skysight-inc/HackerNews huggingface dataset:
Nope. Announcing the gender of one child does not magically alter the gender of the other child. It's like a print statement in code. If you don't believe me, try writing some code to simulate this. I will bet you an arbitrary amount of money that I'm right :)

Here's another way of looking at it: By your logic, if I announce that one of the children is a girl, then the other child only has a 1/3 chance of also being a girl. Likewise, if I announce that one of the children is a boy, then the other child only has a 1/3 chance of being a boy. Therefore, by your logic, the act of my arbitrarily announcing the gender of one of the children increases the probability that the other child is of the opposite gender from 1/2 (what it was before I spoke) to 2/3, regardless of whether I said it was a girl or boy. Hopefully you can see why this is not correct.
Personally I do not care much about profanity, it's the excess of words that annoys me the most - it steals my time. I wish people learned to write succinctly.
Sorry, rereading the comment I see that it could have been clearer.

What I was talking about is what economists call a true public service. This is a service that doesn't diminish in value when you add more users - a light tower is the classic example: The lighttower is as good a service to a ship whether it is the only one using it or there are a thousand others. Webpages are another good example.

Large countries have an advantage here: It costs the same to build a lighttower whether you are the US or Lichtenstein.

The military might have been a bad example though...
> Once you've figured out what it'd cost, then you can start figuring out "is it worth it?"

There's more to it than money. Public school teaching is currently a lousy job for a number of reasons:

* very large amounts of work to take home

* having to deal with complaints from parents and administrators if you raise the rigor of your classes

* if you're male, the possibility of losing your career if a female student decides to lie and say you did something wrong

* the monotony of only a small portion of your work being actually academic-related. Most of the work is babysitting-style work or else administrative work. For people who like to work with their minds, this is a big deal and a reason against going into teaching.

Also, I don't know where you're getting your numbers from. Who (non-teachers) is making these enormous salaries you quote? Those are big numbers.
Ordering is irrelevant here. Options 2 and 3 are identical.
What prevents a cartel of home owners/buyers from taking out mortgages from a single small issuer, stopping payment en-masse, hoping to push the issuer into insolvency and drive down the value of those bonds and buy them on the open market?
Wouldn't the content of the blogs be availabe in the internet archive? Not sure about the url, maybe archive.org?
"Announcing the gender of one child does not magically alter the gender of the other child."

Nor is that what I said. :)

Assuming you meant "chance of being a boy" where you said "chance of being a girl", I agree that announcing the gender of one of the two children increases the probability of the other child being the opposite gender from 1/2 to 2/3.

The reason this is so is that some of the original probability was sunk in a case you've now eliminated: the case where there were two of the gender you didn't announce.

[Edit: Jeff already wrote some code, and while I haven't bothered to review it, I assume the lack of outcry about it indicates its correctness. Care to share where he got that wrong?]
randallsquared is correct. You are misunderstanding sequences of related events.

Running the roulette wheel twice is a sequence of unrelated events. The (ideal) roulette wheel is totally random. The results of run #1 are unrelated to the results of run #2.

However, in this case of the man and woman both having two children, one of which is a boy, but the man having as an oldest child a boy we are talking about two different scenarios. The events are suddenly related. If you want it spelled out, the matrices are,

The childbirth options are this,

BB
BG
GB
GG

However, for the man it's been stated that his oldest child is a boy, so it becomes,

BB
BG
XX
XX

For the woman (who has as a condition 'at least one boy, but not necessarily the eldest') it is,

BB
BG
GB
XX

(Where 'B' is Boy, 'G' is Girl and 'X' is a non-option).
I wrote a blog in Django(not gonna use it, im a happy blogger.com user, just wanted to learn Django). Most of the time i was just reading documentation, because i don't know the API, the actual code is really short, like 2 classes and a handful of functions for the entire site.

Also, today my mouse died(good thing i had a spare), and i used its transparent case, its USB cable and a few LEDs i had laying around and made a desktop lamp to light my keyboard.

Mostly toy projects, to amuse my self, nothing worth showing to people, hope to improve next year :D
> When you have a group of dedicated, wealthy, involved parents, these negative incentives can be overcome.

I'd go further and say you don't even need the wealth -- just dedicated and involved parents. Success will flow from that. Trouble is, it's a vicious cycle: the kids who need the most help often have the least dedicated and involved parents.

People claim that private schools are better than public for all sorts of reasons, but I think the main reason probably is that the parents who care enough to put their kids in private school usually also care enough to be dedicated to and involved in their child's education.
Options 2 and 3 each still have the same probability weight as each of options 1 and 4.
$9.99/mo sub) or comes with ads

Sounds like a concession.
70% off for 2 years of hosting at Dreamhost
This is precisely the first subtility you encounter when you learn probabilities : they are not identical. Paul is right that the formulation of the question doesn't refer to the Monty Hall problem at all, this isn't the same algorithm. But in this case, the probability turns out to be the same. That's the real confusion in Jeff's article.

I mean, it's not even my own deduction, it's what you are taught when you learn probabilities. It's a basic and core paradigm, and I'll digg it up from Wikipedia if somebody still doubts it :)
Warning - expires January 4th.

And it was even better: 95% off: http://www.quickonlinetips.com/archives/2009/01/dreamhost-ne...
Inventors get screwed by corporations and now by universities. The bit about MIT demanding royalties from the inventor was nasty but expected. But when RPI was demanding royalties even though they had zero input in creating the "idea" and supplied nothing towards inventing it, is outrageous to me.
So if I ask all of my friends who have two children to "tell me the gender of one of their children", then you think that after they answer the question, there is a 2/3 chance they have both a boy and a girl? (but before answering the question the probability was 1/2) Doesn't that seem a little absurd to you?

If Jeff wrote code that yielded 2/3, then he was implementing my "algorithm 1" (which has selection), not the second algorithm (which does not do any selection).

I just updated my post with an explanation that may clear things up for you.
In Jeff's post the question was posed to show how bad humans are at probabilities, and it got the point across very well. I know that I fell right into the trap...

This post takes what was meant to be an enlightening and refreshing take on how bad we as humans are at probabilities and turns it into a numbers-duel.

No the original questions doesn't clearly state the definition of who is asked, it doesn't take into account that slightly more girls than boys are born, and it doesn't answer the question about whether this all happened in a cult where all boys are killed at birth. It was a simple metaphor. And it worked...

Here is a TED talk about the subject of how we are fooled by probabilities: http://www.ted.com/index.php/talks/peter_donnelly_shows_how_...
The Facebook vs. Breast Feeders War Continues
I would try just looking at the x86 manual by Intel. Just looking up the different operations might be all you need.
Really, a (not the, but a) problem is that almost everybody is right. We are certainly fooled by probability. But also, if someone volunteers that one out of their two children is a girl, then it's effectively-100% that the other is a boy, in real life.

Slightly amending a quote in a similar context from "Principles of Economics, Explained" (http://www.youtube.com/watch?v=VVp8UGjECt4), nobody says "I have a girl. I have another girl. I have another girl."

One way of interpreting this perennial debate is as proof of how just how fuzzy English can be. People aren't just arguing about the answer, they argue about the question too.
Loose profanity is a direct cause of peoples inability to communicate succinctly. Frequent profanity becomes a verbal crutch people fall on in order to lend force to there words. Instead, they weaken the use of profanity and limit there vocabulary.
damnit, "their". That's the second time today.
Ask HN: New Ubuntu Desktop--what would you install?
I'm shopping for useful linux programs. I've used linux mainly on servers, but now I'm switching so my dev environment matches production more closely,and installing ubuntu desktop. What would you install on a fresh Ubuntu desktop?
2009 May Smile on Disruptive Startups
The question "what is the gender of one of your children" gives you some information about the gender of both of their children. It's enough information to eliminate the case where both children are the gender opposite the one they mentioned.

It can still be the case that the chances of there being a boy and a girl are 1/2, while the chances of there being a boy after you find out about a girl are 1/3, purely because you don't know whether you found out about an older or younger girl. Probability is just a function of our ignorance (at least in this case; I'm not qualified to have an opinion about whether it always is).

[Edit: Hm. Looking again, it seems Jeff Atwood's code is for a different problem he was also discussing, so nevermind. After considering your update, I think you might be right.]

[Further edit follows:]

Here's some python that essentially shows you're correct, unless I flubbed it:

firstpickwasboy = {'boy':0, 'girl':0}
firstpickwasgirl = {'boy':0, 'girl':0}

choices = ['boy', 'girl']

for i in range(100000):
children = [random.choice(choices), random.choice(choices)]
whichchild = random.randint(0, 1)
otherchild = 1
if(whichchild): otherchild = 0
if(children[whichchild]=='boy'):
firstpickwasboy[children[otherchild]] += 1
else:
firstpickwasgirl[children[otherchild]] += 1

>>> firstpickwasboy
{'boy': 25132, 'girl': 25116}
>>> firstpickwasgirl
{'boy': 24679, 'girl': 25073}
Yep, the exact same code, hosted on Google AppEngine.
At a dollar each pair (from the full article), he could sell them in the developed world at a massive profit, then use the money to subsidize spreading them through the developing world. Even if they're not as attractive or usable as glass lens (and the article doesn't suggest that at all) they'd be disposable. $20 for glasses I don't have to worry about losing? I'd buy a pair.
"But also, if someone volunteers that one out of their two children is a girl, then it's effectively-100% that the other is a boy, in real life."

Well, yes, because saying one is implies that the other isn't, in speech. But we could talk about sets of two of anything that has a 50% probability.
Bright New Phone Displays That Don’t Guzzle Power
Innovation Should Mean More Jobs, Not Less
Also, I have not played with compiz, and I'm wondering if people have found it to be straightforward and easy to live with? It looks fun, but if it makes my life harder. Thoughts?
This guy's response is great, see his profile picture: http://profile.ak.facebook.com/v225/1392/39/n1401257834_1127... ...possibly slightly nsfw.

Found here http://www.facebook.com/topic.php?uid=2517126532&topic=7...
Nice application, but to compete with piracy:

( Ads || $9.99_a_month ) > (free && higher quality) = false

Granted their app might be easier to use compared to searching the piratebay, downloading and playing (disclaimer: not that I'm saying I do that.) , but you can't put the music in your ipod, you can't use it if you are offline.
Wikipedia's Jimmy Wales Out of a Job
Enterprise drive makers like Seagate and WD are now claiming to have features which limit the damage caused by cabinet vibrations. I was intrigued to note that these differences are done only with firmware.

Any idea whats happening behind the scenes? I assume Seagate measured the common vibration frequencies and conteract them with head movements?
Amarok--It's a KDE music player, and it's really good. It seems faster than rhythmbox, has good librarying, and even integrates with Last.fm

I like konversation (another KDE program) as my IRC client, but I've only dabbled in the other ones briefly.

(Note: your first few KDE programs take awhile to install because they have to install a lot of kde libraries and the like.)

Opera--It's not in the package manager, but it's an easy install from http://opera.com, and it's faster and in some cases better than FF. For example, Firefox doesn't like being disconnected and won't let you get even to localhost when it's in "offline mode" without some tweaking.

Your favorite editor, obviously (both emacs and vim are in the package manager).

If you have a slower computer, I suggest looking into other windowing systems. Up until a month ago, my main computer was an ancient computer with 384MB of RAM and a 1.6GHz single-core processor. Awhile ago my productivity was being hurt so much that I looked into minimalist window managers. I chose icewm, but there are other good ones. It really did make a big difference.
Its nice that they release the fruit of their labours in OpenSolaris.

I've rolled my own hybrid storage and played with it in ZFS using a RAM disk and flash storage and it really does work - it can make a RAID of slow SATA disks look like a bigger RAID of fast 15krpm disks, provided all your workload fits in the various ramdisk/flash caches.
$20 glasses? What about $8 glasses ordered online and shipped from Hong Kong? A friend of mine got these and they're definitely cheaper-feeling than your typical $130 pair, but at 8 bucks a pop, you can get a whole bunch and you're bound to like one of 'em:

http://zennioptical.com

(I'm not affiliated with them in anyway... just another near-sighted person happy about cheap glasses)
I actually haven't even migrated off the FreeBSD servers yet. I'll go when they tell me to, but I don't need anything more than I've got.

I've had them for 3 years and been very happy with their service. (Though I agree that their long-promised big improvements sure haven't happened since becoming Joyent).
This quote from Richard Moross, CEO of Moo, on how to assess business ideas in 2009 was interesting:

Is this really a business? Is it really different? If the elevator pitch includes the words ‘Twitter’,
‘social network’ or ‘it’s web app X meets geek meme Y’ you probably need to rethink things - those
days are gone. Today your idea needs to be super-relevant: do people actually need this, or are you
just a solution looking for a problem?

Full interview here - http://www.guardian.co.uk/media/pda/2008/dec/25/digitalmedia...
No.

You've gained no useful information. The person who announces the gender of one child can say one of two things: "this child is a girl" or "this child is a boy." However, these two statements are symmetric in their effect on P(one child is a girl and one is a boy).

There's a huge difference between announcing the gender of one child and announcing the gender of both children. If the announcer announces both children's genders, he can say that "both are boys," that "both are girls," or that "one is a boy and one is a girl." But the last statement is not symmetric to the first two in how it affects P(one child is a boy and one is a girl).
Good point. Ok, then $4 a pair. Gonna go look for my prescription so I can buy some $8 glasses now, thanks.
Does anyone know if there was ever a case of a university suing to enforce a patent it holds?
Who The Hell Writes Wikipedia, Anyway?
Twitter Wildfire Spread On The Jannawalitax Scam Like A Pack Of Wolves
Nginx vs Yaws vs MochiWeb : Web Server Performance Deathmatch, Part 2
I'm willing to bet $5 that the probability (according to the current statistical science corpus) is still 2/3 (even if you're right that announcing the child doesn't alter the sex of the other). See my comment in the main thread.
Some of the apps I use frequently

XVidCap - if you want to make screencasts

KdenLive - for video editing

(and unstripped codecs, I re-compiled ffmpeg)

MySQL Administrator and Query Browser - for pokin around MySQL

VirtualBox - for running other OSes
just to be clear, this article is hardly about hunter college high school, and hchs is not a cram school. the subject is a "cram school"-type afterschool program to prepare students for the hchs entrance examination.
I don't know if this is still a problem, but for a company that claims to be the official Rails host; they don't work closely with popular Rails related software.

For example a few months ago the latest version of Capistrano wasn't working on Joyent's Accelerator (Solaris). Joyent support acknowledged this, but it didn't sound like they even cared or planned to do anything, so I just canceled my account and I moved to Slicehost. It's not perfect but you get more for the money.
Eh. It's shiny and nice, but in the end, it's pretty useless. I lived with it for a month, then figured that it didn't do much good, and disabled it.

(I still enable it to show off to friends about how cool Linux is though, sometimes :D)
"... how many people living in the US know how to make gunpowder from scratch? Given enough time, I guess I could build a ... How would you survive if suddenly transported back to 1000 AD? ..."

Well I'd hope I'd be pushed forward a few hundred years into the late 12'th - early 13th century and dropped into Western Europe. The UK or France.

Why late 12th/early 13th century France or UK?

Well for one thing the "Hundred Years' War" is just starting and it probably is the most turbulent time in UK/French history and with this comes warfare and opportunity. It turns out this period of history is where the linage of the French House of Capet was broken and King of England (John - Henry III) had gone from owning more land than the King of France to loosing almost the lot.

The consequences of these new weapons meant
that the nobility was no longer the deciding
factor in battle; peasants armed with longbows
or firearms could gain access to the power,
rewards, and prestige once reserved only for
knights who bore arms.

But these were heady days for the English this is the time of the Longbow ( and by the way the 2 fingered salute favoured by those of English descent and a token to their weapons superiority ), the introduction of the cannon and the end of the era of chivalry, the introduction of Modern army, the introduction of the Magna Carta some 50-100 years prior, centralised government that had the authority to raise taxes & armies. So in terms of making your mark this was the era.

The first problem you'd have is language. I'd either have to bring a book (latin) or wing it on my language skills but where to learn latin? Anything but a classical education makes me stand out as an uneducated heathen. As for a job if you are fit enough you could either join up as a foot soldier but a more lucrative path might be to hack the warfare technology of the time and work on improving them. One problem at the time was training enough archers to use the longbow efficiently. It took a lot of training from an early age - all English boys from the age of 12 years had to train to use the longbow & all men from the ages of 15-60 carried such weapons.

I'd be looking out for Yeoman ~ http://en.wikipedia.org/wiki/Yeoman#Middle_Ages
I'd install my depenguinator. :-)
It's official: Match.com Abandons Paid Dating…
pidgin -- multiprotocol IM client

inkscape -- Vector Drawing

gobby -- collective editor

pgadminIII -- PostgreSQL GUI

EasyTAG -- mp3 tagging

dia -- diagram editor

GIMP -- photo editing (already installed most likely)

phatch -- batch photo manipulation

mercurial -- Distributed Version Control brings Meld which is a GUI merge program

emacs22-nox -- because I like it that way.

gnumeric -- because the numbers do matter.

python-${handy} -- my work environment has a swollen dependency tree :P

That's my list, but I'm a boring person who doesn't really play video games.
No, you're wrong. The thing is that there are two kinds of confusion that arise from Atwood's problem. The first kind of confusion comes from not understanding how probabilities work, which you discuss. The second kind -- which is what Paul Buchheit is talking about -- comes from noticing that the statement "I have two children, and one of them is a girl" can be parsed in two different ways. It can be parsed as, "I have two children, and at least one of them is a girl," or as "I have two children, and the gender of one of them is #{my_first_child.gender}." Despite what many commenters in this thread are saying, these are not the same.

That's the real problem here: the English language is inexact. The words that Atwood used to describe the scenario actually describe at least two mathematically distinct scenarios.

The Monty Hall problem suffers from this fact, too, but not as badly -- because both interpretations yield the same conclusion, namely, that you should switch doors. It's just that under one interpretation, you get a car 1/2 of the time, and under the other you get it 2/3 of the time. Also, under the interpretation that yields a car 1/2 the time, it's logically implied that the host is willing to open a door and reveal a car -- which most people use to rule out that interpretation, if only subconsciously.
Htop for monitoring system resources in real time, VirtualBox for running different OSes, Wine for some Windows games and apps, Deluge as a BitTorrent client. Conky is a great productivity booster and nice on the eyes too.
Then get the packages needed for playing all media files, and I think that's about it.
Oh, I forgot, Pidgin rlz.
That's the same argument the linux people made. Didn't seem to work.
Previously posted here: http://news.ycombinator.com/item?id=406277
Really, a problem is that almost everybody is right.

Yes - this is why I pointed out that in Jeff's post this riddle was used as a metaphor. Otherwise we could spend all our time bickering about the correct spelling of "colour" or other trivialities instead of addressing the interesting questions.

The interesting question in Jeff's post was the poor human understanding of probabilities.
I wouldn't install Amarok (avoid loading Qt in Gnome and vice versa). RhythmBox does not handle an iPod well if that matters for you, but Banshee does. Banshee relies on Mono.

Zim is a little-known note-taking tool that relies on text files and uses a Wiki format.

AbiWord and Gnumeric are good programs to have around when you don't want to start MS Office. Copy the .ttf and .otf font files from your Windows machine and install them in Linux if you want them available.

Inkscape is good to have around for drawing.

What else do you think you'll need?
I'll take that bet. Write the code, but be careful to implement my second algorithm exactly.
He makes a good case, but will anyone actually take it up?
I just realized, even your "correct" version, although more precise, is still underspecified and can't be answered. :)

Can you spot the problem?
Modern hebrew is somewhat different, but understandable to those that speak biblical hebrew. But I think in those days they did not speak it, but rather spoke aramaic.
Wow, maybe this works with politicians too?
You don't need a toothbrush or floss, just use a cloth and some salt (if you could get it, depends on exactly where you ended up).