No it is not. While integer factorization is not known to be NPcomplete, there is no known expected polynomial time algorithm to solve it (polynomial in the number of digits (not in the magnitude of the integer). To my knowledge the best result is exp[(1+o(1))sqrt(log n)(sqrt(log log n)], where n in the number to be factorized and consequently log n is the number of digits.
"This is similar to the problem of determining whether two graphs are identical". I think these guys should read: Babai, L., Erdös, P., and Selkow, S.M. Random Graph Isomorphism. In Proceedings of SIAM J. Comput.. 1980, 628-635.
In fact graph isomorphism is a relatively easy problem, while it is not known to be in P, it is not known to be NPcomplete either and is considered to be in a class of its own between the two. Further, it is in general easy as there exist several algorithms that solve it in expected polynomial time. all this without resorting to quantum computation.
the normalized device coordinates is still a 3D space, it is just rectification that transforms the view frustum into a cube such that all rays converging to the eye become parallel to the z axis. Occlusion is handled in this space through z-buffer: each point is mapped to normalized device coordinates and then the value stored on the z-buffer at its transformed x,y coordinates is confronted with the transformed z coordinate. If the value on the z-buffer is bigger the point is drawn and the z-buffer updated, otherwise the point is occluded. The transformation I propose comes before occlusion detection and you still need two z-buffers, but you can compute transformation for each triangle only toward one eye and then transform the coordinates to those of the other eye.
nah, you are making it too complicated by thinking in world coordinates. You can transform points in normalized device coordinates (after applying the projection matrix). The transformation from one eye's coordinates to the other is just a 3D homography, so you can map a point in left eye's coordinate to one in the right eye's coordinate (assuming a symmetric frustum) by multiplying it by the matrix
where r is the location of the right plane (and -r of the left plane), f is the location of the far plane, n the location of the near plane and d is the eye displacement.
Case independence just does not work! At least not if you start adding non-latin1 characters: uppercase-lowercase correspondence is locale-dependent which means the filesystem has to kow the locale of the filename and the system must have it installed. Besides having user-locale info at the filesystem level is a clear layering violation. Windows and Mac OS are paying with huge complexity, File-lookup inefficiencies, and limited cross-sytem compatibility their bad decision to go for case-independent filenames. Especially now that the hole world is moving to Unicode.
Ahem... but most library calls themselves invoke system calls to get the job done. I doubt pthread semaphores and mutexes are implemented without some help from the system (access to shared memory, putting threads into wait queues, etc.)
True, but in the case of mutexes, library call doesn't need to invoke a syscall in the fast path: the common case is "no contention" and that can be resolved with a lock-n-set CUP intruction, the library call needs to invoke the syscall only if there is a contention, and in that case you are going to wait anyway, so no loss there!
This way you will just create cliques of people with the same views, reducing interaction to people with the same ideas and isolating yourself from any alernative view. If this is your goal why do you read comments at all?!? If you all you want is someone to agree with, just talk to yourself!
DVD does not _require_ encription, encripted DVD content requires decription. If you feed non encripted DVDs to a player it should just play it. As for region coding, I think that a DVD can be not coded, or that there is an "everywhere" code, but I am not totally sure about that...
Re:why such a fast RAMDAC?
on
Nvidia's NV20
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· Score: 1
Those 200dpi monitors have a digital connection: no need for a Digital to Analog Convertor!
A digital connection with the same bandwidth would be a lot cheaper (Fast and precise DACs are relatively expensive)!
Upload and download are different data streams at data-link (modem) level, not at the transport level: TCP is quite chatty and all those ACKs have to go back somehow. If your connection is not to the same computer the upload is going to, ACKs cannot piggyback your packets and have to be sent as stand-alone packets. These packets will have precisely 1 bit of useful information, but still use "minimum packet size" bytes. Quite wasteful!
Re:This is an incorrect definition of NP
on
Does P = NP?
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· Score: 1
No, Factoring an integer is NP Hard, NP problems are, by definition, decision problem. NP Hard problems are general problems with the property that an NP Complete problem can be transformed into it.
VAT taxes the "value added" at each step of a manufacturing/distribution process
No, VAT taxes the value added in each transformation process (where you are actually *adding* a value). VAT is paid only once through any chain of distributions.
jpeg is lossy even at 100% quality. The standard requires storing 1/4 of the Crominance and Saturation values. (they user 4x4 pixel Crominance and Saturation boxes for each 8x8 pixel luminance box)
I agree with you that the porblem is fundamentealy of user education and that if someone executes attached programs (s)he gets what (s)he deserves, but there is something you can do about scripts:
1) run them in a sandbox. It might still propagate reading your addressbook, but it will not otherwise affect your system.
2) Don't embed scripts in documents! Documents must not be trojans! Scripting capabilities are great, but keep them well separated and separable!!! Office really pisses me off in that respect: now I have to beware against data, not only programs! I need a way to distinguish them and take appropriate actions to defend myself!
Last but not least, we can try and educate: spam whoever sends you an e-mail with the funny program or a MSWord document! Let them know that that is bad netiquette and that that behaviour is what mail-trojans rely upon!
They still bias the average over the median. It might not be much, but still...
Think of a population of 3, two have intelligence value of 1 (any metric) and one has value 1.5. Now the average is 1.166666 and 66% is below that! Not by much, but it is below! What I am styatin is that the two tails are not symmetric and the net result is a median (slightly) lower than the average. Thus we have that more than 50% of the population is below average! Not by much, but below.
Actually, as other posters have already told you, half of the population is dumber than the median, not the average. The interesting thing is that MORE than half is dumber than the average Joe: the lower tail of the distribution "saturates" on 0 IQ, while there is no limit on higher than average IQs. Put it another way, with very few exceptions, noone can be dumber than mud (IQ 0) while there will be few(?) more than twice as smart as our beloved Joe!
ILOVEYOU did not use any security hole in outlook, other worms did. The VBA problem with outlook is due to the fact that outlook opens any word doc (with its vba macros), but ILOVEYOU is not a word doc, it is a VBA script. The user has to actively execute the script and that makes it its fault. I can easily send a mail with a bash script containing "rm -rf/" and named ILOVEYOU to any Linux user, if he execs it he/she gets what he/she deserves!!! Going back to outlook, having scripting cap is a great feature, the misfeature is in word's doc format: a document format should not be able to execute code!
I think in the long run it might prove less expensive for it to have been a U.S. Space Station.
Yeah, right! And make another SkyLab??? You can't beat Russian space station's reliability and with the MIR they acquired great experience with living quarters (the single most important part of a space station). Besides, last time I checked the European parts were put on time! Let's try and be less US-centric, shall we?
I am not great in Physics, but I know geometry (and in particular the geometry of the minkovsky cronotope, i.e. relativistic space-time ambient space) pretty well, and I can tell you that, although the space restriction of the metric does not add linearly, it does add up monotonically and thus the qualitative analysis still holds. You have brought up the twin paradox and that is a great example, on inertial frames each brother would expect the other to age slower than he is doing (according to each frame the other is moving to near-light speed), but when they meet again the one that went to alpha centauri and back is the one that did not age, why? What breacks the symmetry of the problem is the acceleration, the one on earth has always been on an (almost)inertial frame of reference, while the other has seen his light cones (future and past cones) deformed due to the acceleration. In his NON-INERTIAL frame light travelled at slower (faster? should check the math) than light speed, thus in his frame less time has passed (as mesured by the light clock).
I am in no way an expert, but here is how I think it works. The problem is that when you accelerate you system is not inertial anymore an special relativity does not hold. According to general relativity, in a non-inertial system (or in presence of a gravitational field, which is the same) light can, in fact be accelerated. When you catch up to the train or the train stops eighter you or the train are accelerating. Let say that the train is coming to a halt (so your ref. system is inertial), according to your system the light still travels at a constant light, but in the train ref system the light get accelerated and bends the same way it would in presence of a gravitational field pulling torwards the front (when you break you feel a force pushing you forward remember?).
1) 0 IS a number! There is a huge difference between "nothing" (in math terms the empty set) and a "something" that has a value 0! In other words {0} (the set with 0 as its only element) is very different from the empty set.
2) 0 is an even number: the definition of "even numbers" is the set E subset of Z {u in Z | u = 0 mod 2}. Is 0 Even? YES! 0%2=0!
take a stick and put one of those black holes at one end and a handle with laser emitters all around at the other end. Set the laser freq. at the proper freq. of the black hole and point them at the singularity... Tah dah!!! you made yourself a nice lightsabre!!!
Slashdot Mirror
No it is not. While integer factorization is not known to be NPcomplete, there is no known expected polynomial time algorithm to solve it (polynomial in the number of digits (not in the magnitude of the integer).
To my knowledge the best result is exp[(1+o(1))sqrt(log n)(sqrt(log log n)], where n in the number to be factorized and consequently log n is the number of digits.
"This is similar to the problem of determining whether two graphs are identical".
I think these guys should read: Babai, L., Erdös, P., and Selkow, S.M. Random Graph Isomorphism. In Proceedings of SIAM J. Comput.. 1980, 628-635.
In fact graph isomorphism is a relatively easy problem, while it is not known to be in P, it is not known to be NPcomplete either and is considered to be in a class of its own between the two. Further, it is in general easy as there exist several algorithms that solve it in expected polynomial time. all this without resorting to quantum computation.
the normalized device coordinates is still a 3D space, it is just rectification that transforms the view frustum into a cube such that all rays converging to the eye become parallel to the z axis.
Occlusion is handled in this space through z-buffer: each point is mapped to normalized device coordinates and then the value stored on the z-buffer at its transformed x,y coordinates is confronted with the transformed z coordinate. If the value on the z-buffer is bigger the point is drawn and the z-buffer updated, otherwise the point is occluded. The transformation I propose comes before occlusion detection and you still need two z-buffers, but you can compute transformation for each triangle only toward one eye and then transform the coordinates to those of the other eye.
the last entry in the first row should be d(f+n)/(2fr) ;)
nah, you are making it too complicated by thinking in world coordinates.
You can transform points in normalized device coordinates (after applying the projection matrix).
The transformation from one eye's coordinates to the other is just a 3D homography, so you can map a point in left eye's coordinate to one in the right eye's coordinate (assuming a symmetric frustum) by multiplying it by the matrix
[ 1,0,-d(f-n)/(2fr),d(f+n)/(3fr)]
[0,1,0,0]
[0,0,1,0]
[0,0,0,1]
where r is the location of the right plane (and -r of the left plane), f is the location of the far plane, n the location of the near plane and d is the eye displacement.
Case independence just does not work! At least not if you start adding non-latin1 characters: uppercase-lowercase correspondence is locale-dependent which means the filesystem has to kow the locale of the filename and the system must have it installed. Besides having user-locale info at the filesystem level is a clear layering violation. Windows and Mac OS are paying with huge complexity, File-lookup inefficiencies, and limited cross-sytem compatibility their bad decision to go for case-independent filenames. Especially now that the hole world is moving to Unicode.
True, but in the case of mutexes, library call doesn't need to invoke a syscall in the fast path: the common case is "no contention" and that can be resolved with a lock-n-set CUP intruction, the library call needs to invoke the syscall only if there is a contention, and in that case you are going to wait anyway, so no loss there!
This way you will just create cliques of people with the same views, reducing interaction to people with the same ideas and isolating yourself from any alernative view. If this is your goal why do you read comments at all?!? If you all you want is someone to agree with, just talk to yourself!
DVD does not _require_ encription, encripted DVD content requires decription. If you feed non encripted DVDs to a player it should just play it. As for region coding, I think that a DVD can be not coded, or that there is an "everywhere" code, but I am not totally sure about that...
A digital connection with the same bandwidth would be a lot cheaper (Fast and precise DACs are relatively expensive)!
Upload and download are different data streams at data-link (modem) level, not at the transport level: TCP is quite chatty and all those ACKs have to go back somehow. If your connection is not to the same computer the upload is going to, ACKs cannot piggyback your packets and have to be sent as stand-alone packets. These packets will have precisely 1 bit of useful information, but still use "minimum packet size" bytes. Quite wasteful!
No, Factoring an integer is NP Hard, NP problems are, by definition, decision problem. NP Hard problems are general problems with the property that an NP Complete problem can be transformed into it.
No, VAT taxes the value added in each transformation process (where you are actually *adding* a value). VAT is paid only once through any chain of distributions.
Talking about gertting it right... 1*1*1=1, not 3 ;-)
WRONG!
jpeg is lossy even at 100% quality. The standard requires storing 1/4 of the Crominance and Saturation values. (they user 4x4 pixel Crominance and Saturation boxes for each 8x8 pixel luminance box)
I agree with you that the porblem is fundamentealy of user education and that if someone executes attached programs (s)he gets what (s)he deserves, but there is something you can do about scripts:
1) run them in a sandbox. It might still propagate reading your addressbook, but it will not otherwise affect your system.
2) Don't embed scripts in documents! Documents must not be trojans! Scripting capabilities are great, but keep them well separated and separable!!! Office really pisses me off in that respect: now I have to beware against data, not only programs! I need a way to distinguish them and take appropriate actions to defend myself!
Last but not least, we can try and educate: spam whoever sends you an e-mail with the funny program or a MSWord document! Let them know that that is bad netiquette and that that behaviour is what mail-trojans rely upon!
They still bias the average over the median. It might not be much, but still...
Think of a population of 3, two have intelligence value of 1 (any metric) and one has value 1.5. Now the average is 1.166666 and 66% is below that! Not by much, but it is below! What I am styatin is that the two tails are not symmetric and the net result is a median (slightly) lower than the average. Thus we have that more than 50% of the population is below average! Not by much, but below.
Actually, as other posters have already told you, half of the population is dumber than the median, not the average.
The interesting thing is that MORE than half is dumber than the average Joe: the lower tail of the distribution "saturates" on 0 IQ, while there is no limit on higher than average IQs.
Put it another way, with very few exceptions, noone can be dumber than mud (IQ 0) while there will be few(?) more than twice as smart as our beloved Joe!
ILOVEYOU did not use any security hole in outlook, other worms did. The VBA problem with outlook is due to the fact that outlook opens any word doc (with its vba macros), but ILOVEYOU is not a word doc, it is a VBA script. The user has to actively execute the script and that makes it its fault. I can easily send a mail with a bash script containing "rm -rf /" and named ILOVEYOU to any Linux user, if he execs it he/she gets what he/she deserves!!! Going back to outlook, having scripting cap is a great feature, the misfeature is in word's doc format: a document format should not be able to execute code!
Yeah, right! And make another SkyLab??? You can't beat Russian space station's reliability and with the MIR they acquired great experience with living quarters (the single most important part of a space station). Besides, last time I checked the European parts were put on time! Let's try and be less US-centric, shall we?
NOT ENOUGH!!!
I am not great in Physics, but I know geometry (and in particular the geometry of the minkovsky cronotope, i.e. relativistic space-time ambient space) pretty well, and I can tell you that, although the space restriction of the metric does not add linearly, it does add up monotonically and thus the qualitative analysis still holds.
You have brought up the twin paradox and that is a great example, on inertial frames each brother would expect the other to age slower than he is doing (according to each frame the other is moving to near-light speed), but when they meet again the one that went to alpha centauri and back is the one that did not age, why? What breacks the symmetry of the problem is the acceleration, the one on earth has always been on an (almost)inertial frame of reference, while the other has seen his light cones (future and past cones) deformed due to the acceleration. In his NON-INERTIAL frame light travelled at slower (faster? should check the math) than light speed, thus in his frame less time has passed (as mesured by the light clock).
I am in no way an expert, but here is how I think it works.
The problem is that when you accelerate you system is not inertial anymore an special relativity does not hold. According to general relativity, in a non-inertial system (or in presence of a gravitational field, which is the same) light can, in fact be accelerated. When you catch up to the train or the train stops eighter you or the train are accelerating. Let say that the train is coming to a halt (so your ref. system is inertial), according to your system the light still travels at a constant light, but in the train ref system the light get accelerated and bends the same way it would in presence of a gravitational field pulling torwards the front (when you break you feel a force pushing you forward remember?).
Hope it helps
1) 0 IS a number! There is a huge difference between "nothing" (in math terms the empty set) and a "something" that has a value 0! In other words {0} (the set with 0 as its only element) is very different from the empty set.
2) 0 is an even number: the definition of "even numbers" is the set E subset of Z {u in Z | u = 0 mod 2}. Is 0 Even? YES! 0%2=0!
take a stick and put one of those black holes at one end and a handle with laser emitters all around at the other end. Set the laser freq. at the proper freq. of the black hole and point them at the singularity...
Tah dah!!! you made yourself a nice lightsabre!!!