I have to strongly disagree. MTW's Gravitation is not too hard for a mathematician to start with; if anything it is too simplistic. Mathematicians are already well familiar with analysis on manifolds and the explanations of mathematical topics found in Gravitation are not really rigorous enough to be helpful. They tend to confuse more than help.
Remember that these are supposed to be recommendations for a PhD student in math. Books that are too hard for those with an engineering/physics background to start with might very well be phrased in rigorous language that a mathematician would find most helpful.
Since I've RTFA a little (I know, I know, this is slashdot), and IAAM (mathematician) allow me to try to answer.
Whether a deck of cards is "random" or not is a subtle (and somewhat meaningless question). Afterall, the deck might follow a pattern but if I don't know the pattern then it appears random to me. In fact, this is exactly how decks of cards work: you've assigned each card with a number from 1 to 52, and you deal the cards by picking the card that's assigned number 1 first, number 2 second, etc. If I don't know how the numbers are assigned, then I can't tell what's coming next so it looks random. On the other hand, if I know what order you've put the cards in, then nothing is a surprise.
Instead of considering whether a deck is "random" or not, we're more interested in how well one can predict what the order of the cards are: either without seeing any of the cards, or after seeing the first few deals. For instance, if I know that you only order your decks in increasing order of rank with the suits randomly ordered, then seeing that the first deal is an Ace of Hearts tells me what the next 12 cards must be. All because I know how you like to order your cards.
This example, of course, never happens. But if instead of being certain about how you order things, what if I knew that you were more likely to order in a certain way? What if you ordered them as above 50% of the time, and the other 50% you riffle shuffled them? Then seeing an Ace of Hearts on the first deal doesn't make me certain about what's coming next, but I have a pretty good idea. Seeing a Two of Hearts re-affirms my hunch, but I still can't be completely certain.
This still isn't quite a real-life example, but it's getting close. If we know that the person shuffling favors certain orders over other, then we can predict what's coming next with better than chance accuracy. So the idea of "randomizing" a deck of cards is to re-order them without having any bias in the new order that we choose.
The way to minimize the bias is to select a permutation of 52 cards, with each permutation equally likely to be chosen. So each permutation has a probability of 1/52! chance of being picked (that's 1 / (52*51*50*49*...*1) ). This "uniform distribution" is the best way to keep someone from being able to predict what card is next, even if they've already seen the previous cards. That's because we don't have any bias in how we are ordering, so there's no extra information for them to take advantage of.
When we do a riffle shuffle we are choosing a new ordering of the cards. Obviously we are choosing our re-ordering in a biased way: we're more likely to have cards from the top and bottom interleaved than we are to reverse the order of the deck for instance. So we have a certain distribution of probabilities on the possible permutations, and this distribution is not uniform.
But what if we riffle shuffle again? Given our original deck order, we now have certain probabilities of choosing the various permutations as our new order. And as it turns out, we're a little less likely to be biased in favor of certain permutations. If we keep riffle shuffling over and over again we're smoothing out our bias and heading towards a uniform distribution.
The question of "how many times do we need to shuffle?" is really "how many times do we need to shuffle to be pretty close to the uniform distribution?" There are technical definitions for what it means to be "close to the uniform distribution", but that's the idea.
So a deck of cards has been "randomized" if I tell you the order it started in, I tell how what procedure I'm going to use to pick a new re-ordering, and you still can't tell what order the deck is likely to be in because my procedure is going to choose any of the possible re-orderings with equal probability. Note that you don't get to peak at the deck after each shuffle, you only get to see it at the start.
As for the imperfection in the shuffling, TFA tells you the model they use: The c
Without Rosa Parks, our next president might have spent his childhood sitting at the back of the bus.
I just want to point out that Barrack grew up in Indonesia and Hawaii. In both places white people are a minority. He was never at risk of sitting in the back of the bus as a child.
It's somewhat irritating to hear people constantly compare the life of a black child in, say, Mississippi to Obama's childhood. They are two completely different experiences and it demonstrates an (somewhat frightening) ignorance of racial issues to treat them as the same.
In fact, it is rather racist to lump them together. African-Americans are not all inter-changable placeholders. There is more to someone than the color of their skin.
The fact that people look no further than Obama's ethnicity when making these statements shows that this country still has a long way to go in racial equality.
You mean the Quicktime Vorbis plug-in that is roughly beta level quality and was last updated a year ago? Before last year's update it was last updated a year before that. I used to use it, but their release cycle just doesn't keep up with Quicktime's updates. It's constantly breaking/broken.
Let me add my voice to this as well. Blizzard has an excellent history of updating old titles, but some old titles have fallen behind. Old classics like Lost Vikings, or "new" classics like Diablo and the first two Warcrafts in particular. They haven't been kept up to date as much (for instance Diablo doesn't run in OS X), and they aren't sold anywhere. Open sourcing would lose little to nothing in terms of income, and would gain a lot in good will and publicity.
Given Blizzard's history of producing extremely portable titles, as well as being able to maintain them for a long period of time, I'm sure there would be a lot to learn for aspiring developers on "how to do it right".
Starcraft does run on modern operating systems, and it has run continuously through all the upgrades of windows as well as Mac OS classic to OS X (aside from a few hitches).
I play it roughly every week on my MacBook Pro, 10.5.5. It works great as well on my G4 iBook running 10.4. It should be noted that 10.5.3 and 10.5.4 had some graphics trouble that prevented it from running on certain MacBook and MacBook Pros, but that was patched by Blizzard and Apple.
You can get the OS X installer from Blizzard's site, but another option is to look into a Blizzard account. They're free to sign up for, and after they've verified your CD keys you can download full versions of the games you own which ought to be patched up. I've heard there was a little trouble with the most recent Starcraft patch on the downloaded version though. Check the battle.net support forums if you have trouble.
There's at least one other updated bnetd solution out there. You probably want to google around for it before you work too hard on the bnetd code.
My worry is that they're going to embed some of the game logic on the B.net side making it harder to emulate since you have to reverse engineer a protocol as well as the game.
There are currently tools out there for emulating a B.net server over a LAN. They are the tragic offspring of bnetd. I sincerely hope that they don't end up sharing the same fate as their progenitor, because D3 just isn't very exciting to me without LAN play.
I still play Starcraft and Warcraft3 on a LAN just about every weekend, and at a location without decent internet access mind you. If D3 doesn't have that option, it's likely my friends and I will just skip over it.
Without the ability to play with friends in a reasonable manner (and having to get business class internet access to support us all simultaneously doesn't count), I don't think D3 will have quite the same staying power as SC1, D2 or War3.
it seems like 10 years ago they only had enough people (or chose to have enough) to work on one big game at a time.
Since the original Diablo, they've always had at least two teams: one at Blizzard North (these were people that made Diablo - they were folded into Blizzard) and Blizzard "south", which was the main team that did things like War2.
At least since the pre-Brood War days they've actually had three teams: one at Blizzard North, two at the main Blizzard site. They may only announce a couple of games, but it's reasonably well-known in the Blizz community that there are "secret" projects being worked on that haven't made it to the "big game" announcement stage. Starcraft:Ghost was one such, as was Warcraft Adventures.
I don't know how many teams they have going now, but it's fair to say that since the Starcraft days they've been working on more than one game at a time - and many times producing two blockbuster games simultaneously.
I too was sorely disappointed by the lack of LAN play. I basically exclusively play off-line with friends. Rest assured, if there isn't a LAN option we'll be making use of bnetd's successor. And if that's blocked by Blizzard, well, I guess D3 doesn't hold quite as much interest for me.
I feel this way as well. I've always thought that Diablo2 had a different atmospheric feel to it - much brighter than the original Diablo. My friends and I have fired up Diablo 1 on several occasions to relive the dark and brooding atmosphere that D2 lacks.
I suspect a lot of people that are complaining about the brightness never played Diablo. Compared to the original these D3 screenshots look about on par with D2 as far as light is concerned.
Interesting that you should mention that. In Hawaii, where almost everything is "off-shore", a gallon of milk costs about $10.
Off-shoring only works as long as you have goods to trade back. If a cargo ship can't haul goods both ways on the route, then the route isn't worth as much of their time, and shipping costs go up. WAY up.
The EFF is trying to get some measure of what level of encryption is required to be secure, i.e. how long of a key do we need? Most people won't go around trying to factor large numbers or test for large primes out of the goodness of their heart. Hence the EFF pays. Assessing the difficulty of finding large primes gives some real-world indication of how hard it is to break encrypted messages of various sizes.
This is false, and demonstrably so. As locofungus points out Liouville's constant is irrational, but only has the number 0 and 1 in its decimal expansion.
Irrational numbers may not have repeating decimals, but that's no guarantee that you can find any combination of numbers. In fact quite the opposite. The examples you list, pi and e, are famously unknown to have the property that any sequence of numbers appears in their expansion. It's actually quite a hard problem.
This is all well and good for secret agents that are transporting information worth far more than their life. If it comes down to a torture situation deniability of this sort is definitely an "un-feature" for Average Joe. I don't know about you, but I'd rather give up my meager data and have my interrogators feel certain that they've got it all than to have "turtles all the way down". If there could always be another turtle, that just means they torture me until I'm completely broken and unable to provide *any* coherent information.
I've run into many similar troubles myself, but a little search usually finds a resolution. I can definitely empathize with your Finder woes. It seems like Finder is universally disliked, but Apple just doesn't have a good enough replacement yet.
As for copying from an old computer, the Migration Assistant can transfer files using a network. I don't know if this is enabled when the Mac first boots, but I've just checked on my MacBook Pro running 10.5. When it asks you to hook up the firewire cable, there's a "network" button that can let you transfer over ethernet or wireless.
I too went through transition pains a few years ago. It can be hard to figure out how to do even basic tasks when you're used to a Windows/Linux way.
The Apple GUI is a piece of shit. They have gone to weird symbols in their GUI instead of nice buttons with labels.
Honestly? Weird symbols? Plus and minus, along with a question mark for help, are all completely standard symbols that anyone with an elementary education should recognize (elementary as in elementary school).
Actually, the more I think about your post the more I think this is too ludicrous to be true. I guess I've been trolled. Hats off to you sir.
Yeah, but Blizzard has been owned by Vivendi for a long long time now without being messed with. I remember when Blizzard was acquired by Vivendi; people had the same worries. Just like Blizzard is famous for only releasing "when it's done", I trust they're willing to tell their higher-ups, "Trust us, we know what we're doing."
Activision would have to be insane to fiddle with Blizzard, given that Blizzard rakes in millions a year, and could probably have a best selling game based on their name alone.
They had physical blood evidence that Nina bled in his car. Doesn't mean she died there, nor that Hans killed her. Seems like that last fact is pretty settled now though.
As a member-in-training of the scientific community, I think you'll find that most scientists agree with you. Unfortunately the system right now is hard to break out of. You need to publish in a reputable journal for job evaluation and tenure purposes, but many reputable journals are under the thumb of the publishers.
In mathematics there have been several mass resignations of journal editorial boards in protest over the price. These editors usually then go on to form a brand new, cheaper journal in the same area. So some progress is being made. I can't say what has been happening in the other sciences though.
Indeed. Among some mathematicians it is a pleasant diversion to take bets on which of the major unsolved (or unprovable) problems has the most solutions appear on the arXiv this week.
There's a lot of misinformation floating around here (RTFA please). Here's what happens: you want to upload a file. The program makes up a bunch of random numbers - really random numbers that have nothing to do with the original file. The original file is not consulted to make the random blocks - they could be pre-generated even.
Also generated is a URL that has the instructions on how to get the original file back from the random blocks. Anyone that shares this part is going to be guilty of copyright infringement (assuming the work in question is copyrighted).
It's basically a substitution cipher - with a unique way of substituting real data for the random blocks, as determined by the URL. So really, it's a one-time pad of sorts.
I've been on more than a couple roofs as a kid (legally even). IMHO it's less dangerous than walking on the sidewalk in the winter. All the roofs around where I live have shingles that are extremely rough - think sandpaper. Unless the roof has water pouring off of it, I'd find it very hard to slip.
Slashdot Mirror
I have to strongly disagree. MTW's Gravitation is not too hard for a mathematician to start with; if anything it is too simplistic. Mathematicians are already well familiar with analysis on manifolds and the explanations of mathematical topics found in Gravitation are not really rigorous enough to be helpful. They tend to confuse more than help.
Remember that these are supposed to be recommendations for a PhD student in math. Books that are too hard for those with an engineering/physics background to start with might very well be phrased in rigorous language that a mathematician would find most helpful.
Since I've RTFA a little (I know, I know, this is slashdot), and IAAM (mathematician) allow me to try to answer.
Whether a deck of cards is "random" or not is a subtle (and somewhat meaningless question). Afterall, the deck might follow a pattern but if I don't know the pattern then it appears random to me. In fact, this is exactly how decks of cards work: you've assigned each card with a number from 1 to 52, and you deal the cards by picking the card that's assigned number 1 first, number 2 second, etc. If I don't know how the numbers are assigned, then I can't tell what's coming next so it looks random. On the other hand, if I know what order you've put the cards in, then nothing is a surprise.
Instead of considering whether a deck is "random" or not, we're more interested in how well one can predict what the order of the cards are: either without seeing any of the cards, or after seeing the first few deals. For instance, if I know that you only order your decks in increasing order of rank with the suits randomly ordered, then seeing that the first deal is an Ace of Hearts tells me what the next 12 cards must be. All because I know how you like to order your cards.
This example, of course, never happens. But if instead of being certain about how you order things, what if I knew that you were more likely to order in a certain way? What if you ordered them as above 50% of the time, and the other 50% you riffle shuffled them? Then seeing an Ace of Hearts on the first deal doesn't make me certain about what's coming next, but I have a pretty good idea. Seeing a Two of Hearts re-affirms my hunch, but I still can't be completely certain.
This still isn't quite a real-life example, but it's getting close. If we know that the person shuffling favors certain orders over other, then we can predict what's coming next with better than chance accuracy. So the idea of "randomizing" a deck of cards is to re-order them without having any bias in the new order that we choose.
The way to minimize the bias is to select a permutation of 52 cards, with each permutation equally likely to be chosen. So each permutation has a probability of 1/52! chance of being picked (that's 1 / (52*51*50*49*...*1) ). This "uniform distribution" is the best way to keep someone from being able to predict what card is next, even if they've already seen the previous cards. That's because we don't have any bias in how we are ordering, so there's no extra information for them to take advantage of.
When we do a riffle shuffle we are choosing a new ordering of the cards. Obviously we are choosing our re-ordering in a biased way: we're more likely to have cards from the top and bottom interleaved than we are to reverse the order of the deck for instance. So we have a certain distribution of probabilities on the possible permutations, and this distribution is not uniform.
But what if we riffle shuffle again? Given our original deck order, we now have certain probabilities of choosing the various permutations as our new order. And as it turns out, we're a little less likely to be biased in favor of certain permutations. If we keep riffle shuffling over and over again we're smoothing out our bias and heading towards a uniform distribution.
The question of "how many times do we need to shuffle?" is really "how many times do we need to shuffle to be pretty close to the uniform distribution?" There are technical definitions for what it means to be "close to the uniform distribution", but that's the idea.
So a deck of cards has been "randomized" if I tell you the order it started in, I tell how what procedure I'm going to use to pick a new re-ordering, and you still can't tell what order the deck is likely to be in because my procedure is going to choose any of the possible re-orderings with equal probability. Note that you don't get to peak at the deck after each shuffle, you only get to see it at the start.
As for the imperfection in the shuffling, TFA tells you the model they use: The c
Without Rosa Parks, our next president might have spent his childhood sitting at the back of the bus.
I just want to point out that Barrack grew up in Indonesia and Hawaii. In both places white people are a minority. He was never at risk of sitting in the back of the bus as a child.
It's somewhat irritating to hear people constantly compare the life of a black child in, say, Mississippi to Obama's childhood. They are two completely different experiences and it demonstrates an (somewhat frightening) ignorance of racial issues to treat them as the same.
In fact, it is rather racist to lump them together. African-Americans are not all inter-changable placeholders. There is more to someone than the color of their skin.
The fact that people look no further than Obama's ethnicity when making these statements shows that this country still has a long way to go in racial equality.
You mean the Quicktime Vorbis plug-in that is roughly beta level quality and was last updated a year ago? Before last year's update it was last updated a year before that. I used to use it, but their release cycle just doesn't keep up with Quicktime's updates. It's constantly breaking/broken.
Let me add my voice to this as well. Blizzard has an excellent history of updating old titles, but some old titles have fallen behind. Old classics like Lost Vikings, or "new" classics like Diablo and the first two Warcrafts in particular. They haven't been kept up to date as much (for instance Diablo doesn't run in OS X), and they aren't sold anywhere. Open sourcing would lose little to nothing in terms of income, and would gain a lot in good will and publicity.
Given Blizzard's history of producing extremely portable titles, as well as being able to maintain them for a long period of time, I'm sure there would be a lot to learn for aspiring developers on "how to do it right".
Starcraft does run on modern operating systems, and it has run continuously through all the upgrades of windows as well as Mac OS classic to OS X (aside from a few hitches).
I play it roughly every week on my MacBook Pro, 10.5.5. It works great as well on my G4 iBook running 10.4. It should be noted that 10.5.3 and 10.5.4 had some graphics trouble that prevented it from running on certain MacBook and MacBook Pros, but that was patched by Blizzard and Apple.
You can get the OS X installer from Blizzard's site, but another option is to look into a Blizzard account. They're free to sign up for, and after they've verified your CD keys you can download full versions of the games you own which ought to be patched up. I've heard there was a little trouble with the most recent Starcraft patch on the downloaded version though. Check the battle.net support forums if you have trouble.
There's at least one other updated bnetd solution out there. You probably want to google around for it before you work too hard on the bnetd code.
My worry is that they're going to embed some of the game logic on the B.net side making it harder to emulate since you have to reverse engineer a protocol as well as the game.
Hear hear!
There are currently tools out there for emulating a B.net server over a LAN. They are the tragic offspring of bnetd. I sincerely hope that they don't end up sharing the same fate as their progenitor, because D3 just isn't very exciting to me without LAN play.
I still play Starcraft and Warcraft3 on a LAN just about every weekend, and at a location without decent internet access mind you. If D3 doesn't have that option, it's likely my friends and I will just skip over it.
Without the ability to play with friends in a reasonable manner (and having to get business class internet access to support us all simultaneously doesn't count), I don't think D3 will have quite the same staying power as SC1, D2 or War3.
it seems like 10 years ago they only had enough people (or chose to have enough) to work on one big game at a time.
Since the original Diablo, they've always had at least two teams: one at Blizzard North (these were people that made Diablo - they were folded into Blizzard) and Blizzard "south", which was the main team that did things like War2.
At least since the pre-Brood War days they've actually had three teams: one at Blizzard North, two at the main Blizzard site. They may only announce a couple of games, but it's reasonably well-known in the Blizz community that there are "secret" projects being worked on that haven't made it to the "big game" announcement stage. Starcraft:Ghost was one such, as was Warcraft Adventures.
I don't know how many teams they have going now, but it's fair to say that since the Starcraft days they've been working on more than one game at a time - and many times producing two blockbuster games simultaneously.
I too was sorely disappointed by the lack of LAN play. I basically exclusively play off-line with friends. Rest assured, if there isn't a LAN option we'll be making use of bnetd's successor. And if that's blocked by Blizzard, well, I guess D3 doesn't hold quite as much interest for me.
That sucks.
bnetd where are you?!?
I feel this way as well. I've always thought that Diablo2 had a different atmospheric feel to it - much brighter than the original Diablo. My friends and I have fired up Diablo 1 on several occasions to relive the dark and brooding atmosphere that D2 lacks.
I suspect a lot of people that are complaining about the brightness never played Diablo. Compared to the original these D3 screenshots look about on par with D2 as far as light is concerned.
Isn't this even more pertinent to the concept of anthropogenic warming than the absolute dating article Slashdot went with???
Maybe it is. After all, it was posted on Slashdot a few weeks before this article.
Would you want to pay $10 for a gallon of milk?
Interesting that you should mention that. In Hawaii, where almost everything is "off-shore", a gallon of milk costs about $10.
Off-shoring only works as long as you have goods to trade back. If a cargo ship can't haul goods both ways on the route, then the route isn't worth as much of their time, and shipping costs go up. WAY up.
The EFF is trying to get some measure of what level of encryption is required to be secure, i.e. how long of a key do we need? Most people won't go around trying to factor large numbers or test for large primes out of the goodness of their heart. Hence the EFF pays. Assessing the difficulty of finding large primes gives some real-world indication of how hard it is to break encrypted messages of various sizes.
This is false, and demonstrably so. As locofungus points out Liouville's constant is irrational, but only has the number 0 and 1 in its decimal expansion.
Irrational numbers may not have repeating decimals, but that's no guarantee that you can find any combination of numbers. In fact quite the opposite. The examples you list, pi and e, are famously unknown to have the property that any sequence of numbers appears in their expansion. It's actually quite a hard problem.
This is all well and good for secret agents that are transporting information worth far more than their life. If it comes down to a torture situation deniability of this sort is definitely an "un-feature" for Average Joe. I don't know about you, but I'd rather give up my meager data and have my interrogators feel certain that they've got it all than to have "turtles all the way down". If there could always be another turtle, that just means they torture me until I'm completely broken and unable to provide *any* coherent information.
I've run into many similar troubles myself, but a little search usually finds a resolution. I can definitely empathize with your Finder woes. It seems like Finder is universally disliked, but Apple just doesn't have a good enough replacement yet.
As for copying from an old computer, the Migration Assistant can transfer files using a network. I don't know if this is enabled when the Mac first boots, but I've just checked on my MacBook Pro running 10.5. When it asks you to hook up the firewire cable, there's a "network" button that can let you transfer over ethernet or wireless.
Hope that helps
The Apple GUI is a piece of shit. They have gone to weird symbols in their GUI instead of nice buttons with labels.
Honestly? Weird symbols? Plus and minus, along with a question mark for help, are all completely standard symbols that anyone with an elementary education should recognize (elementary as in elementary school). Actually, the more I think about your post the more I think this is too ludicrous to be true. I guess I've been trolled. Hats off to you sir.
Yeah, but Blizzard has been owned by Vivendi for a long long time now without being messed with. I remember when Blizzard was acquired by Vivendi; people had the same worries. Just like Blizzard is famous for only releasing "when it's done", I trust they're willing to tell their higher-ups, "Trust us, we know what we're doing."
Activision would have to be insane to fiddle with Blizzard, given that Blizzard rakes in millions a year, and could probably have a best selling game based on their name alone.
They had physical blood evidence that Nina bled in his car. Doesn't mean she died there, nor that Hans killed her. Seems like that last fact is pretty settled now though.
As a member-in-training of the scientific community, I think you'll find that most scientists agree with you. Unfortunately the system right now is hard to break out of. You need to publish in a reputable journal for job evaluation and tenure purposes, but many reputable journals are under the thumb of the publishers.
In mathematics there have been several mass resignations of journal editorial boards in protest over the price. These editors usually then go on to form a brand new, cheaper journal in the same area. So some progress is being made. I can't say what has been happening in the other sciences though.
Indeed. Among some mathematicians it is a pleasant diversion to take bets on which of the major unsolved (or unprovable) problems has the most solutions appear on the arXiv this week.
There's a lot of misinformation floating around here (RTFA please). Here's what happens: you want to upload a file. The program makes up a bunch of random numbers - really random numbers that have nothing to do with the original file. The original file is not consulted to make the random blocks - they could be pre-generated even.
Also generated is a URL that has the instructions on how to get the original file back from the random blocks. Anyone that shares this part is going to be guilty of copyright infringement (assuming the work in question is copyrighted).
It's basically a substitution cipher - with a unique way of substituting real data for the random blocks, as determined by the URL. So really, it's a one-time pad of sorts.
I've been on more than a couple roofs as a kid (legally even). IMHO it's less dangerous than walking on the sidewalk in the winter. All the roofs around where I live have shingles that are extremely rough - think sandpaper. Unless the roof has water pouring off of it, I'd find it very hard to slip.