Ah... Your hint was very helpful. I think I know where the dog is buried. You gave an example where knowing that Phy was different from knowing that Alice knows that Phy. The situation on the island is a tad bit more complicated. Like I said before, it is fair to suppose that they all know that guru knows that someone has blue eyes. The problem is, they know it through a derivation. Alice has to establish that there is a person on the island (Bob) who has blue eyes and is not Alice. Only then she would be able to conclude that guru must know someone with blue eyes. In order for Alice to assert that Bob knows that guru knows that someone has blue eyes, Alice must find yet another blue-eyed person (Charley), so that she can be certain that Bob can derive this fact on his own. And so it goes. In the end, given all blue-eyed people x1, x2, x3,... , xn, it is impossible for x1 to derive that x2 knows that x3 knows that... that xn knows that guru knows that someone has blue eyes. Impossible, because x1 must start by asserting that there is a distinct y != xi with blue eyes. And that is too bad, because the solution to the problem is hidden in the bottom of this chain of knowledge operators.
When guru speaks, the statement "guru knows that there exists a person with blue eyes" becomes a thesis (in other contexts: a logical axiom), i.e. it no longer requires any derivation. Those dirty tricks they use in modal logic... Now, the statements like above (including the last one -- the one that matters) have trivial derivations, because islanders can always assume that others know axioms. So, as I suspected, no new information is conferred, but rather the logical system is changed.
Beautiful problem, I'll be sure to mention you at school:)
You've made my day. I have some background in mathematical logic, and the first reaction was: IMPOSSIBLE! She only tells them what they already know! After I got over the initial shock, I considered cases with 1, 2, 3 blue-eyed people, and got the answer easily.
But, as one of my (logic) professors used to say, sometimes we can derive it, but we cannot understand it. I am still in the dark about this question: what exactly is the vital piece of knowledge that is acquired after the guru speaks? I figured that I have to get involved with the modal logic, so I am plugging in a knowledge operator, Kx(phi), and quantification over formulas.
E: Exists
A: For all
x, y, g: people vars
i: self var
Kx(phy): x knows that phi
Bx: x has blue eyes
It is fair to suppose that with at least 3 blue-eyed people on the island, everyone knows simple things like
Ex(Bx)
Ex(x != i ^ Bx)
Ax(Kx(Ey(y != i ^ By)))
And the guru seems to be saying that Ex(x != i ^ Bx), so it is fair to suppose that after the fact everyone perceives that Eg(g != i ^ ~Bg ^ Kg(Ex(x != i ^ Bx))). The problem is, it feels like they should have known that anyway, from the beginning.
At this point, I tip my hat to you. It really boggles my mind that I have found a solution, but have no idea how to formalize it. I don't suppose I'll be able to go to sleep before I crack this one...
Emacs is one of the worst examples of code bloat I've ever
seen.
That is precisely my point. No one in his right mind thinks that Emacs is bug-free. But even if you are taking a side in the editor war, you know (you don't have to admit it), you know deep inside of you that Emacs is an amazing piece of software, the kind that takes a very special person to write.
You are missing the point, though not as badly as the grandparent.
It takes a genius to write an amazing program like TeX or Emacs, but no genius is required to write a program that is free of bugs.
To compare with something I understand, it takes a person like Gauss to prove the law of quadratic reciprocity, but even a very average graduate student can understand it and to check that the proof is correct.
As a working mathematician with some background in computer science, I am willing to attest that writing low-level software is wrought with many perils which mathematicians never encounter. Closed source, incompatible devices, hardware failures -- factors like these make programming a device driver very different from proving a theorem. But, in my humble opinion, there is absolutely no excuse for writing a buggy word processor over a well-documented API. In a high-level environment like this a program can and should be designed in a way that allows provability of correctness. Throw in practices like peer review and modular design and you will have college kids writing bug-free software in no time.
Oh hehe, I understood that. My post was just an asshole's way of pointing out that RIAA is in fact the very entity that is TAKING hits away from artists, in terms of both copyrights and profits.
Unhappy Birthday is a grassroots project run by citizens who are outraged by rampant copyright infringement in today's society -- particularly in relation to the song Happy Birthday.
Nice link. I cannot figure out if these guys are serious.
Just a few days ago I was making a presentation in GIMP 2.2 for one of my friends, and we wanted to put some text along a circle arc. No luck. I tried to use Text Circle thing, but it wouldn't work because I had accented (Spanish) characters in the text string. Finally, we just went with an ugly curve bend.
I wonder if that feature will be implemented in 2.4...
I like to distinguish between OSX and Aqua. OSX itself is a breeze to use on a laptop, if any GNU or BSD flavour is. Aqua, on the other hand, is a mixed bag. It is slick and streamlined (compared to Windows) and has a few nice features (expose comes to mind), but I would give anything to be able to run a good WM, like WindowMaker or XFCE, without sacrificing Quartz. IMO, it all comes down to the fact that proprietary components of OSX will always suck, if only because we have absolutely no control over them.
Just an example: there is no way, bar writing a
script which will traverse the filesystem tree, to change view options in all folders. This is not OS/9, I am talking Tiger. Sounds stupid? It does to me, and so my non-techie friends never fail to be entertained when they see me opening the command line to "drag and drop" a few files.
Another great example is the printer setup. It is abominable, I cannot do anything there. After a while I just gave up and started using CUPS' web interface, which is enabled by default. This again shows how sane the underlying OS is.
Seriously, of course it does not make any sense for the retailer. It is the gamers' right! You know, just like retailers have a right to refuse service to people not wearing shoes. I like going barefoot but I won't cry about getting kicked out of Best Buy for that because I respect their right to be selective.
And also, retailers do not have to eat the returns. They can simply pass them over to designers. I completely agree that it is in the designers' best interest to make cheap knock-offs that sell in virtue of the brand recognition. This is precisely my point. As a gamer, I need to have a right to return this crap, whether they like it or not.
On a personal note: I haven't bought a single game since WoW came out, but I played many warez versions. Still, I guarantee you, if I had the above right, I would actually buy games and keep some of them, dirty criminal that I am...
Chat windows are already there. I just thought of voice- or may be video-conferencing. That would be next to impossible to defeat. Sure, it will not stop bot-assisted play, but bots are simply not good enough to "assist" against even average players. And at the low stakes against terrible players bot-assisted play would be very boring and barely profitable.
They work really badly anywhere except at (1) long-hand (2) fixed limit (3) low stakes (4) loose (5) passive tables where the winning strategy is clear and mostly consists of waiting for a good hand and then playing pot odds correctly. If anyone is so bored that they are willing to babysit a bot which makes less than $1 per hour, more power to them.
It is all about complete automation. Without it these bots are useless because it is simply not fun to play the long-hand fixed limit poker correctly. Take it from an avid hold'em player.
Here's a thought: TFA says that the online poker biz already makes $1.4 billion annualy. Now this cash will pay for R&D of The Perfect CAPTCHA. This will be interesting to watch.
We knew it would happen sooner or later. I do not see it as a big deal though. I find the live play with my friends or in a local poker room much more satysfying anyway.
A hot button for me. Since I just got slapped on the wrist by ESA for selling my WoW account on eBay, the one feature that I really want is being able to sell my account and its contents. I used to think that SOE is gay, but once I realized that I can retire for $400 I, like, totally re-evaluated my entire life.
Slashdot Mirror
Ah... Your hint was very helpful. I think I know where the dog is buried. You gave an example where knowing that Phy was different from knowing that Alice knows that Phy. The situation on the island is a tad bit more complicated. Like I said before, it is fair to suppose that they all know that guru knows that someone has blue eyes. The problem is, they know it through a derivation. Alice has to establish that there is a person on the island (Bob) who has blue eyes and is not Alice. Only then she would be able to conclude that guru must know someone with blue eyes. In order for Alice to assert that Bob knows that guru knows that someone has blue eyes, Alice must find yet another blue-eyed person (Charley), so that she can be certain that Bob can derive this fact on his own. And so it goes. In the end, given all blue-eyed people x1, x2, x3, ... , xn, it is impossible for x1 to derive that x2 knows that x3 knows that ... that xn knows that guru knows that someone has blue eyes. Impossible, because x1 must start by asserting that there is a distinct y != xi with blue eyes. And that is too bad, because the solution to the problem is hidden in the bottom of this chain of knowledge operators.
When guru speaks, the statement "guru knows that there exists a person with blue eyes" becomes a thesis (in other contexts: a logical axiom), i.e. it no longer requires any derivation. Those dirty tricks they use in modal logic... Now, the statements like above (including the last one -- the one that matters) have trivial derivations, because islanders can always assume that others know axioms. So, as I suspected, no new information is conferred, but rather the logical system is changed.
Beautiful problem, I'll be sure to mention you at school :)
You've made my day. I have some background in mathematical logic, and the first reaction was: IMPOSSIBLE! She only tells them what they already know! After I got over the initial shock, I considered cases with 1, 2, 3 blue-eyed people, and got the answer easily.
But, as one of my (logic) professors used to say, sometimes we can derive it, but we cannot understand it. I am still in the dark about this question: what exactly is the vital piece of knowledge that is acquired after the guru speaks? I figured that I have to get involved with the modal logic, so I am plugging in a knowledge operator, Kx(phi), and quantification over formulas.
It is fair to suppose that with at least 3 blue-eyed people on the island, everyone knows simple things like
And the guru seems to be saying that Ex(x != i ^ Bx), so it is fair to suppose that after the fact everyone perceives that Eg(g != i ^ ~Bg ^ Kg(Ex(x != i ^ Bx))). The problem is, it feels like they should have known that anyway, from the beginning.
At this point, I tip my hat to you. It really boggles my mind that I have found a solution, but have no idea how to formalize it. I don't suppose I'll be able to go to sleep before I crack this one...
Emacs is one of the worst examples of code bloat I've ever seen.
That is precisely my point. No one in his right mind thinks that Emacs is bug-free. But even if you are taking a side in the editor war, you know (you don't have to admit it), you know deep inside of you that Emacs is an amazing piece of software, the kind that takes a very special person to write.
You are missing the point, though not as badly as the grandparent.
It takes a genius to write an amazing program like TeX or Emacs, but no genius is required to write a program that is free of bugs.
To compare with something I understand, it takes a person like Gauss to prove the law of quadratic reciprocity, but even a very average graduate student can understand it and to check that the proof is correct.
As a working mathematician with some background in computer science, I am willing to attest that writing low-level software is wrought with many perils which mathematicians never encounter. Closed source, incompatible devices, hardware failures -- factors like these make programming a device driver very different from proving a theorem. But, in my humble opinion, there is absolutely no excuse for writing a buggy word processor over a well-documented API. In a high-level environment like this a program can and should be designed in a way that allows provability of correctness. Throw in practices like peer review and modular design and you will have college kids writing bug-free software in no time.
Oh hehe, I understood that. My post was just an asshole's way of pointing out that RIAA is in fact the very entity that is TAKING hits away from artists, in terms of both copyrights and profits.
Unhappy Birthday is a grassroots project run by citizens who are outraged by rampant copyright infringement in today's society -- particularly in relation to the song Happy Birthday.
Nice link. I cannot figure out if these guys are serious.
Well, I think we DO need the RIAA. For example, if you write a hit song, and someone else TAKES it...
Am I missing something here? By "someone", you must mean RIAA, right?
Just a few days ago I was making a presentation in GIMP 2.2 for one of my friends, and we wanted to put some text along a circle arc. No luck. I tried to use Text Circle thing, but it wouldn't work because I had accented (Spanish) characters in the text string. Finally, we just went with an ugly curve bend.
I wonder if that feature will be implemented in 2.4...
Mod parent up please, the smartest thing I read today.
Except... You have ubergeek distros like gentoo
You misspelled Slackware
I agree. Yet another reason to run WindowMaker :P
In other news: Slashdot has an article covering a gaming site's editorial covering the game coverage in press.
I like to distinguish between OSX and Aqua. OSX itself is a breeze to use on a laptop, if any GNU or BSD flavour is. Aqua, on the other hand, is a mixed bag. It is slick and streamlined (compared to Windows) and has a few nice features (expose comes to mind), but I would give anything to be able to run a good WM, like WindowMaker or XFCE, without sacrificing Quartz. IMO, it all comes down to the fact that proprietary components of OSX will always suck, if only because we have absolutely no control over them.
Just an example: there is no way, bar writing a script which will traverse the filesystem tree, to change view options in all folders. This is not OS/9, I am talking Tiger. Sounds stupid? It does to me, and so my non-techie friends never fail to be entertained when they see me opening the command line to "drag and drop" a few files.
Another great example is the printer setup. It is abominable, I cannot do anything there. After a while I just gave up and started using CUPS' web interface, which is enabled by default. This again shows how sane the underlying OS is.
Heresy! Emacs reads all!
LOL that's funny as hell.
Seriously, of course it does not make any sense for the retailer. It is the gamers' right! You know, just like retailers have a right to refuse service to people not wearing shoes. I like going barefoot but I won't cry about getting kicked out of Best Buy for that because I respect their right to be selective.
And also, retailers do not have to eat the returns. They can simply pass them over to designers. I completely agree that it is in the designers' best interest to make cheap knock-offs that sell in virtue of the brand recognition. This is precisely my point. As a gamer, I need to have a right to return this crap, whether they like it or not.
On a personal note: I haven't bought a single game since WoW came out, but I played many warez versions. Still, I guarantee you, if I had the above right, I would actually buy games and keep some of them, dirty criminal that I am...
This and other bills are too long. I think that all of the points in all of these bills will be addressed if we only get the right to
(0) Return a game for a full refund if we do not like it.
Chat windows are already there. I just thought of voice- or may be video-conferencing. That would be next to impossible to defeat. Sure, it will not stop bot-assisted play, but bots are simply not good enough to "assist" against even average players. And at the low stakes against terrible players bot-assisted play would be very boring and barely profitable.
They work really badly anywhere except at (1) long-hand (2) fixed limit (3) low stakes (4) loose (5) passive tables where the winning strategy is clear and mostly consists of waiting for a good hand and then playing pot odds correctly. If anyone is so bored that they are willing to babysit a bot which makes less than $1 per hour, more power to them.
It is all about complete automation. Without it these bots are useless because it is simply not fun to play the long-hand fixed limit poker correctly. Take it from an avid hold'em player.
Care to provide a link to the algorithm description? I cannot find one.
Here's a thought: TFA says that the online poker biz already makes $1.4 billion annualy. Now this cash will pay for R&D of The Perfect CAPTCHA. This will be interesting to watch.
We knew it would happen sooner or later. I do not see it as a big deal though. I find the live play with my friends or in a local poker room much more satysfying anyway.
Dupe
I can't seem to play this movie using mplayer. Does it mean I would have to install MSMP for OSX? Sorry, project something, you lost me at "hello"...
A hot button for me. Since I just got slapped on the wrist by ESA for selling my WoW account on eBay, the one feature that I really want is being able to sell my account and its contents. I used to think that SOE is gay, but once I realized that I can retire for $400 I, like, totally re-evaluated my entire life.
Missing option:
The Ugly!