcuts they had to invent to make sure they were using minimal processing time, full understanding of how much money and time it really took to get this process done to make other projects more practical, etc etc. This sort of thinking, even if silly on its own, has a broad range of applications.
The shortest path between any two configurations (be them solved or not) on a graph of all possibilities will be no greater than 20.
Yes, you're right, we should devote all our time to getting ourselves to live longer, and none of our time to making our lives more interesting and enjoyable. That'll make a lovely world, won't it.
How about measuring that in actual computer usage? X MHz on Y cores per Z nodes over A hours? Or at least say it would have taken one X MHz processor 35 years to compute it. Computer-hours are nothing line man-hours or horse-power. At least those have good limits to their vagueness. Computer-time might as well be arthropod-lengths (are we talking dust mites or ancient giant sea-scorpions?).
Step 2 would be "Not die until step 3", I think.
They give the distance and number of positions for the cube here: http://www.cube20.org/ What I don't understand is why they have only approximate number 20 moves - from the article on the link above I understand that they solved all of the 20-moves combinations so they must know the exact number of those combinations
Don't have to, World Community Grid has already been doing cancer cure grid computing for years.
This one is complete:
http://www.worldcommunitygrid.org/research/hdc/overview.do
These two are still running:
http://www.worldcommunitygrid.org/research/hcc1/overview.do
http://www.worldcommunitygrid.org/research/hfcc/overview.do
Thank God!
And cancer? Still unsolved. I'll bet computer time could be used for that too.
It can be shown that a cure for cancer can easily be derived from a method of solving any Rubik's cube in 19 moves.
Thank God! And cancer? Still unsolved. I'll bet computer time could be used for that too. (sorry, bullsh*t like this hits very close to home for me recently. Nothing like having people dying, and then hearing how we are using resources for utter crap)
I don't think the limiting factor in cancer research is lack of computer time. If it were something so simple, getting the resources wouldn't be a problem.
Your raging is pointless.
Yes, you're right, we should devote all our time to getting ourselves to live longer, and none of our time to making our lives more interesting and enjoyable. That'll make a lovely world, won't it.
That's what the lifestyle police are pushing for.
Eat food that tastes like cardboard, run like rabbits, and take pills based on how long they'll help you live (never mind quality of life - e.g. so hormone therapy for women is out - can't have 1 more heart attack per hundered even if it makes life bearable for the other 99) and you'll live longer or at least it will feel like it.
Just because it CAN be done, doesn't mean it should!
Yes, you're right, we should devote all our time to getting ourselves to live longer, and none of our time to making our lives more interesting and enjoyable. That'll make a lovely world, won't it.
I agree completely. After watching so many people "live" well past their prime I'd much rather have a good life and a fast death.
They say a little knowledge is a dangerous thing, but it's not one half so bad as a lot of ignorance. - Terry Pratchett
Thank God! And cancer? Still unsolved. I'll bet computer time could be used for that too. (sorry, bullsh*t like this hits very close to home for me recently. Nothing like having people dying, and then hearing how we are using resources for utter crap)
Guess you should be using your spare cycles to help cure cancer. Lead by example instead of using your resources for the utter crap that is posting on slashdot!
35 years is about 300k core-hours, a standard measure of computing resources. This is a big pile of computer time, but is not unreasonable.
So how much does this cost?
A typical supercomputer, Ranger, cost $59 million to build and operate for four years. It's got about 60k cores, so $59 million delivers 240k core-years; they used 35 core-years to do this computation. Doing the division, you get $9000 of computer time -- not all that bad. Plugging in the cost numbers for another production supercomputer, Kraken, gives a slightly lower cost.
There's a movement in health research now geared at extending what they call "healthspan" rather than just "lifespan" -- not "how long does this dude keep breathing", but "how long can we keep this dude active and happy"?
Turns out that many of the things that make people live longer also make their late years healthier. My grandfather is 94 and still travels the world with his girlfriend (a spry young 75, but he'll never see her again now that she's taken up Farmville). He got prostate cancer a few years ago (and colon cancer a few decades ago), received aggressive treatment for it, and is now cancer-free and healthy.
Old does not *have* to mean feeble. Sometimes it does, of course, and that's bad; this is why we should look at healthspan rather than lifespan.
That's where you are wrong. There is a lack of resources, funding, and computers cycles. There have been cycles running for years. I know cancer researchers, and I've donated time, money, and my computer cycles
While all research could use more funding, cancer research has to be one of the best-funded research fields out there. It's either that or defense. It lacks funding like I lack funding because I can't buy a mansion.
Could you be more specific as to what those cycles were for? I'm guessing they were for protein folding, which is essential and good research but is not going to directly find a cure. If google had run all it's computers on protein folding, we'd likely be only marginally closer to a cure for cancer.
The limiting factor in cancer research is -not- computing time. A bigger one is the fact that there are many different types of cancer, and the biggest one is that it's incredibly difficult to kill millions of any one type of cell without killing a lot of other cells in a human body. For most of our history, we had no idea how to specifically kill bacterial cells in a human body. It's still an issue.
Great job though moderators, bump up misinformation. You'd rage too if you were 34 and had to deal with this shit. And watch, I'll get marked as Troll again, even though I'm not and have a great post history. Whatever.
You're also going to get modded troll because you were asking for it. If you're 34 you should have at some point learned how to calm down and not take things so seriously.
Actually, this is a much more important result than the summary claims. Until now, there was always a gap between the proved lower bound and upper bound on necessary moves. They now proved that the known lower bound (20, proved in 1995) is also an upper bound (ie. there is no position which requires 21 or more moves to solve) and thus concluded research that lasted for 30 years.
This article could very well be listed on the Slashdot main page, it has nothing to do in Idle. The algorithms that were designed during this research are nothing to laugh at and will surely advance other research fields as well.