Seee Wolfram, New Kind of Science. p. 1138. The whole idea of undecidibility is that all types of undecidability are equivilent. If you could figure out one, you'd have a solution of the halting problem.
The three body system not having a general explicit solution has little to do with undecidability. I don't have the book at hand, but the properties of three body newtonian system have nothing to with undecidability.
Instead, iterative solutions are used: given the current masses, positions, and velocities of the objects involved, figure out where they'll be a short time from now. Lather, rinse, repeat. The problem with this is that over long timespans (tens of millions of years), errors build up.
Almost so. Wether errors build up not depend on how chaotic the system is. For example the planetary system is not that chaotic at all (well, iirc, the Saturn moon Hyperion is on chaotic orbital) making it relatively easy to calculate positions even over rather lengthy time spans.
Take the three body newton for example (http://spanky.triumf.ca/www/fractint/newt_basin_t ype.html), only the colorful borders have areas that are hard to predict over time, the other areas coverge to stabile results.
In this case, it seems that it may be much more easy than the designers had hoped to break the second condition. This tends to mean that 3 is easier as well, which has ramifications for security protocols.
No, weak collisions (your condition 2) is not the same as strong collisions (your condition 3). Or to be more precise, in general case ability to produce weak collisions does not say anything about the strong collision resistance of a hash function. The technique used may (or may not, in this case the article doesn't really say about that) also reduce the strong collision resistance a bit, but luckily there's quite a bit of difference between 2^N and 2^(N/2)
I would just like to mention that one of the biggest problems of it becoming feasible to find a collision in MD5 is that a lot of routers use MD5 to authenticate routing updates with one another. If a hash is sniffed and the password is cracked then it becomes a trivial matter to inject bad routing updates and crash large networks especially if the inter-ISP BGP links are cracked. Its not quite as simple as I put it here but it is possible.
But that would require MD5 being broken all the way to strong collisions, right?
What they so far have is just a weak collision with a known-to-be-broken SHA-0. A
I have been expecting the MD5 crack for a while, it just isn't a secure hash anymore.
Care to elaborate on that a bit?
Being able to produce a weak collisions with SHA-0 is not really a "yet another end of cryptography as we know it". Almost all uses for MD5 and SHA-1 only require them to be strong collision resistant.
Moreover, I wouldn't jump the gun based on rumours. SHA-0 was known to be broken, like you already said, hence we have SHA-1 and MD5 has been around quite a while and has been studied quite a bit.
I see that I forgot the birthday paradox, which means that brute forcing a hash is much closer to a 2 ^ 80 problem.
That applies for weak collisions only, which I am assuming that they are talking about.
However, almost all "practical" (attack) uses needs strong collisions, for which the complexity indeed is about 2^160.
(The artice doesn't explicitly say it, but it should be obvious enough that it's a weak collision. Had they found a 2^51 attack for strong collisions there'd tons more fuss about it)
People who don't like team activities, but aren't actually antisocial (they aren't the same thing at all) are sometimes actually the best team players.
Care to elaborate on that a bit?
Consider it a corollary to Plato's observation that people who want to rule aren't qualified to do so.
And I say that's a misquote or Plato was being intentionally provocative. Either Plato meant or intentionally failed to say something along the lines "people that wind up in ruling positions do so because of their inherent desire to rule may not be the most qualified for the task". That might stand, but once it's stated along those lines it seems almost trivial. The simple idea there is that those people that have enough desire to be something, in this case in a position with power, enough to do some extra work just to reach that position tend do reach that position more often than those that might be more qualified to do so and yet lack the will to do so.
My argument is that, the will to rule does not imply the lack of qualification to do so, but instead the will to rule more often results in a ruling position than a mere qualification to rule.
It's like some of the twits that I sometimes hear winding up as lead designers and software architects. It would be harsh to say it's because of their lack of skills, when it's obvious that it's due to their desire to get into that position. And vice versa, in my case my undoing is my desire to just code and avoid having to deal with those inexperienced know-nothing idiots.
(I'm a bit drunk, so take all this with a grain of salt)
I believe Moulin rouge is one of those very movies.
You still don't get it. Here's another clue-by-4. The point is to find a movie that the most of the people hate the most. Not the movie _you_ dislike the most.
Regardless of how much you hate Moulin Rouge you must have noticed that quite a few people, myself not included however, actually did like it, enough for it to never qualify as the worst movie ever.
Moreover, I'm dead certain it wasn't the worst movie you've seen, unless you seen only a few dozen movies. It wasn't for me eiher, there was absolutely nothing for me. But hell, I'm first to admit that there are far more agonizing movies out there that are virtually meant for no one.
The human body constantly generates an approximate 200 watts. In case anyone's wondering, that's about 0.26 horsepower, and that's assuming that you can apply the full 200 watts of your energy. It's fun to see them try, but the physics say that the energy just isn't there.
That's not entirely accurate. I think the 200 watts is an approximation of the heat we emit in room temperatures. That's not the only source of power we have. We can also, for example, pedal.
Considering that we can run uphill fairly fast, the physics indeed says the power to overcome gravity most certainly is there, atleast for short periods of time. It's another question entirely wether we have the power to lift ourselves and the helicopter machinery using that technique. It will mostly depend on the efficiency vs the weight of the machinery.
The hell it is. 1 is not even a number in base 0. Not that base 0 makes any sense, but when someone mods your post "interesting" rather than "funny" that someone is way off.
Seriously, I'm not trying to start a flame war here. This is coming from a really long term zsh user because back when I was just starting unix and linux a fellow bearded unix guru told me something along the lines "go with zsh, it's the best" (thas was about -95). And I've never looked back, but now seing bash being the default shell in most distros I've began to wonder what's going on. Perhaps over the years bash overtook zsh or there are some hidden qualities in bash that I don't know about.
Anyone with some insight on _both_ shells would be greatly appreciated.
>> Distributed computing has its uses, but remeber: the public will only be willing to help you as long as they feel like they're contributing to something worthwhile.
> Uh, I'm not sure what this has to do with the TeraGrid . . . The TeraGrid is a distributed computing system . . . but it does not use the "public's" computers.
Oh, the header was "TeraGrid v. Distributed Computing" and the entry ended in a phrase "While the list of supercomputer sites and peak power is growing how is the world of Distributed Computing faring?". And you thought the earlier poster was off mark...:)
"but I figure some quality time with your friends and family might just be long overdue!"
I noticed the "503 service unavailable" last night 5:37 am right before I was about to crash on our office couch. Had I known there'd been some quality time coming up I probably would've stayed home in the first place...
Most people likely shouldn't use NVidia's OpenGL headers anyway. There are cases where I suppose it's easier to use them though (new extensions, et cetera).
That's just rubbish. Ofcourse you need them.
It's deffinitely not a good idea to use the mesa headers that so many people have in/usr/include/GL with the nvidia driver.
I'm an admin, I can read anyones mail at any time. Hell, I could fork a copy of everybody's incoming mail to me if I want and noone would know.
Do I do it? No. Why? I respect people's privacy, and I expect others to do the same.
Shees, that's hardly the point. I can walk up the street and smash in the window of the grocery store with ease, but it would be illegal. As should be reading other people's emails.
>> Although it may sound counterintuitive, it can (and usually does, unless you have obscene amounts of RAM) actually improve performance.
> Which begs the question: How much RAM constitutes an obscene amount? And if your RAM complement is obscene, won't the overhead of swapping cut into your performance?
You're not getting it, are you. Obscene is naturally the normal RAM you need to run your apps plus the same amount as your hd, because at that point you can cache everything and swapping even the totally unused pages will not result in performance boosts.
The point is that even if you have few gigs RAM even in those cases it makes sense to swap out some pages that haven't been used for a long time. Because that always yields more free memory to be used as page cache.
What the confusion here is mostly about is that people mix page evictions with swap-outs.
MO (mobile originating) SMS maxes out at about 300 messages/hour.
Really? That's some 13 bytes of payload per second. I don't care what the framing is or what encryption layers there are, but to have a system such as that working in 200X is... er... I don't have words to describe that.
Why was that modded funny? It's true! When I was there, any self-respecting group used SLM (Source Library Manager), aka "Slime". Only a few random groups in consumer division used VSS.
"any self-respecting group" working for Microsoft? Oh please... any one of my hot chick slaves knows that's just hot air.;-)
Of course you could just have the software randomize the location of the numbers each time.
I came across this type of device when entering a bank building. You had to enter a 6-digit code into a keypad to unlock the door. Each key was a tiny LCD display and the location of each digit was randomized for each use.
That's just absolutely silly. Even an ordinary complex enough code or password is by far easier to get by simply asking it from the person who knows it. Perhaps mere "please" won't do it, but try explaining you know where his kids go to kindergarten and know a few things about smashed knee-caps and you'll make a lot more convincing query.
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Seee Wolfram, New Kind of Science. p. 1138. The whole idea of undecidibility is that all types of undecidability are equivilent. If you could figure out one, you'd have a solution of the halting problem.
The three body system not having a general explicit solution has little to do with undecidability. I don't have the book at hand, but the properties of three body newtonian system have nothing to with undecidability.
Instead, iterative solutions are used: given the current masses, positions, and velocities of the objects involved, figure out where they'll be a short time from now. Lather, rinse, repeat. The problem with this is that over long timespans (tens of millions of years), errors build up.
t ype.html), only the colorful borders have areas that are hard to predict over time, the other areas coverge to stabile results.
Almost so. Wether errors build up not depend on how chaotic the system is. For example the planetary system is not that chaotic at all (well, iirc, the Saturn moon Hyperion is on chaotic orbital) making it relatively easy to calculate positions even over rather lengthy time spans.
Take the three body newton for example (http://spanky.triumf.ca/www/fractint/newt_basin_
sums up the gpl/eula discussion quite nicely
In this case, it seems that it may be much more easy than the designers had hoped to break the second condition. This tends to mean that 3 is easier as well, which has ramifications for security protocols.
No, weak collisions (your condition 2) is not the same as strong collisions (your condition 3). Or to be more precise, in general case ability to produce weak collisions does not say anything about the strong collision resistance of a hash function. The technique used may (or may not, in this case the article doesn't really say about that) also reduce the strong collision resistance a bit, but luckily there's quite a bit of difference between 2^N and 2^(N/2)
>> Trying to find two inputs that produce the same output should ideally take at least 2^(N-1) steps.
> Shouldn't that be 2^(N/2)?
Yes.
Trying to find and input that produces the same
output as some predermined input did is 2^(N-1)
I would just like to mention that one of the biggest problems of it becoming feasible to find a collision in MD5 is that a lot of routers use MD5 to authenticate routing updates with one another. If a hash is sniffed and the password is cracked then it becomes a trivial matter to inject bad routing updates and crash large networks especially if the inter-ISP BGP links are cracked. Its not quite as simple as I put it here but it is possible.
But that would require MD5 being broken all the way to strong collisions, right?
What they so far have is just a weak collision with a known-to-be-broken SHA-0. A
I have been expecting the MD5 crack for a while, it just isn't a secure hash anymore.
Care to elaborate on that a bit?
Being able to produce a weak collisions with SHA-0 is not really a "yet another end of cryptography as we know it". Almost all uses for MD5 and SHA-1 only require them to be strong collision resistant.
Moreover, I wouldn't jump the gun based on rumours. SHA-0 was known to be broken, like you already said, hence we have SHA-1 and MD5 has been around quite a while and has been studied quite a bit.
I see that I forgot the birthday paradox, which means that brute forcing a hash is much closer to a 2 ^ 80 problem.
That applies for weak collisions only, which I am assuming that they are talking about.
However, almost all "practical" (attack) uses needs strong collisions, for which the complexity indeed is about 2^160.
(The artice doesn't explicitly say it, but it should be obvious enough that it's a weak collision. Had they found a 2^51 attack for strong collisions there'd tons more fuss about it)
You're just using a known plaintext attack. Nothing impressive about that at all.
It's still by far the best form of attacks. Even this case shows it.
People who don't like team activities, but aren't actually antisocial (they aren't the same thing at all) are sometimes actually the best team players.
Care to elaborate on that a bit?
Consider it a corollary to Plato's observation that people who want to rule aren't qualified to do so.
And I say that's a misquote or Plato was being intentionally provocative. Either Plato meant or intentionally failed to say something along the lines "people that wind up in ruling positions do so because of their inherent desire to rule may not be the most qualified for the task". That might stand, but once it's stated along those lines it seems almost trivial. The simple idea there is that those people that have enough desire to be something, in this case in a position with power, enough to do some extra work just to reach that position tend do reach that position more often than those that might be more qualified to do so and yet lack the will to do so.
My argument is that, the will to rule does not imply the lack of qualification to do so, but instead the will to rule more often results in a ruling position than a mere qualification to rule.
It's like some of the twits that I sometimes hear winding up as lead designers and software architects. It would be harsh to say it's because of their lack of skills, when it's obvious that it's due to their desire to get into that position. And vice versa, in my case my undoing is my desire to just code and avoid having to deal with those inexperienced know-nothing idiots.
(I'm a bit drunk, so take all this with a grain of salt)
Now, which part of the "as a mac user" you did not understand?
No, wait, I see, you're the pc user you're refering to, right?
I believe Moulin rouge is one of those very movies.
You still don't get it. Here's another clue-by-4. The point is to find a movie that the most of the people hate the most. Not the movie _you_ dislike the most.
Regardless of how much you hate Moulin Rouge you must have noticed that quite a few people, myself not included however, actually did like it, enough for it to never qualify as the worst movie ever.
Moreover, I'm dead certain it wasn't the worst movie you've seen, unless you seen only a few dozen movies. It wasn't for me eiher, there was absolutely nothing for me. But hell, I'm first to admit that there are far more agonizing movies out there that are virtually meant for no one.
The human body constantly generates an approximate 200 watts. In case anyone's wondering, that's about 0.26 horsepower, and that's assuming that you can apply the full 200 watts of your energy. It's fun to see them try, but the physics say that the energy just isn't there.
That's not entirely accurate. I think the 200 watts is an approximation of the heat we emit in room temperatures. That's not the only source of power we have. We can also, for example, pedal.
Considering that we can run uphill fairly fast, the physics indeed says the power to overcome gravity most certainly is there, atleast for short periods of time. It's another question entirely wether we have the power to lift ourselves and the helicopter machinery using that technique. It will mostly depend on the efficiency vs the weight of the machinery.
0 in base 0 is 1
The hell it is. 1 is not even a number in base 0. Not that base 0 makes any sense, but when someone mods your post "interesting" rather than "funny" that someone is way off.
What we really need is attractive women into computer science.
What is so hot about bash, e.g. compared to zsh?
Seriously, I'm not trying to start a flame war here. This is coming from a really long term zsh user because back when I was just starting unix and linux a fellow bearded unix guru told me something along the lines "go with zsh, it's the best" (thas was about -95). And I've never looked back, but now seing bash being the default shell in most distros I've began to wonder what's going on. Perhaps over the years bash overtook zsh or there are some hidden qualities in bash that I don't know about.
Anyone with some insight on _both_ shells would be greatly appreciated.
That's called a troll where I come from. And there's no need to feed it just because few moderators were so easily fooled.
>> Distributed computing has its uses, but remeber: the public will only be willing to help you as long as they feel like they're contributing to something worthwhile.
:)
> Uh, I'm not sure what this has to do with the TeraGrid . . . The TeraGrid is a distributed computing system . . . but it does not use the "public's" computers.
Oh, the header was "TeraGrid v. Distributed Computing" and the entry ended in a phrase "While the list of supercomputer sites and peak power is growing how is the world of Distributed Computing faring?". And you thought the earlier poster was off mark...
"but I figure some quality time with your friends and family might just be long overdue!"
I noticed the "503 service unavailable" last night 5:37 am right before I was about to crash on our office couch. Had I known there'd been some quality time coming up I probably would've stayed home in the first place...
Most people likely shouldn't use NVidia's OpenGL headers anyway. There are cases where I suppose it's easier to use them though (new extensions, et cetera).
/usr/include/GL with the nvidia driver.
That's just rubbish. Ofcourse you need them.
It's deffinitely not a good idea to use the mesa headers that so many people have in
I'm an admin, I can read anyones mail at any time. Hell, I could fork a copy of everybody's incoming mail to me if I want and noone would know.
Do I do it? No. Why? I respect people's privacy, and I expect others to do the same.
Shees, that's hardly the point. I can walk up the street and smash in the window of the grocery store with ease, but it would be illegal. As should be reading other people's emails.
>> Although it may sound counterintuitive, it can (and usually does, unless you have obscene amounts of RAM) actually improve performance.
> Which begs the question: How much RAM constitutes an obscene amount? And if your RAM complement is obscene, won't the overhead of swapping cut into your performance?
You're not getting it, are you. Obscene is naturally the normal RAM you need to run your apps plus the same amount as your hd, because at that point you can cache everything and swapping even the totally unused pages will not result in performance boosts.
The point is that even if you have few gigs RAM even in those cases it makes sense to swap out some pages that haven't been used for a long time. Because that always yields more free memory to be used as page cache.
What the confusion here is mostly about is that people mix page evictions with swap-outs.
MO (mobile originating) SMS maxes out at about 300 messages/hour.
... er ... I don't have words to describe that.
Really?
That's some 13 bytes of payload per second. I don't care what the framing is or what encryption layers there are, but to have a system such as that working in 200X is
Why was that modded funny? It's true! When I was there, any self-respecting group used SLM (Source Library Manager), aka "Slime". Only a few random groups in consumer division used VSS.
;-)
"any self-respecting group" working for Microsoft? Oh please... any one of my hot chick slaves knows that's just hot air.
Of course you could just have the software randomize the location of the numbers each time.
I came across this type of device when entering a bank building. You had to enter a 6-digit code into a keypad to unlock the door. Each key was a tiny LCD display and the location of each digit was randomized for each use.
That's just absolutely silly. Even an ordinary complex enough code or password is by far easier to get by simply asking it from the person who knows it. Perhaps mere "please" won't do it, but try explaining you know where his kids go to kindergarten and know a few things about smashed knee-caps and you'll make a lot more convincing query.