So why then is there still a debate which, I might add, is started by a physicist with a PhD from Cambridge on the facuty at Cornell? If the experiment worked, it worked, yes?
You would think that physicists should have solved simple problem like this by now. After all, how difficult can this be to prove in a fairly simple experiment on earth? If physicists are struggling with truly hard things like the quantum chromodynamic interactions inside a proton should this not be easy?
What about building a small sail, parking it in a vacuum tube and firing a somewhat powerful laser at it? If there is movement, it works. If not, then, well, no.
When NVidia brought out the Geforce 4 they had 2 series of cards: the 440 MX and Ti cards (the 4200, 4400 and 4600). The Ti cards were (and still are) pretty fast. The differenc elies mostly in the clockspeed. The MX cards, however, are pretty much the same as the previous Geforce 2/3 things with a higher clockspeed. But NVidia called them all Geforce 4 for some reason.
IS is possible to log in to an Active Directory Domain and use those credntials for Kerberos. I am not an expert on this but AFAIK Microsft uses a somewhat bastartized version of Kerberos for Active Directory. I am interested in tusing thos tickets to authenticate with Normal SSH (the Windows version from SSH Labs) from my Windows box. Is this possible?
Remember, many Internet Cafes use Internet Explorer, WHICH SAVES ALL YOUR PASSWORDS BY DEFAULT OUT OF THE BOX.
Never forget that. Remember to clear the passwords and forms before you leave.
It is possible to switch that off but in the 50 or so Internet cafes that I have been in from South Africa to PRague and Bohemia to Germany and Mexico I have only once or twice seen that that option is switched off.
NEVER forget it.
Re:Mensa is right based on Ockhams razor
on
Pure Math, Pure Joy
·
· Score: 1
Symmetry is a property of the particular representation of the number, which is this case is typgraphic, base-10 in a particular font. Even the font is pushing it.
If you
a) Write the number in binary it is not symmetric. Mind you, it is:) OK. Scratch that. b) If you use an OCR front it is not (the top part of the glyph is skew and smaller). c) If you do not write down the number but represent it in, for instance, a binary set of charges in capacitors ina dynamic RAM device I am not sure that the concept of symmetry applies at all. d) If you write it as a Maya numeral (Which would be 1 line and 3 dot on top of it) it would only be symmetrical in one axis, but so would some of the other numbers. e) Put your computer in a font which displays numbers with different glyphs and wham, no more symmetry. Try Adobe WoobBlock or something weird.
So symmetry is NOT a property of the number itself. Primeness is though.
A good example of such a program is any type checker. A specification like the following:
f:: Int -> Char
states that a function in a program takes an integer and returns a character. The Type system should prove this. The thing is, this is in theory impossible by Rice's theorem. Hoever, for a very large (and useful) amount of programs this is quite doable. However, take the following pseudoprogram:
f(x) = if 2 = 3 then return true else return 'a'
This program be rejected by any typechecker even though it does conform to the specification of its type signature. At runtime the program will, indeed, always return a charactrer. This is difficult to see at compiletime by the typechecker hence the checker will reject it since it does not conform to its internal type structural rules (for one, in most type systems both branches of an conditional must return values of the same type)
The set of correct programs that are not caught by the typechecker are called "slack". One place where slack is sometimes a program is a datastructure that contains elements of different types, this is a problem for many typecheckers.
Research into type systems (and there is a LOT of this) tries to extend the type checking algorithms so that slack is minimized while the typechecker proves more and more programs correct, but so that the checker does not become too convoluted. I personally think that the typechecker in some modern functional languages are already going too complicated, but I digress.
However, most typed languages can type almost all useful programs with few problem cases (however exacylt those cases draw the ire of the typeless programming language crowd). THe point is that the heurstic of the algorithms is good enough to cover most of the useful cases without it being universal.
If he does what he claims to have done he would need to solve the halting problem. Theorem provers can usually check theorems (this is possible) but to prove theorems them you need to solve the halting problem. There are heuristics that can do quite OK, but on a complicated thing like a C compiler and an entire OS they will choke. Most theorem provers AFAIK are more like proof assistants in that they can prove the boring drudgery but the deep "aha" steps still need to be human. However, sometimes the prover can check that the proof of the aha (human supplied) is correct.
I knowe one theorem prover proved with human help Goedel's incompleteness theorem and if they can manage that they should manage quite some deep things, but it was still a human assisted.
However, the poster's point is valid. In order for your program to work correctly all the infrastructure that runs around it, including OS/libraries/network/hardware/bytecode interpreter/compiler, mut run correctly. And your proof is not that useful if you did not prove that all these things run correctly too. At the very least, in order to prove your program correct you would need to have some formal specification of the behaviour of the calls you made to the library to USE in your proof. And those things simply do not exist.
Your program is in the end a teensy weensy part of a whole system, unless you are writing some embedded thing on bare metal (or programming a Apple II or C64 or something really simple).
Have you tried the Batik viewer of Apache? ITs a Java program and it has a shell script to use it as a standalone viewer in X. It can also convert the SVG to about anything else out there.
Also, gnome and KDE both use SVG extensively (for all their icons) so there must be SOME SVG viewer there. I know there is a SVG rendering library, so maybe someone has wrapped a viewer around it.
That would be akin to the entire Earth, with all transmissions from it, including all Tv/Radio/Cellular/Military/Naval/Commercial Comms/3D Holographic Programming (this is the Aliens transmitting, remember) switch off and take a 10 minute break at the same time. Ain't gonna happen.
Unless they had some serious planetary moment-of-silence thing going on just when we looked.
Actually, the list of military expenditures is quite surprising (and now what one expects). Hre it is, pasted from www.geographyiq.com (interesting site, that):
1. United States 276,700,000,000 $ 2. France 46,500,000,000 $ 3. Japan 40,774,300,000 $ 4. Germany 38,800,000,000 $ 5. United Kingdom 31,700,000,000 $ 6. Italy 20,200,000,000 $ 7. China 20,048,000,000 $
Chinese military percentage per percent of GDP is 1.60, which is 99th place in the world (North Korea is at the top with over 30% of the GDP, followed by Angola, Eritrea and Ethiopa. Israel is 8th).
Interestingly, Japan is higher on the list.
Now, military expenditure only (I think) accounts for state budget allocated to the military. In China, however, many, many, many factories (that manufacture anything from toys to soap to clothes) are owned by the PLA (the military) and all profits are spent on them. If this is included in the lists above, I don't know. For instance, the US military does not own toy factorys and buy weapons with the proceeds. The PLA does.
The Chinese GDP is now at 6 Trillion US$ (the US is at 10 Trillion) and its growing. Another country to start watching which will be doing fine in 10 years is India, btw.
Actually, they can't. Their ICBM fleet has nowehre the range that the Soviet/US missiles have. The Chinese nuclear weapons were developed to deter their main ex-enemy, the Soviet Union. In fact, they almost came to a nuclear war in the late 1960's over some clashes on the Amur.
The Soviets also considered a nuclear pre-emptive strike on their nuclear weapons plant before their first test.
In the meantime the PLA's missiles have not been extended in range save for a very few missiles. They do have some Submarine base missiles but that would be tracked/destroyed by the vastly superior US Navy. They only have 3 or 4 subs.
The US government's assesment of Chinese nuclear capability is classified but there are lost of info on the net. They do pack a punch but their delivery range is very limited.
Ask any frustrated new mother who sits at home with baby. The situation is similar. Raising a baby is a lot of work (and you have to be on call all the time) but there is little social contact.
Work is for many people as much a social activity as it is a financial activity. Being with coworkers who are roughly doing the same as you and working for the same goals does make a difference and being alone will driveyou crazy.
Also, the whole "discussions at the watercooler" effect tends to go away if you are not there. Those discussion are sometimes very important.
Actually, sadly, we are heading in this direction. Currently the standards are CD Audio and DVD for Video. However, new higher-density discs (DVD's and future blue-laser systems) as well as newer video codecs (think DivX) and audio codecs (MP3/Ogg) and high-definition audio streams (5.1 channel/DTS/Dolby) are about to seriously cause this "my disc doesn't fit in you player" thing again.
There are multiple standards for audio on a DVD disc. And then there is SACD (Super Audio CD) which is compatible with CD players, but now always).
And never mind DVD+-RW/RAM and God know what else. The DVD FAQ has a large compatibility matrix. Check it out and be scared.
With the the advent of blue lasers storage capacities of 25 Gigs per disc now become possible. And there a several competing disc formats to take advantage of this. To quote the DVD FAQ: "There are now at least 5 candidates for high-definition DVD:" (section 6.5).
http://www.dvddemystified.com/dvdfaq.html
Except now for physical disc formats there is also the issue of the logical encoding of media streams on the disc. I cannot remember how many times windows's media player could not find the codec. OK, fiar enough, there is load of research into videocompression going on right now (even in image compression, witness JPEG2000 which uses wavelets).
Things are going to be worse before they get better for the next 10 years or so.
Interestingly, a friend of my dad has a large collection of old (as in pre-WWII) record and wax cylinder players. Many of those things were not compatible with each other either. Standards wars raged for many years.
This was the first game I ever plqayed where there was speech. I remember getting the disks, installing it and sort of looking at the title movie. I was quite a WC1 fan, and had some interest in WC2. WC1 had the movies but not speech. It had that stupid corny mouth moving thing with subtitles and background music. So when the movie started I sort of expected that.
Then Prince Thrakath turned around and said "Guards. Leave us. How goes the war against the humans". OMG that was something. Totally unexpected. I will never forget the moment. WC2 also had very nice music.
Any my one friend still swears I was in love with Angel.
Depends on what you are attacking. If your target is a missilo silo you need to get a 100 kT warhead in within 20 m or so to destroy the silo. These things are pretty strong.
Slashdot Mirror
So why then is there still a debate which, I might add, is started by a physicist with a PhD from Cambridge on the facuty at Cornell? If the experiment worked, it worked, yes?
Again, reading the article will show that a Crooke Vane is NOT the same as a solar sail, it works in the OPPOSITE direction. Read the article.
Perhaps these idiots should go NAI themselves
You would think that physicists should have solved simple problem like this by now. After all, how difficult can this be to prove in a fairly simple experiment on earth? If physicists are struggling with truly hard things like the quantum chromodynamic interactions inside a proton should this not be easy?
What about building a small sail, parking it in a vacuum tube and firing a somewhat powerful laser at it? If there is movement, it works. If not, then, well, no.
Maybe if you actually read the article you will see that it is mentioned... And that Crooke Vanes tend to prove that Solar Sails can NOT work.
When NVidia brought out the Geforce 4 they had 2 series of cards: the 440 MX and Ti cards (the 4200, 4400 and 4600). The Ti cards were (and still are) pretty fast. The differenc elies mostly in the clockspeed. The MX cards, however, are pretty much the same as the previous Geforce 2/3 things with a higher clockspeed. But NVidia called them all Geforce 4 for some reason.
THat is a Geforce 4 MX; which is a crap video card. Due to marketing by NVidia the MX is about as fast as a Geforce 2. Buy a Ti
One place you could look for are any sites about Wearable Computers. There are a few devices in the field such as the oft mentioned Twiddler.
IS is possible to log in to an Active Directory Domain and use those credntials for Kerberos. I am not an expert on this but AFAIK Microsft uses a somewhat bastartized version of Kerberos for Active Directory. I am interested in tusing thos tickets to authenticate with Normal SSH (the Windows version from SSH Labs) from my Windows box. Is this possible?
Remember, many Internet Cafes use Internet Explorer, WHICH SAVES ALL YOUR PASSWORDS BY DEFAULT OUT OF THE BOX.
Never forget that. Remember to clear the passwords and forms before you leave.
It is possible to switch that off but in the 50 or so Internet cafes that I have been in from South Africa to PRague and Bohemia to Germany and Mexico I have only once or twice seen that that option is switched off.
NEVER forget it.
Symmetry is a property of the particular representation of the number, which is this case is typgraphic, base-10 in a particular font.
Even the font is pushing it.
If you
a) Write the number in binary it is not symmetric. Mind you, it is:) OK. Scratch that.
b) If you use an OCR front it is not (the top part of the glyph is skew and smaller).
c) If you do not write down the number but represent it in, for instance, a binary set of charges in capacitors ina dynamic RAM device I am not sure that the concept of symmetry applies at all.
d) If you write it as a Maya numeral (Which would be 1 line and 3 dot on top of it) it would only be symmetrical in one axis, but so would some of the other numbers.
e) Put your computer in a font which displays numbers with different glyphs and wham, no more symmetry. Try Adobe WoobBlock or something weird.
So symmetry is NOT a property of the number itself. Primeness is though.
Uh, forgive me, but why is this is THEOREM?
A good example of such a program is any type checker. A specification like the following:
:: Int -> Char
f
states that a function in a program takes an integer and returns a character. The Type system should prove this. The thing is, this is in theory impossible by Rice's theorem. Hoever, for a very large (and useful) amount of programs this is quite doable. However, take the following pseudoprogram:
f(x) = if 2 = 3 then return true else return 'a'
This program be rejected by any typechecker even though it does conform to the specification of its type signature. At runtime the program will, indeed, always return a charactrer. This is difficult to see at compiletime by the typechecker hence the checker will reject it since it does not conform to its internal type structural rules (for one, in most type systems both branches of an conditional must return values of the same type)
The set of correct programs that are not caught by the typechecker are called "slack". One place where slack is sometimes a program is a datastructure that contains elements of different types, this is a problem for many typecheckers.
Research into type systems (and there is a LOT of this) tries to extend the type checking algorithms so that slack is minimized while the typechecker proves more and more programs correct, but so that the checker does not become too convoluted. I personally think that the typechecker in some modern functional languages are already going too complicated, but I digress.
However, most typed languages can type almost all useful programs with few problem cases (however exacylt those cases draw the ire of the typeless programming language crowd). THe point is that the heurstic of the algorithms is good enough to cover most of the useful cases without it being universal.
If he does what he claims to have done he would need to solve the halting problem. Theorem provers can usually check theorems (this is possible) but to prove theorems them you need to solve the halting problem. There are heuristics that can do quite OK, but on a complicated thing like a C compiler and an entire OS they will choke. Most theorem provers AFAIK are more like proof assistants in that they can prove the boring drudgery but the deep "aha" steps still need to be human. However, sometimes the prover can check that the proof of the aha (human supplied) is correct.
I knowe one theorem prover proved with human help Goedel's incompleteness theorem and if they can manage that they should manage quite some deep things, but it was still a human assisted.
However, the poster's point is valid. In order for your program to work correctly all the infrastructure that runs around it, including OS/libraries/network/hardware/bytecode interpreter/compiler, mut run correctly. And your proof is not that useful if you did not prove that all these things run correctly too. At the very least, in order to prove your program correct you would need to have some formal specification of the behaviour of the calls you made to the library to USE in your proof. And those things simply do not exist.
Your program is in the end a teensy weensy part of a whole system, unless you are writing some embedded thing on bare metal (or programming a Apple II or C64 or something really simple).
The Mexico thing was in WW1, not WW2
Have you tried the Batik viewer of Apache? ITs a Java program and it has a shell script to use it as a standalone viewer in X. It can also convert the SVG to about anything else out there.
Also, gnome and KDE both use SVG extensively (for all their icons) so there must be SOME SVG viewer there. I know there is a SVG rendering library, so maybe someone has wrapped a viewer around it.
> what if the aliens took a 10 min break?
That would be akin to the entire Earth, with all transmissions from it, including all Tv/Radio/Cellular/Military/Naval/Commercial Comms/3D Holographic Programming (this is the Aliens transmitting, remember) switch off and take a 10 minute break at the same time. Ain't gonna happen.
Unless they had some serious planetary moment-of-silence thing going on just when we looked.
And what, may I ask are you going to do with an Alien? Screw it/her? Not bloody likely. This is not Startrek, you know, its Real Life!
Actually, the list of military expenditures is quite surprising (and now what one expects). Hre it is, pasted from www.geographyiq.com (interesting site, that):
1. United States 276,700,000,000 $
2. France 46,500,000,000 $
3. Japan 40,774,300,000 $
4. Germany 38,800,000,000 $
5. United Kingdom 31,700,000,000 $
6. Italy 20,200,000,000 $
7. China 20,048,000,000 $
Chinese military percentage per percent of GDP is 1.60, which is 99th place in the world (North Korea is at the top with over 30% of the GDP, followed by Angola, Eritrea and Ethiopa. Israel is 8th).
Interestingly, Japan is higher on the list.
Now, military expenditure only (I think) accounts for state budget allocated to the military. In China, however, many, many, many factories (that manufacture anything from toys to soap to clothes) are owned by the PLA (the military) and all profits are spent on them. If this is included in the lists above, I don't know. For instance, the US military does not own toy factorys and buy weapons with the proceeds. The PLA does.
The Chinese GDP is now at 6 Trillion US$ (the US is at 10 Trillion) and its growing. Another country to start watching which will be doing fine in 10 years is India, btw.
Actually, they can't. Their ICBM fleet has nowehre the range that the Soviet/US missiles have. The Chinese nuclear weapons were developed to deter their main ex-enemy, the Soviet Union. In fact, they almost came to a nuclear war in the late 1960's over some clashes on the Amur.
The Soviets also considered a nuclear pre-emptive strike on their nuclear weapons plant before their first test.
In the meantime the PLA's missiles have not been extended in range save for a very few missiles. They do have some Submarine base missiles but that would be tracked/destroyed by the vastly superior US Navy. They only have 3 or 4 subs.
The US government's assesment of Chinese nuclear capability is classified but there are lost of info on the net. They do pack a punch but their delivery range is very limited.
Ask any frustrated new mother who sits at home with baby. The situation is similar. Raising a baby is a lot of work (and you have to be on call all the time) but there is little social contact.
Work is for many people as much a social activity as it is a financial activity. Being with coworkers who are roughly doing the same as you and working for the same goals does make a difference and being alone will driveyou crazy.
Also, the whole "discussions at the watercooler" effect tends to go away if you are not there. Those discussion are sometimes very important.
Actually, sadly, we are heading in this direction. Currently the standards are CD Audio and DVD for Video. However, new higher-density discs (DVD's and future blue-laser systems) as well as newer video codecs (think DivX) and audio codecs (MP3/Ogg) and high-definition audio streams (5.1 channel/DTS/Dolby) are about to seriously cause this "my disc doesn't fit in you player" thing again.
There are multiple standards for audio on a DVD disc. And then there is SACD (Super Audio CD) which is compatible with CD players, but now always).
And never mind DVD+-RW/RAM and God know what else. The DVD FAQ has a large compatibility matrix. Check it out and be scared.
With the the advent of blue lasers storage capacities of 25 Gigs per disc now become possible. And there a several competing disc formats to take advantage of this. To quote the DVD FAQ: "There are now at least 5 candidates for high-definition DVD:" (section 6.5).
http://www.dvddemystified.com/dvdfaq.html
Except now for physical disc formats there is also the issue of the logical encoding of media streams on the disc. I cannot remember how many times windows's media player could not find the codec.
OK, fiar enough, there is load of research into videocompression going on right now (even in image compression, witness JPEG2000 which uses wavelets).
Things are going to be worse before they get better for the next 10 years or so.
Interestingly, a friend of my dad has a large collection of old (as in pre-WWII) record and wax cylinder players. Many of those things were not compatible with each other either. Standards wars raged for many years.
To paraphrase Dogbert: "Next week a doctor with a flashlight will come ans show us where Larry gets his ideas".
Oh yes.
This was the first game I ever plqayed where there was speech. I remember getting the disks, installing it and sort of looking at the title movie. I was quite a WC1 fan, and had some interest in WC2. WC1 had the movies but not speech. It had that stupid corny mouth moving thing with subtitles and background music. So when the movie started I sort of expected that.
Then Prince Thrakath turned around and said "Guards. Leave us. How goes the war against the humans". OMG that was something. Totally unexpected. I will never forget the moment. WC2 also had very nice music.
Any my one friend still swears I was in love with Angel.
Depends on what you are attacking. If your target is a missilo silo you need to get a 100 kT warhead in within 20 m or so to destroy the silo. These things are pretty strong.