>If the student is root they can copy >the script to another mounted filesystem >and edit it all they want.
But, at least then they can't modify the original copy, which in some interpretations is what the article poster is actually worried about. (Not my own interpretation.)
At least, they can't modify the original copy once you've use epoxy and some kind of watermark to keep them from simply replacing it with a similar looking CD.
At least, until they replace the system's CD drive with an loop device to a modified image of the CD.
As others have said, I'd claim the task as described is impossible.
What's more, there's no code in the world worth protecting that isn't worth more money than the cost of a cheap stand alone machine on which to run it.
The software version is to create a bsd jail / user mode linux system for the rooted public to use.
And, it's one that will bite the ass of anyone dumb enough to invest in hydrinos. (As it has everyone who has done so since Mills first floated ths idea way back in 1991, at which time he announced that commercial applications of his theory were, oddly enough, just a couple years off.)
So surgeons are going to talk to astronauts who are trained to operate robots who perform surgery?
Wouldn't it be easier to just train the astronauts to perform surgery themselves? Saves you the cost of developing the robot. Is there any reason to suspect that guiding a surgeon robot will require less skill than doing the cutting by hand?
Sounds to me like someone desperately trying to justify NASA funding for a worthwhile research project that doesn't have anything at all to do with the space program. (Not necessarily a bad thing - these little robots could well be the only useful thing to emerge from our latest manned space-flight flirtation.)
Imagemagick http://imagemagick.org/ will do it quickly and easily. They're tools (mogrify and convert, especially) are perfect for that sort of job, and you have complete control over every parameter of the final image, without having to navigate a maze of checkboxes.
Especially when converting from one format to another, I've found time and time again that imagemagick succeeds where other software fails.
Best prices are usually the vendors who sell to icecream trucks. At least in the towns I've lived in, there's been at least one warehouse outlet that stocks the trucks and pushcarts. They'll usually sell you pounds of dry ice for a couple bucks, in large bricks.
First of all, it's not clear that the Long Now people are planning to use atmospheric pressure variations for their clock. They point out explicitly on their website the drawback of such a system: you need close fitting moving mechanical parts, which means you need someone around with the skills and materials to replace them regularly. See http://www.longnow.org/projects/clock/principles/ for a list of what is currently being considered.
Second, if alpha does change, it's revolutionary and very exciting - but it happens on timescales of billions of years. In 10'000 years, you'd never notice it. Laboratory limits on the variation of alpha are currently something something like 1/alpha * d(alpha)/dt 2e-16/yr.
If your atomic clock frequency scales as alpha^2/h (as the cesium hyperfine transition does, to lowest order) and you suspect h is the part of alpha that changes, then you're "off" by less than a second after 10'000 years. (I put the word off in quotes because at present we've chosen to define time based on the cesium clock itself, so it you want to be pedantic about it a cesium clock is perfectly accurate and it's the gravitating objects and other clocks that are off.) At the moment, you can't actually build an atomic clock that's good to more than about 1 part in 10^15 on the ground anyway.
There's no mechanical or gravitational system that we can measure to anywhere near that accuracy. If your goal was the best accuracy possible, you'd be well advised to use an atomic clock, even if you intend to keep it running forever.
The reason Long Now isn't building an atomic clock is that you need someone around who is able and willing to maintain it in order to keep it running. They aren't the sort of thing you can stick in a mountain and expect to come back and find it still going after a few centuries of neglect. Even if you were confident that there would be a group of people with enough technical knowhow around to maintain the thing forever and some way to pay for their keep, you'd still have to create a huge stockpile of spare parts. The thing becomes a prime target for either looting or abandonment.
The Long Now project aims to build a clock that can be forgotten for a century and then repaired by someone with hand tools. That's why they clock is mechanical and corrects itself with a sundial.
>I don't want to see robots play sports. >In theory (the Jetson's universe) watching >robots play is just a case of waiting to >see who's bearings wear out sooner.
Now that you mention it, I *do* want to watch robots play sports. (But then, I can't imagine wanting to watch humans play sports. . . so perhaps I'm missing something in this discussion.)
After all, what can you hope to see in a human game? Someone throws a ball a little bit faster than usual, or someone does something dumb but not particularly surprising on the opposing team, or someone runs just a little bit faster than you expected, or someone busts a knee.
In a robot game, on the other hand, you might well show up to find the players of been radically altered since the last game. Sure, it's baseball, and it adheres to all the formal rules of baseball, but this time the batter-bot, built by everyone's favorite celebrity robot designer, has been given ten foot long spider legs and can travel at hundreds of km/hr, and it has to outrun an outfielder with rocket engines and a pnuematic baseball cannon and avoid the tendrils of a first baseman slime-mold composed of a hundred thousand cooperative gnat sized robots. Now that's a game!
Even at the pedestrian level of what could be constructed today, putting together a fully functional robotic sports team would be an awesome feat, especially if you require the players operate autonomously. They day you field a team of robotic hockey players is the day you'll get me into the stadium.
A robot audience watching a robot marching band, waiting in line at robot run concession stands to purchase artificial food. Robot cheerleaders leading the robot audience in chants. Robots programmed to do "the wave" slightly out of sequence in order to achieve a human-like ripple. Robot bookies taking cash from robot sports betters. Robot mobs violently confronting the robot fans of the opposing team outside in choreographed fights before being handcuffed and carted away by robot riot police, only to be returned to the stadium when the game is reset for the next daily cycle. Might as well add a random number generator to the play to keep things interesting.
For the final bit of absurdity, place the whole thing on an uninhabited world orbiting a distant star and leave it running.
Here's one a friend put to me a couple months ago that I quite enjoyed.
Riddle:
You step off an airplane in a strange city about which you know nothing, and you immediately hail a taxi cab. The taxi has "licensed cab #n" written on the side of it.
If your goal is to guess exactly the number of licensed taxi cabs in the city, what number should you guess?
If your goal is to guess the number of taxi cabs in the city to within plus or minus m, what number should you guess? What if you're trying to get the answer to within some fraction of the actual value?
Commentary (with no detailed spoilers, but probably not interesting until you've solved the problem already):
Within the group in which this question was posed (consisting entirely of slightly intoxicated physics grad students), we arrived at a thoroughly convincing answer in minutes, and then spent the next hour coming to the conclusion that the question is a lot more complicated than it sounds and our initial answer was incomplete.
You have to assume something about the possible distribution of numbers of cabs in the world in order to arrive at an answer. That assumption is so obvious, at least to those trained in frequentist statistics, that it's easy not to recognize that you're making it. Consider if, for example, the question had been posed on a planet on which every city was required to have exactly 1000 licensed cabs. In that case, the winning strategy will be very different from the straightforward answer. On our world, you'd really have to know a lot about the distribution of cab fleets in cities in order to answer the question properly. (At some level this is intuitive - if you step off a jumbo jet and get into taxicab #1, it's unlikely any real person would guess they'd landed in a city with a major airport but only one cab.)
>That doesn't matter. You only cancel >constant background noise, > so you're canceling based on feedback >from sound heard earlier. > That's how the headphones work too.
But there's a big difference between trying to match the phase of a signal using analog parts with an intrinsic bandwidth of MHz and trying to match the phase of a signal when you're latency is several ms at best and varies wildly depending on what the computer is doing.
If the latency were constant to within a small fraction of the period of the highest frequency you need to cancel, then you could do it. But you'll be hard pressed to get there using a multi-tasking OS on a standard laptop.
To make a super-conservative estimate: let's say you want to compensate for only 100 Hz noise and you demand only that you get the phase right to within 45 degrees. That means you need latency changes to be constant to less than 1.2 ms. That's mighty ambitious for anything but a dedicated real-time system.
One might imagine that if the noise environment changes slowly and you have a great deal of control over everything the computer is doing you might be able to pull it off. But it sure sounds like a lot more work than building it out of dedicated hardware. And the potential for screw-ups - like occasionally getting the phase wrong by more than 90 degrees and generating a positive feedback burst that deafens the user - is pretty scary. You'd have to put some thought into making the system safe.
. . . that it's much faster to write out an equation in LaTeX than using any WYSIWYG editor on earth.
If there aren't enough buttons on the keyboard for all the symbols you need, it's much easier to represent the new ones as an obvious and transparent combination of the ones you already have than it is to construct complicated schemes to generate new ones.
Until we experience a revolution in computer interface design, it's going to take at least two keys to create a not-equal-to sign. If people are going to be forced to remember a two key sequence, it's overwhelmingly easier if what they see on the screen is a literal representation of that two key sequence.
Going to special characters replaces a single translation step (representation -> function) with two translation steps (encoding -> representation -> function). If you ask me, memorizing twice as many things so that you can avoid seeing ugly NEs and \ns is just crazy.
What's more, even if you allow for special characters, there are still plenty of non-obvious representations to deal with. What's the math symbol for a conditional numerical equality as distinct from a definition, a string comparison, or a memory address comparison? Sure, you could standardize to a definition: triple equal signs, equal signs with little symbols above and below them, etc. By what's the point? If you have to learn the definition anyway, then it hasn't bought you anything over the existing schemes.
Finally, if I may be permitted to pass from serious critique into parody verging on a flame, why not go one step further:
We needn't stop with special characters. Why are we using clunky language-based schemes to represent all the other aspects of programming languages? Why haven't abstract symbolic representations for function and variable names caught on?
After all, "case variable of" isn't exactly transparent, and it isn't closely coupled to the english definitions of those words. Just think how much cooler it would look translated as "schematic symbol for a multi-throw switch, abstract geometric shape, cartoon human figure with arms held out in a 'who, me?' expression." That would make for some beautiful code!
Sorry if this is a dupe - I've tried searching the thread with likely keywords without finding it.
The most elegant puzzle I've ever heard follows. I've heard it attributed to various people, but haven't yet come across any well documented attribution.
Consider a standard 8x8 chessboard, and a set of rectangular tiles that are exactly 1x2 squares in size. It's obvious that you can cover every square on the chessboard with 32 tiles.
Now, remove the squares from two opposite corners (eg. top left, bottom right). Is it possible to cover every remaining square using 31 tiles?
(Hint: the solution can be given in one or two short sentences and requires no formal math.)
>Hmm... someone should do a statistical >study to see what numbers >(birthdates/years, phone numbers, etc...) >people are most likely to use for their >PIN's, and see if it's possible to guess >like 80% within 3 tries. I bet it is >possible.
I'm sure someone out there has done such a study. Would be interesting to see the results.
I suspect a large fraction of all pin numbers are dates within the last 50 years, and a smaller fraction are historically important dates.
If you get a few tries before being locked out, you could probably do pretty well guessing recent dates.
>IMHO, this is not about 'protecting the children', >it is about Yahoo protecting itself.
I agree.
But, if the goal is to make life difficult for adults who troll chat rooms looking to pick up teens, then there may be real some sense to it as well.
By forcing all the kids in that chat room to lie about their age, you make things a bit more difficult for such people. Now they have to actually exchange information with a person to know whether they are (well, whether they claim to be) under 18 and can't simply pick them out of a crowd.
If you're going to be carrying around an antenna anyway, is there a compelling reason not to get a cheap wireless pcmcia card and use that instead of the internal wireless hardware?
At the very least, that might be a nice way to start. If you're going to modify hardware, better to start with a $15 network card rather than your laptop. Then, if you discover that the external antenna doesn't help you much (because it's a pain to carry around, or because the places you hang out are still too far away from access points), you won't have to worry about returning the laptop to its internal antenna. And, if by some chance you screw up and break something, you'll be stuck with a broken network card rather than a wrecked laptop.
As far as finding some way to improve your reception without modifying the hardware, you're probably out of luck. Outside of building some sort of active repeater (which would be expensive, potentially illegal, and a much bigger pain to carry around than any alternative), it's hard to think of a way improve the antenna in the laptop itself.
If you want to get silly, you could carry around a large (meter size) parabolic dish and hold your laptop at the focus of it. Not very practical, but it could be fun, and is sure to lead to interesting conversations. If you can find an appropriately shaped umbrella and a few rolls of metal tape, you might be able to make a more portable version. It's possible you could even build some sort of passive reflector out of wire, if you know how the internal antenna is oriented or you're willing to jump into a lot of trial and error.
>This is extremely important, after >hurricane Andrew, there were people >who had plenty of food in their >cabinets but had nothing to eat >because they didn't have can openers.
Hmmm. People who don't have can openers, or screwdrivers, or knives, or any sharp objects at home, or any hard surfaces at which one can throw a can? Inmates on suicide watch, perhaps? Children trapped in an inflatable bounce-room at the county fair?
Don't get me wrong - packing a can opener is a really good idea. Opening cans using anything else is a pain in the neck, especially if you're hungry, cold, injured, or otherwise in the sort of state you're likely to be in after a major emergency.
But are there really stories of people going hungry because they couldn't open a tin can? Am I just naive in assuming that hungry people would find a way to get through the 1/32" sheet metal standing between them and a meal?
A hearty second on the other advice though. In a significant disaster, your cell phones and cordless phones will be useless. Land lines are better, but no guarantee. If you don't want to become a ham for some reason, at least try to get to know the hams in your neighborhood. It will come in handy when disaster strikes. In addition to the role amateur radio plays in coordinated disaster communications, local hams are a great way to get out personal messages when regular channels fail.
Rather than trying to shield an entire house, just build yourself a set of Orgone accumulators for every member of the family and spend as much time in them as possible.
The thin metal walls are sure to do as good a job attenuating 60 Hz EMF as they do re-radiating orgone energy.
You also might want to consider placing them in the left hand middle section of you home and painting them green so as to get as much Feng Shui benefit as you can while you're at it.
Seriously, there are a lot of very real environmental hazards to worry about, but this isn't one of them. So far, decades of research have turned up no reliable evidence for risk associated with low level, low frequency electromagnetic fields, and no one can come up with an even slightly plausible mechanism by which they could damage the body.
By all means, worry about what you're breathing, and the chemicals in your food and water. (And if you want to worry about things which are orders of magnitude more likely to do you in, consider how you get to work, your diet, and exercise regimen.) Don't worry about environmental EMF exposure.
If you're not in the business of distributing content, then your boss may not be impressed. But as an example of the dangers of closed source lock-in, it's hard to beat Real audio.
For a decade they've sold content distributors expensive encoding packages. They provided the only existing client to customers, and they made a big show of claiming that by using a closed, proprietary format it would make it harder for people to archive programs.
Content producers bought up their products in mass and encoded millions of hours of audio in their format.
Then without warning, Real decided to make all of their new players incompatible with their old codecs. All the time and money that went into digitizing content is now down the drain. Those who chose the real audio format to distribute their library, and believed they were singing on for a one time fee now find themselves with media that none of their customers can access and a choice between paying a huge maintenance fee to Real to continually re-encode their audio every time the folks at Real decide they want some extra revenue, or the time and expense of switching to a brand new format and re-encoding everything from source files.
Yes, I know that it's possible to install older versions of the real audio player and convince them to not interfere with eachother. And yes, I know that there are now some alternatives to play Real content, such as mplayer. But neither helps the average computer user or the companies that are trying to communicate with them.
A few minutes trying to play random samples from albums at amazon.com with the latest real player will convince you that a lot of companies got burned trusting Real.
but I've run vanilla 2.6 kernels since 2.6.5 on four different slackware installs at work and at home: a year old dell dimension P-IV box with an nvidia graphics card, an ancient dell 300 MHz P-II machine, an even more ancient 75 MHz P-I toshiba laptop, and a newish 32 bit AMD / low-end Asus motherboard / ATI graphics card pc built from parts.
Never had any hardware problems with any of them. (Although I haven't upgraded the two older machines since around 6.5 or so - and it's possible I just happened to luck out on those machines in the first place. I've certainly heard bad things about 2.6 on very old hardware.) I'm running 6.12 now happily on both the newer machines. The only real difference is that some of the devices that weren't supported in 2.4 now work great.
I did run into some weirdness getting user space alsa components to behave nicely with the stock 2.6 kernel modules somewhere around the 2.6.5 to 2.6.8, but installing the current cvs version of everything taken directly from the alsa project right over the top of both worked without a hitch every time. The last few new kernel installs have been flawless.
Udev is pretty nice once you get used to it, and leaving scsi emulation behind is a great joy. If a crash won't cause you to be killed, fired, or otherwise endangered, then it couldn't hurt to try 2.6
>Since plenty of the merchandise sold online >is already in 'the long tail' [wired.com], >an increase of sales in that segment, >might show more clearly to the record companies >two things: 1) Hits don't necessarily have the >same pulling power in online stores as in the >local store with a limited selection of 300 albums >2) Maybe selling three copies of a song at 75 >cents is better than one at $1.49?
A good point.
Five years ago my pet theory was that online music trading would bring about the end of superstar promotions. Since the most heavily promoted performers are available everywhere but less well known artists were always impossible to find even in the music swapping heyday, I hoped that record companies would end up with an incentive to recruit and gently promote countless obscure and independent artists rather than spending millions creating a few superstars. Who would buy a Madonna album when there were thousands of file swappers online sharing the same? Spending tens of hours hunting for a complete and high quality Chuck E. Weiss album online, on the other hand, was a lot less attractive.
Of course that hasn't happened. (Yet?) One can only hope this could drive them in that direction. Or if that fails, it may annoy enough people to cause a massive return to illegal file swapping - which could eventually lead to worthwhile change. Somehow, though, I wouldn't bet on it. Record companies seem to succeed no matter how they treat their customers.
On a personal level, though, I can't imagine why anyone would buy from the apple store in the first place when you can pick up a used CD for $4-$6 per album. Not only are they cheaper, but they come with the right to play them on all the computers, stereo systems, and portable devices you're ever going to own. What's more, they're totally uncompressed and easy to encode at the quality of your choice in the format of your choice. They also come with nifty artwork and lyrics. Finally, your money goes to pay other music fans and the employees of your local music store.
Of course I realize the used music business can't possible accomodate everyone, and in may ways it thrives on the high prices of new music albums. I'm not arguing it's a solution to the problems with the industry. But as an individual actor, it boggles my mind that an individual would choose an online vendor, especially one selling crippled products with outrageously restrictive licenses like apple.
I hate Microsoft as much as the next guy, but this just doesn't make sense.
What does Microsoft have to gain by crippling anti-spam regulation? They don't spam, and as far as I know they don't actively partner with those who do. Wouldn't it be in their own best interest to push for *more* aggressive anti spam tactics?
It would be naive to assume a rational basis for most business decisions, but when an otherwise publicity-savvy company steps forward to fight for something which is not only stupid but also wildly unpopular, there's got to be some explanation.
Am I the only one who finds it sort of bizarre to call Solaris a "Linux-like operating system?"
Linus' first usenet release announcement called linux "a free version of a minix-lookalike for AT-386 computers." On Tannenbaum's web site documenting the history of minix (in a response to Ken Brown's SCO nonsense), he says "I decided to write a UNIX-like system. .."
Which, I suppose, makes Solaris-10 a UNIX-like-lookalike-like operating system.
Slashdot Mirror
>If the student is root they can copy
>the script to another mounted filesystem
>and edit it all they want.
But, at least then they can't modify the original copy, which in some interpretations is what the article poster is actually worried about. (Not my own interpretation.)
At least, they can't modify the original copy once you've use epoxy and some kind of watermark to keep them from simply replacing it with a similar looking CD.
At least, until they replace the system's CD drive with an loop device to a modified image of the CD.
As others have said, I'd claim the task as described is impossible.
What's more, there's no code in the world worth protecting that isn't worth more money than the cost of a cheap stand alone machine on which to run it.
The software version is to create a bsd jail / user mode linux system for the rooted public to use.
"Knowledge isn't important."
There's a big difference.
And, it's one that will bite the ass of anyone dumb enough to invest in hydrinos. (As it has everyone who has done so since Mills first floated ths idea way back in 1991, at which time he announced that commercial applications of his theory were, oddly enough, just a couple years off.)
So surgeons are going to talk to astronauts who are trained to operate robots who perform surgery?
Wouldn't it be easier to just train the astronauts to perform surgery themselves? Saves you the cost of developing the robot. Is there any reason to suspect that guiding a surgeon robot will require less skill than doing the cutting by hand?
Sounds to me like someone desperately trying to justify NASA funding for a worthwhile research project that doesn't have anything at all to do with the space program. (Not necessarily a bad thing - these little robots could well be the only useful thing to emerge from our latest manned space-flight flirtation.)
Imagemagick http://imagemagick.org/ will do it quickly and easily. They're tools (mogrify and convert, especially) are perfect for that sort of job, and you have complete control over every parameter of the final image, without having to navigate a maze of checkboxes.
Especially when converting from one format to another, I've found time and time again that imagemagick succeeds where other software fails.
Best prices are usually the vendors who sell to icecream trucks. At least in the towns I've lived in, there's been at least one warehouse outlet that stocks the trucks and pushcarts. They'll usually sell you pounds of dry ice for a couple bucks, in large bricks.
Err.. huh?
/yr.
First of all, it's not clear that the Long Now people are planning to use atmospheric pressure variations for their clock. They point out explicitly on their website the drawback of such a system: you need close fitting moving mechanical parts, which means you need someone around with the skills and materials to replace them regularly. See http://www.longnow.org/projects/clock/principles/ for a list of what is currently being considered.
Second, if alpha does change, it's revolutionary and very exciting - but it happens on timescales of billions of years. In 10'000 years, you'd never notice it. Laboratory limits on the variation of alpha are currently something something like 1/alpha * d(alpha)/dt 2e-16
If your atomic clock frequency scales as alpha^2/h (as the cesium hyperfine transition does, to lowest order) and you suspect h is the part of alpha that changes, then you're "off" by less than a second after 10'000 years. (I put the word off in quotes because at present we've chosen to define time based on the cesium clock itself, so it you want to be pedantic about it a cesium clock is perfectly accurate and it's the gravitating objects and other clocks that are off.) At the moment, you can't actually build an atomic clock that's good to more than about 1 part in 10^15 on the ground anyway.
There's no mechanical or gravitational system that we can measure to anywhere near that accuracy. If your goal was the best accuracy possible, you'd be well advised to use an atomic clock, even if you intend to keep it running forever.
The reason Long Now isn't building an atomic clock is that you need someone around who is able and willing to maintain it in order to keep it running. They aren't the sort of thing you can stick in a mountain and expect to come back and find it still going after a few centuries of neglect. Even if you were confident that there would be a group of people with enough technical knowhow around to maintain the thing forever and some way to pay for their keep, you'd still have to create a huge stockpile of spare parts. The thing becomes a prime target for either looting or abandonment.
The Long Now project aims to build a clock that can be forgotten for a century and then repaired by someone with hand tools. That's why they clock is mechanical and corrects itself with a sundial.
>I don't want to see robots play sports.
>In theory (the Jetson's universe) watching
>robots play is just a case of waiting to
>see who's bearings wear out sooner.
Now that you mention it, I *do* want to watch robots play sports. (But then, I can't imagine wanting to watch humans play sports. . . so perhaps I'm missing something in this discussion.)
After all, what can you hope to see in a human game? Someone throws a ball a little bit faster than usual, or someone does something dumb but not particularly surprising on the opposing team, or someone runs just a little bit faster than you expected, or someone busts a knee.
In a robot game, on the other hand, you might well show up to find the players of been radically altered since the last game. Sure, it's baseball, and it adheres to all the formal rules of baseball, but this time the batter-bot, built by everyone's favorite celebrity robot designer, has been given ten foot long spider legs and can travel at hundreds of km/hr, and it has to outrun an outfielder with rocket engines and a pnuematic baseball cannon and avoid the tendrils of a first baseman slime-mold composed of a hundred thousand cooperative gnat sized robots. Now that's a game!
Even at the pedestrian level of what could be constructed today, putting together a fully functional robotic sports team would be an awesome feat, especially if you require the players operate autonomously. They day you field a team of robotic hockey players is the day you'll get me into the stadium.
Now that's a wonderful image.
A robot audience watching a robot marching band, waiting in line at robot run concession stands to purchase artificial food. Robot cheerleaders leading the robot audience in chants. Robots programmed to do "the wave" slightly out of sequence in order to achieve a human-like ripple. Robot bookies taking cash from robot sports betters. Robot mobs violently confronting the robot fans of the opposing team outside in choreographed fights before being handcuffed and carted away by robot riot police, only to be returned to the stadium when the game is reset for the next daily cycle. Might as well add a random number generator to the play to keep things interesting.
For the final bit of absurdity, place the whole thing on an uninhabited world orbiting a distant star and leave it running.
Here's one a friend put to me a couple months ago that I quite enjoyed.
Riddle:
You step off an airplane in a strange city about which you know nothing, and you immediately hail a taxi cab. The taxi has "licensed cab #n" written on the side of it.
If your goal is to guess exactly the number of licensed taxi cabs in the city, what number should you guess?
If your goal is to guess the number of taxi cabs in the city to within plus or minus m, what number should you guess? What if you're trying to get the answer to within some fraction of the actual value?
Commentary (with no detailed spoilers, but probably not interesting until you've solved the problem already):
Within the group in which this question was posed (consisting entirely of slightly intoxicated physics grad students), we arrived at a thoroughly convincing answer in minutes, and then spent the next hour coming to the conclusion that the question is a lot more complicated than it sounds and our initial answer was incomplete.
You have to assume something about the possible distribution of numbers of cabs in the world in order to arrive at an answer. That assumption is so obvious, at least to those trained in frequentist statistics, that it's easy not to recognize that you're making it. Consider if, for example, the question had been posed on a planet on which every city was required to have exactly 1000 licensed cabs. In that case, the winning strategy will be very different from the straightforward answer. On our world, you'd really have to know a lot about the distribution of cab fleets in cities in order to answer the question properly. (At some level this is intuitive - if you step off a jumbo jet and get into taxicab #1, it's unlikely any real person would guess they'd landed in a city with a major airport but only one cab.)
Good points.
You're absolutely right. Still not the easiest way to do it, by any means, but perhaps not so daunting after all.
"you're" should of course be "your," to satisfy the grammar fanatics out there.
>That doesn't matter. You only cancel
>constant background noise,
> so you're canceling based on feedback
>from sound heard earlier.
> That's how the headphones work too.
But there's a big difference between trying to match the phase of a signal using analog parts with an intrinsic bandwidth of MHz and trying to match the phase of a signal when you're latency is several ms at best and varies wildly depending on what the computer is doing.
If the latency were constant to within a small fraction of the period of the highest frequency you need to cancel, then you could do it. But you'll be hard pressed to get there using a multi-tasking OS on a standard laptop.
To make a super-conservative estimate: let's say you want to compensate for only 100 Hz noise and you demand only that you get the phase right to within 45 degrees. That means you need latency changes to be constant to less than 1.2 ms. That's mighty ambitious for anything but a dedicated real-time system.
One might imagine that if the noise environment changes slowly and you have a great deal of control over everything the computer is doing you might be able to pull it off. But it sure sounds like a lot more work than building it out of dedicated hardware. And the potential for screw-ups - like occasionally getting the phase wrong by more than 90 degrees and generating a positive feedback burst that deafens the user - is pretty scary. You'd have to put some thought into making the system safe.
. . . that it's much faster to write out an equation in LaTeX than using any WYSIWYG editor on earth.
If there aren't enough buttons on the keyboard for all the symbols you need, it's much easier to represent the new ones as an obvious and transparent combination of the ones you already have than it is to construct complicated schemes to generate new ones.
Until we experience a revolution in computer interface design, it's going to take at least two keys to create a not-equal-to sign. If people are going to be forced to remember a two key sequence, it's overwhelmingly easier if what they see on the screen is a literal representation of that two key sequence.
Going to special characters replaces a single translation step (representation -> function) with two translation steps (encoding -> representation -> function). If you ask me, memorizing twice as many things so that you can avoid seeing ugly NEs and \ns is just crazy.
What's more, even if you allow for special characters, there are still plenty of non-obvious representations to deal with. What's the math symbol for a conditional numerical equality as distinct from a definition, a string comparison, or a memory address comparison? Sure, you could standardize to a definition: triple equal signs, equal signs with little symbols above and below them, etc. By what's the point? If you have to learn the definition anyway, then it hasn't bought you anything over the existing schemes.
Finally, if I may be permitted to pass from serious critique into parody verging on a flame, why not go one step further:
We needn't stop with special characters. Why are we using clunky language-based schemes to represent all the other aspects of programming languages? Why haven't abstract symbolic representations for function and variable names caught on?
After all, "case variable of" isn't exactly transparent, and it isn't closely coupled to the english definitions of those words. Just think how much cooler it would look translated as "schematic symbol for a multi-throw switch, abstract geometric shape, cartoon human figure with arms held out in a 'who, me?' expression." That would make for some beautiful code!
Sorry if this is a dupe - I've tried searching the thread with likely keywords without finding it.
The most elegant puzzle I've ever heard follows. I've heard it attributed to various people, but haven't yet come across any well documented attribution.
Consider a standard 8x8 chessboard, and a set of rectangular tiles that are exactly 1x2 squares in size. It's obvious that you can cover every square on the chessboard with 32 tiles.
Now, remove the squares from two opposite corners (eg. top left, bottom right). Is it possible to cover every remaining square using 31 tiles?
(Hint: the solution can be given in one or two short sentences and requires no formal math.)
>Hmm... someone should do a statistical >study to see what numbers >(birthdates/years, phone numbers, etc...) >people are most likely to use for their >PIN's, and see if it's possible to guess >like 80% within 3 tries. I bet it is >possible.
I'm sure someone out there has done such a study. Would be interesting to see the results.
I suspect a large fraction of all pin numbers are dates within the last 50 years, and a smaller fraction are historically important dates.
If you get a few tries before being locked out, you could probably do pretty well guessing recent dates.
>IMHO, this is not about 'protecting the children',
>it is about Yahoo protecting itself.
I agree.
But, if the goal is to make life difficult for adults who troll chat rooms looking to pick up teens, then there may be real some sense to it as well.
By forcing all the kids in that chat room to lie about their age, you make things a bit more difficult for such people. Now they have to actually exchange information with a person to know whether they are (well, whether they claim to be) under 18 and can't simply pick them out of a crowd.
Wow. Had no idea anyone was making such a thing.
That's perfect. And, from the looks of it, it shouldn't be hard to modify it with a high gain directional antenna.
Looks like just what the topic poster needs.
If you're going to be carrying around an antenna anyway, is there a compelling reason not to get a cheap wireless pcmcia card and use that instead of the internal wireless hardware?
At the very least, that might be a nice way to start. If you're going to modify hardware, better to start with a $15 network card rather than your laptop. Then, if you discover that the external antenna doesn't help you much (because it's a pain to carry around, or because the places you hang out are still too far away from access points), you won't have to worry about returning the laptop to its internal antenna. And, if by some chance you screw up and break something, you'll be stuck with a broken network card rather than a wrecked laptop.
As far as finding some way to improve your reception without modifying the hardware, you're probably out of luck. Outside of building some sort of active repeater (which would be expensive, potentially illegal, and a much bigger pain to carry around than any alternative), it's hard to think of a way improve the antenna in the laptop itself.
If you want to get silly, you could carry around a large (meter size) parabolic dish and hold your laptop at the focus of it. Not very practical, but it could be fun, and is sure to lead to interesting conversations. If you can find an appropriately shaped umbrella and a few rolls of metal tape, you might be able to make a more portable version. It's possible you could even build some sort of passive reflector out of wire, if you know how the internal antenna is oriented or you're willing to jump into a lot of trial and error.
>This is extremely important, after
>hurricane Andrew, there were people
>who had plenty of food in their
>cabinets but had nothing to eat
>because they didn't have can openers.
Hmmm. People who don't have can openers, or screwdrivers, or knives, or any sharp objects at home, or any hard surfaces at which one can throw a can? Inmates on suicide watch, perhaps? Children trapped in an inflatable bounce-room at the county fair?
Don't get me wrong - packing a can opener is a really good idea. Opening cans using anything else is a pain in the neck, especially if you're hungry, cold, injured, or otherwise in the sort of state you're likely to be in after a major emergency.
But are there really stories of people going hungry because they couldn't open a tin can? Am I just naive in assuming that hungry people would find a way to get through the 1/32" sheet metal standing between them and a meal?
A hearty second on the other advice though. In a significant disaster, your cell phones and cordless phones will be useless. Land lines are better, but no guarantee. If you don't want to become a ham for some reason, at least try to get to know the hams in your neighborhood. It will come in handy when disaster strikes. In addition to the role amateur radio plays in coordinated disaster communications, local hams are a great way to get out personal messages when regular channels fail.
Rather than trying to shield an entire house, just build yourself a set of Orgone accumulators for every member of the family and spend as much time in them as possible.
The thin metal walls are sure to do as good a job attenuating 60 Hz EMF as they do re-radiating orgone energy.
You also might want to consider placing them in the left hand middle section of you home and painting them green so as to get as much Feng Shui benefit as you can while you're at it.
Seriously, there are a lot of very real environmental hazards to worry about, but this isn't one of them. So far, decades of research have turned up no reliable evidence for risk associated with low level, low frequency electromagnetic fields, and no one can come up with an even slightly plausible mechanism by which they could damage the body.
By all means, worry about what you're breathing, and the chemicals in your food and water. (And if you want to worry about things which are orders of magnitude more likely to do you in, consider how you get to work, your diet, and exercise regimen.) Don't worry about environmental EMF exposure.
. . .is the Real Audio format.
If you're not in the business of distributing content, then your boss may not be impressed. But as an example of the dangers of closed source lock-in, it's hard to beat Real audio.
For a decade they've sold content distributors expensive encoding packages. They provided the only existing client to customers, and they made a big show of claiming that by using a closed, proprietary format it would make it harder for people to archive programs.
Content producers bought up their products in mass and encoded millions of hours of audio in their format.
Then without warning, Real decided to make all of their new players incompatible with their old codecs. All the time and money that went into digitizing content is now down the drain. Those who chose the real audio format to distribute their library, and believed they were singing on for a one time fee now find themselves with media that none of their customers can access and a choice between paying a huge maintenance fee to Real to continually re-encode their audio every time the folks at Real decide they want some extra revenue, or the time and expense of switching to a brand new format and re-encoding everything from source files.
Yes, I know that it's possible to install older versions of the real audio player and convince them to not interfere with eachother. And yes, I know that there are now some alternatives to play Real content, such as mplayer. But neither helps the average computer user or the companies that are trying to communicate with them.
A few minutes trying to play random samples from albums at amazon.com with the latest real player will convince you that a lot of companies got burned trusting Real.
but I've run vanilla 2.6 kernels since 2.6.5 on four different slackware installs at work and at home: a year old dell dimension P-IV box with an nvidia graphics card, an ancient dell 300 MHz P-II machine, an even more ancient 75 MHz P-I toshiba laptop, and a newish 32 bit AMD / low-end Asus motherboard / ATI graphics card pc built from parts.
Never had any hardware problems with any of them. (Although I haven't upgraded the two older machines since around 6.5 or so - and it's possible I just happened to luck out on those machines in the first place. I've certainly heard bad things about 2.6 on very old hardware.) I'm running 6.12 now happily on both the newer machines. The only real difference is that some of the devices that weren't supported in 2.4 now work great.
I did run into some weirdness getting user space alsa components to behave nicely with the stock 2.6 kernel modules somewhere around the 2.6.5 to 2.6.8, but installing the current cvs version of everything taken directly from the alsa project right over the top of both worked without a hitch every time. The last few new kernel installs have been flawless.
Udev is pretty nice once you get used to it, and leaving scsi emulation behind is a great joy. If a crash won't cause you to be killed, fired, or otherwise endangered, then it couldn't hurt to try 2.6
>Since plenty of the merchandise sold online
>is already in 'the long tail' [wired.com],
>an increase of sales in that segment,
>might show more clearly to the record companies
>two things: 1) Hits don't necessarily have the
>same pulling power in online stores as in the
>local store with a limited selection of 300 albums
>2) Maybe selling three copies of a song at 75
>cents is better than one at $1.49?
A good point.
Five years ago my pet theory was that online music trading would bring about the end of superstar promotions. Since the most heavily promoted performers are available everywhere but less well known artists were always impossible to find even in the music swapping heyday, I hoped that record companies would end up with an incentive to recruit and gently promote countless obscure and independent artists rather than spending millions creating a few superstars. Who would buy a Madonna album when there were thousands of file swappers online sharing the same? Spending tens of hours hunting for a complete and high quality Chuck E. Weiss album online, on the other hand, was a lot less attractive.
Of course that hasn't happened. (Yet?) One can only hope this could drive them in that direction. Or if that fails, it may annoy enough people to cause a massive return to illegal file swapping - which could eventually lead to worthwhile change. Somehow, though, I wouldn't bet on it. Record companies seem to succeed no matter how they treat their customers.
On a personal level, though, I can't imagine why anyone would buy from the apple store in the first place when you can pick up a used CD for $4-$6 per album. Not only are they cheaper, but they come with the right to play them on all the computers, stereo systems, and portable devices you're ever going to own. What's more, they're totally uncompressed and easy to encode at the quality of your choice in the format of your choice. They also come with nifty artwork and lyrics. Finally, your money goes to pay other music fans and the employees of your local music store.
Of course I realize the used music business can't possible accomodate everyone, and in may ways it thrives on the high prices of new music albums. I'm not arguing it's a solution to the problems with the industry. But as an individual actor, it boggles my mind that an individual would choose an online vendor, especially one selling crippled products with outrageously restrictive licenses like apple.
I hate Microsoft as much as the next guy, but this just doesn't make sense.
What does Microsoft have to gain by crippling anti-spam regulation? They don't spam, and as far as I know they don't actively partner with those who do. Wouldn't it be in their own best interest to push for *more* aggressive anti spam tactics?
It would be naive to assume a rational basis for most business decisions, but when an otherwise publicity-savvy company steps forward to fight for something which is not only stupid but also wildly unpopular, there's got to be some explanation.
Am I the only one who finds it sort of bizarre to call Solaris a "Linux-like operating system?"
."
Linus' first usenet release announcement called linux "a free version of a minix-lookalike for AT-386 computers." On Tannenbaum's web site documenting the history of minix (in a response to Ken Brown's SCO nonsense), he says "I decided to write a UNIX-like system. .
Which, I suppose, makes Solaris-10 a UNIX-like-lookalike-like operating system.