Right, so we don't really need the library of congress at all then, do we? Contact Creepy Crawler and he'll put all of the information ever recorded in the world onto a single 'infinite resolution' 35mm frame...
Originally the theorem was proposed as a means of solving NP-complete problems on a quantum computer. ie. to show that for a quantum computer, P=NP. I don't think many people actually believe that, and there are no known algorithms for NP problems.
The point is, that exponential-time problems are usually not solvable, because while it is completely obvious to every man and his dog that there are simple, dumb, brute-force algorithms to do so, the running time increases exponentially (duh) with the input size; so for any such problem it doesn't take long to get a running time of the age of the universe.
Please, can we take it for granted here, on Slashdot, that "solving NP-complete problems" means solving them in polynomial time?
Interesting. I am somewhat familiar with the 'Quantum Adiabatic Theorem', but you need to remember that it is a 'theorem' in the physics sense, not mathematical. ie, there isn't a proof, and moreover, a lot of people (including me) have doubts about it.
Originally the theorem was proposed as a means of solving NP-complete problems on a quantum computer. ie. to show that for a quantum computer, P=NP. I don't think many people actually believe that, and there are no known algorithms for NP problems. That is wild enough, but it is *really* wild that Kieu is saying that it can solve the halting problem. If the adiabatic theorem really imples that the halting problem is solvable, then I think it is just a very big nail in the coffin of the 'theorem'.
Aside: I thought the Reimann Hypothesis was formally undecidable? I also don't understand how the proof of Goldbach's conjecture would work. How can a finite computer test that the theorem is true for arbitarily large numbers? A symbolic proof is maybe possible, but then where does the computation come in? I guess I should read his paper....
The actual quotation is "Drivers have always been an issue with Linux as PC users have gotten spoiled with Windows driver support". I don't see how a rational person can disagree with this.
Because it isn't really true anymore. Its increasingly common to see hardware sporting a penguin on the box, and many more manufacturers are cooperating to produce open (GPL) drivers. Not all of course, but the minority that don't is getting smaller all the time.
Why? What is your preferred term? Yankee? (I suspect that is similar to calling a german a Kraut). American? (but the USA is only a part of (North) America).
The (AC) parent is completely correct - there is a real cultural difference between the US concept of "free speech" (which I *think* is pretty much unique to the USA?) and the more 'usual' "freedom of expression".
Hence the ridiculous debates in the USA as to whether, eg, computer software is "speech" or not, or whether arresting someone for yelling "FIRE!" in a cinema impinges on their right to freedom of speech.
Take this into account, and also Germany's recent history, and I think the only conclusion is "move along, nothing to see here". Especially in the mass media, there is much more censorship in the USA anyway, especially on anything related to nudity - never mind the sex.
Interesting paper. They avoided saying that the USA is a net carbon sink though. For their 1990 data, the comparison is 1600 million tons emissions from burning fossil fuels, versus 1700 +/- 500 million tons terrestrial uptake. So it depends where the error margin falls - but I certainly agree it is pretty close.
But what is the significance? Even the authors' of that paper have no explanation as to why terrestrial uptake in the USA is so high compared with the rest of the world. It does seem strange that less than 25% of the world's forests might account for virtually all of the carbon uptake. Still, its promising in that if the exact mechanism can be determined, perhaps it can be applied elsewhere.
So do you think this absolves the USA of any responsibility to reduce carbon emissions? If so, what about the case of Australia? Second highest per-capita emissions, but with so much ocean around it to absorb the carbon (and not much carbon, in absolute figures) surely they have no responsibilities either?
Yes, that is basically the idea. I have seen it used before, but I havn't been able to find some examples on the net, it seems to be a really hard expression to search for.
In computational science and cryptography it is common to use notation O(n^x), but it doesn't mean the same thing as Big-Oh notation, it just means 'order-of-magnitude'. Its usually clear from the context what is meant: big-oh notation describes the asymptotic behaviour as a function of input size. In this context, the input size is the length of the hash and that is fixed.
It simply means that it is possible to find a collision without a brute-force scan of O(2^80) messages. Instead, because of weaknesses in the algorithm, it is only necessary to scan O(2^69) times.
WTF? Exactly where do you think these ice cores are coming from?
That any error in the original dating will appear in the new ice core too. And if the other methods have errors, this one will inherit them.
You are just repeating what I said. I don't know what you are trying to claim is the flaw here. It is equally true that if the comparison event is known extremely precisely, then so is the new measurement. A measurement is only as good as the yardstick you measure it against. This is a well-understood notion, surely?
This assumes a lot that it can't prove?
Such as?
I said:...In almost all cases its pretty obvious by looking around the area that something has caused the inversion. This occurs is on timescales of millions to hundreds of millions of years.
You said: So the two of you are agreeing on this point. Don't act so surprised.
What part of "millions to hundreds of millions of years" did you misunderstand? The relevant timescales for ice cores is hundreds of thousands of years, which is 10-1000 times smaller than the geological timescales I was referring to.
I said: Finally, error analysis is a rather basic part of any scientific method. What makes you think that ice core climatologists wouldn't do error analysis?
You said: That's more an argument from authority than anything else.
Huh? If I said "testing your web page in an actual browser is a basic part of the web design process. What makes you think that web designers would't check their pages work with a real browser?", would you interpret that too as an 'argument from authority' ?
You seem to be arguing in terms of who is and who is not an authority rather than addressing the reasons he's giving. How does error analaysis make inaccurate methods accurate?
Where did I suggest that error analysis can make inaccurate methods accurate? I never suggested any such thing. But error analysis tells you how reliable the results are, and is a relatively well understood procedure (if not always done with due care...). But the OP said Unfortunately, that data is usually discarded because "everyone knows this is one of those erroneous readings that doesn't fit the trend." This is nothing less than an accusation that the scientists who did the analysis didn't do a proper error analysis, and simply discarded data that didn't fit their conclusions. If that were true, it would be grounds for withdrawing the research from publication and sacking the scientists responsible. So, where is the evidence for that?
See my reply elsewhere on this thread. We all mis-read the report. The forests are net consumers of carbon in the USA, in that the amount of carbon absorbed by the forsts is larger than the amount of carbon released by firest fires, decaying biomass and so on.
But this doesn't consider emissions from fossil fuels at all. The net flux of carbon from the forests only accounts for 17% of the output from fossil fuels. The all-inclusive forest + fossil fuels flux is indeed around 1,200 million metric tons of emission.
I read it again, a bit more carefully. By 'net', they do not mean total emissions from all sources, they mean 'net' as in forest effects ONLY.
The most important changes in land use affecting the U.S. share of the carbon budget are those that increase or reduce forest land. Each year, a very large amount of carbon dioxide, on the order of 100 billion metric tons, is removed from the atmosphere and sequestered into biomass and soil worldwide.
So biomass and soil accounts for 100 billion metric tons of carbon per year worldwide.
At the same time, carbon is released to the atmosphere from vegetative respiration, combustion of wood in natural or purposely set forest fires or as fuel, degradation of manufactured wood products, and the natural decay of rotting vegetative detritus.
But the same biomass is also responsible for the release of carbon.
The net numerical difference, or flux, between carbon sequestration and carbon release due to natural factors can be viewed as a measure of the relative contribution of biomass to the carbon cycle.
So by 'flux' they mean the net difference between sequestration and release, due to biomass.
Annual world carbon flux is difficult to measure but is thought to be close to zero; in other words, sequestration and respiration are roughly in balance worldwide.
So, across the whole planet, carbon flux from biomass is approximately zero (as one would expect for a steady state). Note that nowhere yet has emissions from any other source been considered!
In the United States, however, the live components of forests and the wood products produced from them (including paper and wood-based construction materials) sequestered a net of approximately 111 million metric tons of carbon (407 million metric tons of carbon dioxide) in 1992, including 12 million metric tons of carbon sequestered in wood products and 15 million metric tons of carbon sequestered in landfilled wood product waste.(112) A further 127 million metric tons of carbon were believed to be sequestered in forest soils and the forest floor in 1992. For purposes of comparison, this estimated amount of sequestered carbon offset approximately 17 percent of the 1,381 million metric tons of carbon (or 5,068 million metric tons of carbon dioxide) emitted in the United States in 1992 from the burning of fossil fuels (see Chapter 2).
This contains the real information. The US forests have a positive flux of carbon. ie, the amount of carbon stored in the forest per year is larger than the amount of carbon released by the forest per year.
BUT, this is only 17% of the carbon emitted by burning fossil fuels! So the USA is most definitely NOT a net sink of carbon!
You keep a LiveCD with MD5 hashes for the current versions of all of your binaries? Have you looked at the number of entries in/bin,/sbin,/usr/bin,/usr/sbin,/usr/local/bin,/usr/local/sbin...
Have you looked at the man page of the 'find' command?
But, I don't really understand it. According to Birdsey and Heath, between 1952 and 1992, carbon stored on U.S. forest land increased by a net of 11.3 billion metric tons, an average net increase of 281 million metric tons per year, and an amount that offset approximately 25 percent of U.S. emissions of carbon for the period.
If carbon stored on forest land only accounts for 25 percent of US emissions, then how are the forests overall a sink?
I also find it confusing that the forests are projected to be sequestering carbon at an average net annual rate of 178 million metric tons between 1992 and 2040 but the total US output of carbon is over 1,400 million metric tons. Where does the other 1,200 million metric tons go?
Slashdot Mirror
Right, so we don't really need the library of congress at all then, do we? Contact Creepy Crawler and he'll put all of the information ever recorded in the world onto a single 'infinite resolution' 35mm frame...
Originally the theorem was proposed as a means of solving NP-complete problems on a quantum computer. ie. to show that for a quantum computer, P=NP. I don't think many people actually believe that, and there are no known algorithms for NP problems.
The point is, that exponential-time problems are usually not solvable, because while it is completely obvious to every man and his dog that there are simple, dumb, brute-force algorithms to do so, the running time increases exponentially (duh) with the input size; so for any such problem it doesn't take long to get a running time of the age of the universe.
Please, can we take it for granted here, on Slashdot, that "solving NP-complete problems" means solving them in polynomial time?
Originally the theorem was proposed as a means of solving NP-complete problems on a quantum computer. ie. to show that for a quantum computer, P=NP. I don't think many people actually believe that, and there are no known algorithms for NP problems. That is wild enough, but it is *really* wild that Kieu is saying that it can solve the halting problem. If the adiabatic theorem really imples that the halting problem is solvable, then I think it is just a very big nail in the coffin of the 'theorem'.
Aside: I thought the Reimann Hypothesis was formally undecidable? I also don't understand how the proof of Goldbach's conjecture would work. How can a finite computer test that the theorem is true for arbitarily large numbers? A symbolic proof is maybe possible, but then where does the computation come in? I guess I should read his paper....
Because it isn't really true anymore. Its increasingly common to see hardware sporting a penguin on the box, and many more manufacturers are cooperating to produce open (GPL) drivers. Not all of course, but the minority that don't is getting smaller all the time.
Huh? Did you even read the comment I replied to?
Wow. This statement epitomizes everything that has gone wrong with slashdot!
Why? What is your preferred term? Yankee? (I suspect that is similar to calling a german a Kraut). American? (but the USA is only a part of (North) America).
Hence the ridiculous debates in the USA as to whether, eg, computer software is "speech" or not, or whether arresting someone for yelling "FIRE!" in a cinema impinges on their right to freedom of speech.
Take this into account, and also Germany's recent history, and I think the only conclusion is "move along, nothing to see here". Especially in the mass media, there is much more censorship in the USA anyway, especially on anything related to nudity - never mind the sex.
I pretended to be a citizen of your glorious empire on more than one such occasion, and never had any problems. ;)
But what is the significance? Even the authors' of that paper have no explanation as to why terrestrial uptake in the USA is so high compared with the rest of the world. It does seem strange that less than 25% of the world's forests might account for virtually all of the carbon uptake. Still, its promising in that if the exact mechanism can be determined, perhaps it can be applied elsewhere.
So do you think this absolves the USA of any responsibility to reduce carbon emissions? If so, what about the case of Australia? Second highest per-capita emissions, but with so much ocean around it to absorb the carbon (and not much carbon, in absolute figures) surely they have no responsibilities either?
EULA's suck. Why should this do anything to change my opinon?
PS. I wonder what would have happened if the corp refused to pay up?
Huh? You mean, if the FCC loses, then thousands of geeks would instead order a tuner card with a broadcast flag?
Maybe you have a point. But with a sig like that it is not possible to take you seriously ;)
But for practical purposes, its exponentially smaller ...
Considering the vast amount of money the DoE spends on massively huge clusters, I think the clear answer here is 'yes' ;)
It will probably end up with the trademark being awarded to mame.net.
Yes, that is basically the idea. I have seen it used before, but I havn't been able to find some examples on the net, it seems to be a really hard expression to search for.
In computational science and cryptography it is common to use notation O(n^x), but it doesn't mean the same thing as Big-Oh notation, it just means 'order-of-magnitude'. Its usually clear from the context what is meant: big-oh notation describes the asymptotic behaviour as a function of input size. In this context, the input size is the length of the hash and that is fixed.
It simply means that it is possible to find a collision without a brute-force scan of O(2^80) messages. Instead, because of weaknesses in the algorithm, it is only necessary to scan O(2^69) times.
WTF? Exactly where do you think these ice cores are coming from?
That any error in the original dating will appear in the new ice core too. And if the other methods have errors, this one will inherit them.
You are just repeating what I said. I don't know what you are trying to claim is the flaw here. It is equally true that if the comparison event is known extremely precisely, then so is the new measurement. A measurement is only as good as the yardstick you measure it against. This is a well-understood notion, surely?
This assumes a lot that it can't prove?
Such as?
I said: ...In almost all cases its pretty obvious by looking around the area that something has caused the inversion. This occurs is on timescales of millions to hundreds of millions of years.
You said: So the two of you are agreeing on this point. Don't act so surprised.
What part of "millions to hundreds of millions of years" did you misunderstand? The relevant timescales for ice cores is hundreds of thousands of years, which is 10-1000 times smaller than the geological timescales I was referring to.
I said: Finally, error analysis is a rather basic part of any scientific method. What makes you think that ice core climatologists wouldn't do error analysis?
You said: That's more an argument from authority than anything else.
Huh? If I said "testing your web page in an actual browser is a basic part of the web design process. What makes you think that web designers would't check their pages work with a real browser?", would you interpret that too as an 'argument from authority' ?
You seem to be arguing in terms of who is and who is not an authority rather than addressing the reasons he's giving. How does error analaysis make inaccurate methods accurate?
Where did I suggest that error analysis can make inaccurate methods accurate? I never suggested any such thing. But error analysis tells you how reliable the results are, and is a relatively well understood procedure (if not always done with due care...). But the OP said Unfortunately, that data is usually discarded because "everyone knows this is one of those erroneous readings that doesn't fit the trend." This is nothing less than an accusation that the scientists who did the analysis didn't do a proper error analysis, and simply discarded data that didn't fit their conclusions. If that were true, it would be grounds for withdrawing the research from publication and sacking the scientists responsible. So, where is the evidence for that?
M_n refers to the Mersenne prime comprising n 1's in binary. So M_2 is 0b11 = 3 = prime.
But this doesn't consider emissions from fossil fuels at all. The net flux of carbon from the forests only accounts for 17% of the output from fossil fuels. The all-inclusive forest + fossil fuels flux is indeed around 1,200 million metric tons of emission.
The most important changes in land use affecting the U.S. share of the carbon budget are those that increase or reduce forest land. Each year, a very large amount of carbon dioxide, on the order of 100 billion metric tons, is removed from the atmosphere and sequestered into biomass and soil worldwide.
So biomass and soil accounts for 100 billion metric tons of carbon per year worldwide.
At the same time, carbon is released to the atmosphere from vegetative respiration, combustion of wood in natural or purposely set forest fires or as fuel, degradation of manufactured wood products, and the natural decay of rotting vegetative detritus.
But the same biomass is also responsible for the release of carbon.
The net numerical difference, or flux, between carbon sequestration and carbon release due to natural factors can be viewed as a measure of the relative contribution of biomass to the carbon cycle.
So by 'flux' they mean the net difference between sequestration and release, due to biomass.
Annual world carbon flux is difficult to measure but is thought to be close to zero; in other words, sequestration and respiration are roughly in balance worldwide.
So, across the whole planet, carbon flux from biomass is approximately zero (as one would expect for a steady state). Note that nowhere yet has emissions from any other source been considered!
In the United States, however, the live components of forests and the wood products produced from them (including paper and wood-based construction materials) sequestered a net of approximately 111 million metric tons of carbon (407 million metric tons of carbon dioxide) in 1992, including 12 million metric tons of carbon sequestered in wood products and 15 million metric tons of carbon sequestered in landfilled wood product waste.(112) A further 127 million metric tons of carbon were believed to be sequestered in forest soils and the forest floor in 1992. For purposes of comparison, this estimated amount of sequestered carbon offset approximately 17 percent of the 1,381 million metric tons of carbon (or 5,068 million metric tons of carbon dioxide) emitted in the United States in 1992 from the burning of fossil fuels (see Chapter 2).
This contains the real information. The US forests have a positive flux of carbon. ie, the amount of carbon stored in the forest per year is larger than the amount of carbon released by the forest per year.
BUT, this is only 17% of the carbon emitted by burning fossil fuels! So the USA is most definitely NOT a net sink of carbon!
Have you looked at the man page of the 'find' command?
But, I don't really understand it. According to Birdsey and Heath, between 1952 and 1992, carbon stored on U.S. forest land increased by a net of 11.3 billion metric tons, an average net increase of 281 million metric tons per year, and an amount that offset approximately 25 percent of U.S. emissions of carbon for the period.
If carbon stored on forest land only accounts for 25 percent of US emissions, then how are the forests overall a sink?
I also find it confusing that the forests are projected to be sequestering carbon at an average net annual rate of 178 million metric tons between 1992 and 2040 but the total US output of carbon is over 1,400 million metric tons. Where does the other 1,200 million metric tons go?
I guess I'm misunderstanding something here.