Just because it's an Internet Draft doesn't mean anything at all (2014) - <AUTHOR> https://tools.ietf.org/html/draft-wkumari-not-a-draft-06 <comment><USER2> I contained my snarfing until:

"The ordinals 17, 42 and 6.12 are reserved to reduce confusion.

The ordinals 18 and 19 are reserved for the strings "Reserved" and "Unassigned" respectively.

Unfortunately the ordinal 20 was used by two earlier, competing proposals, and so can mean either "Color" or Colour". Implementations are encouraged to disambiguate based upon context."

At which point I audibly snarfed.

<comment> oh-4-fucks-sake Your snarfing was the impetus for my snarf. Ergo, not all snarfing originates from user Angostura, but all of user Angostura's snarfing has historically beget my snarfs.

</comment></comment><comment><USER3> "This all worked really well until approximately 1600BCE, at which time the fleeing Atlanteans brought mass quantities of lightly tanned eel leather into Egypt, causing the collapse of straight razor sharpening market."

I really admire people who can write a story like this off the top of their head.

<comment><USER4> Children love to listen to people with this skill.

<comment><USER5> I love to listen to people with this skill.

<comment><USER6> therefore...

<comment><USER7> Children are I

<comment><USER8> It does not follow

[https://en.wikipedia.org/wiki/Fallacy_of_the_undistributed_m...](https://en.wikipedia.org/wiki/Fallacy_of_the_undistributed_middle)

</comment></comment></comment></comment></comment></comment><comment><USER9> "Unlike most IETF efforts, this document is not embarrassed to clearly state that we are simply shuffling more stuff in while we have the editor open."

Classic.

</comment><comment><USER10> I thought that was already fairly well known via things like "IP over Avian Carriers".

<comment><USER11> But that's an RFC, so it carries (very slightly) more weight than an Internet Draft. In the real world, what matters is whether it's implemented: [https://www.blug.linux.no/rfc1149/writeup/](https://www.blug.linux.no/rfc1149/writeup/)

<comment><USER12> > In the real world, what matters is whether it's implemented

Yes, RFC 2324[1] is also serious business because it's implemented in the real world. Or at least I have implemented HTTP 418 I'm a teapot. (I've also seen gross violations where some APIs use HTTP 418 as their custom error code instead of complying with the RFC.)

[1] [https://tools.ietf.org/html/rfc2324#section-2.3.2](https://tools.ietf.org/html/rfc2324#section-2.3.2)

<comment><USER13> > _I 've also seen gross violations where some APIs use HTTP 418 as their > custom error code instead of complying with the RFC._

I know a lot of people disagree with the IETF's policy of imprisoning those who fail to comply with the RFC, but personally I don't think they go far enough.

</comment></comment></comment></comment><comment><USER14> To be fair, that's also true of RFCs as. (E.g., IP over carrier pigeon). But that doesn't really matter.

Take HTTP for example. The is no ISO standard, just a smattering of overlapping RFCs over the years with weird spellings (Referer) and ambiguities (GET request entity).

 _And the entire web is based on HTTP._

The quality of the "specification" documents is not high, nor very official, but it's the best we have, so people treat it as if it were.

<comment><USER15> I'd like to also share the legendary RFC 2795 for those not yet in the know: [https://tools.ietf.org/html/rfc2795](https://tools.ietf.org/html/rfc2795)

</comment></comment><comment><USER16> > From -02 to -03

> o This Change note was added. Nothing else changed.

This comment contains no commentary.

</comment><comment><USER17> In addition to the point made in the article, even some RFCs do not indicate "what the IETF thinks". And I'm not just talking about April 1st RFCs.

The IETF has the "Independent Submission Editor" stream of RFCs, which produces RFCs without getting IETF consensus. These RFCs are considered to be work "outside" of the IETF, but can still be published as an RFC.

A recent example is [https://tools.ietf.org/html/rfc8674](https://tools.ietf.org/html/rfc8674) from Mark Nottingham:

       The mechanism described in this document does not have IETF consensus
       and is not a standard.  It is a widely deployed approach that has
       turned out to be useful and is presented here so that server and
       browser implementations can have a common understanding of how it
       operates.

</comment><comment><USER18> RFCs are just a way for big corporations to collaborate on shared standards. It doesn't mean that other approaches can't become standards as well. It's kind of disturbing that RFCs seem to give projects automatic trustworthiness that they didn't actually earn.

<comment><USER19> At least more than one interested party thought about it, and documented the result. It might not be good, but it's worth evaluating to see if it's good enough.

Tldr: if you must send datagrams via pigeons, consider the rfc, then use an exfat microsd card.

</comment></comment><comment><USER20> But it's expired...

<comment><USER21> That's the sole reason you shouldn't use it as reference.

<comment><USER22> On the contrary; it permits it. Since its purpose was to prevant misattribution of internet-drafts to the ietf, we can surely now claim with certainty that the ietf teaches fake news about the demise of ancient egypt.

</comment></comment></comment><comment><USER23> > Each one of there tokens ...

What are "there tokens"? Aw come on. How do you expect me to take any of this seriously with grammatical mistakes like this?

<comment><USER24> Thank you for your review and comment. This oversight has been fixed, and new version posted: [https://www.ietf.org/id/draft-wkumari-not-a- draft-08.txt](https://www.ietf.org/id/draft-wkumari-not-a-draft-08.txt)

I'm planning on putting this on GitHub soon, so that issues can be filed, and, more importantly, pull requests submitted. Important work....

</comment></comment><comment><USER25> If HN guidelines are considered to allow it, I suggest tweaking the title here to say "Internet Draft" rather than just "ID", which is unambiguous in the original context (i.e., a thing that actually _is_ an Internet Draft) but not as an HN title.

<comment><USER26> Agreed, the title mislead me to think the article would be about unique identifiers (IDs) instead of internet drafts (IDs).</comment></comment>


Ask HN: What are the possible future opportunities for developers coding in C++? - <AUTHOR> As per current trends every other position is either for Python or Java developer. What are the possible future opportunities where C++ will still be used? <comment><USER2> It's still dominant in gaming (though losing share to Unity/C#), system software, and high-performance computing (of which quantitative finance is a significant subset).

I would recommend not optimizing for _number_ of job positions open, but for _desirability_ of job positions. You can only have one job anyway. If you would be unhappy doing Python or Java it doesn't matter how many open positions there are, you're not going to want any of them. Concentrate on finding a niche that you can get really good at, and then figure out who's hiring for it.

<comment><AUTHOR> Thank you for responding,

My thought process was, Larger the number of job postings, easier it would be to change companies (provided one has good enough coding skills).

Can you please elaborate on how to identify niche?

<comment><USER2> That's true, but you don't need hundreds of thousands of alternate companies. You're reasonably secure having 10+ that you could jump to. C++ is fine in that regards; where it becomes a problem is careers like aeronautical engineering or petroleum geology where you have a really specialized skillset that's used by only 2-3 dominant companies.

For finding a niche - basically you try out a bunch of different careers, problem domains, and skillsets, and specialize in one where a.) you enjoy the daily work involved b.) the people around you tell you you're pretty good at it and c.) you get paid reasonably well for it. It can take a fair bit of job- hopping and exploration to get there. Do this at the beginning of a career when it's expected of everyone.

</comment></comment></comment><comment><USER3> It's still a thing for low level, systems software development, and I predict will be for quite some time. Even popular projects like Tensorflow has a C++ backend. Other newer programming languages in the space like Rust have shown promising adoption, but C++ has Lindy effect for it.

<comment><AUTHOR> Thank you for responding, Can you suggest technology tracks, which current C++ Dev can migrate to without much effort. And still be relevant and in demand 5-6years down the line

</comment></comment><comment><USER4> I have seen a C++ quant position paying 500K a year. There are definitely opportunities.

<comment><AUTHOR> Link please

<comment><USER4> It was a job spec I was emailed.</comment></comment></comment>


Ask HN: Best ways to drown out invasive thoughts and focus on a task? - <AUTHOR>

There are many times for me when silence is more deafening than a loudspeaker. Okay fine that's hyperbole (mostly), but I often do like to have white noise of some kind (music, etc) in the background when I'm programming, planning, thinking, etc. It helps to restrain the random thoughts that fly through my head that take my focus away from what I'm doing. So my question is in what way(s) do you accomplish the "simple" task of focusing on one path when your mind seems to want to go in a thousand different directions? <comment><USER2> I like to give myself small, somewhat easy to achieve tasks that are subtasks of the larger task. Then I like to create time limits to accomplish those things. This keeps me focused on what I have to do…</comment>


A woman murdered her husband, and she got away with it - <AUTHOR> http://www.smashcompany.com/philosophy/this-woman-murdered-her-husband-and-she-got-away-with-it <comment><USER2> Interesting stat: women serial killers are supposedly very rare. But when found, they've killed from 6 to dozens of times.

I'm thinking they are not really rare, we just have a cultural blind spot. If that were so, then what do the known statistics say about the actual frequency? Fill in that bell curve.

I imagine many women serial killers can go a lifetime without getting caught.

</comment><comment><USER3> We never know the people that commit the perfect murder because no one even knows a murder has taken place. I would guess that there multiple perfect murders every year but the number is impossible to know! But I agree with her advice, only do it once if you want to get away with it.

<comment><USER4> Over 1% of all people commit suicide.

It's really hard to tell the difference between a suicide, someone forced into suicide, and outright murder.

I suspect there might be a lot more murders than statistics report.

<comment><USER5> So many murder victims never come forward to speak about the crimes committed against them. This is surely very massively under reported.</comment></comment></comment>


Think you understand Monty Hall? Try the Tuesday boy problem. - <AUTHOR> http://scienceblogs.com/evolutionblog/2011/11/the_tuesday_birthday_problem.php <comment><USER10> Doesn't this rest on the simple ambiguity in the phrasing?

> I have two children and one is a son born on a Tuesday.

If by that is meant:

> I have two children. Here is some information about one of them: son, born > on Tuesday.

Then the probability of the other child being a son is 1/2.

If on the other hand we mean:

> I have two children. One or more is a son. Exactly one of them was born on a > Tuesday.

Then we get the 13/27 probability.

In fact it doesn't seem reasonable at all to assume that _only_ one was born on Tuesday, while _at least_ one is a son. One single interpretation of 'one of them' must be applied to _both_ the gender and day of birth. Otherwise we're picking and choosing our interpretation on a whim.

edit: Colin appears* to think that what I've said here is incorrect, and I'd like to know why. I'm not a maths/stats person at all so am very keen to be re-educated on this matter.

* based on his now-deleted reply to ars which said "no, it doesn't, and no, you're not"

 _Important Edit Two:_

If I'm reading this right, I think the defender of the 13/27 solution would say:

No. We don't discount the possibility of both being tuesday-boys (TB), we just adjust the calculation so that it doesn't count (eldest=TB, youngest=TB) and (youngest=TB, eldest=TB) as two separate possibilities.

To which I respond:

Right, so it's not down to ambiguity. But shouldn't you also discount every other symmetrical pair such as (eldest=TB, youngest=WB) and (youngest=TB, eldest=WB) and thus return the odds to 1/2? Or does that not return the odds to 1/2?

<comment><AUTHOR> No, you shouldn't "also discount every other symmetrical pair", for exactly the same reason as there's a 1/36 chance of rolling double 6, but 2/36 chance of rolling a six and a one. It's all to do with labellings, and it's the most common source of error[1] in statistics.

[1] By "error" I mean calculations that then don't agree with the experimental results.

<comment><USER10> What about this:

I have two teenagers. One is a boy of 13.

Do we encounter a similar situation with regard to the odds of the second teenager being a boy?

edit: I'm thinking the odds are exactly the same, 13/27, by coincidence, as there are seven possible teen ages.

So then, what about this: One is a boy named George. Or One wears a black shirt. Or One likes chocolate.

Doesn't this mean that the more information we gain about the boy, the less likely it makes it that his sibling is a brother?

<comment><USER11> _Doesn't this mean that the more information we gain about the boy, the less likely it makes it that his sibling is a brother?_

More likely, but only if that information being true was a precondition for knowing about the boy in the first place. Take the following scenarios, assuming Alice knows Bob has exactly two children.

Alice: Do you have a son? Bob: Yes Alice: Pick one of your sons, and tell me the day of the week he was born Bob: Sunday

Here the day of week provides no additional information because Bob will always have an answer (like in Monty Hall, where Monty will always reveal a losing door), so the probability that Bob has two boys is 1/3.

Alice: Do you have a son who was born on a Sunday? Bob: Yes

Here having a son isn't enough; he also has to satisfy a condition that occurs with only 1/7 probability. Bob is more likely to be able to answer yes if he has two sons and thus two chances to satisfy that condition.

</comment></comment></comment></comment><comment><USER12> I've been thinking about this for an hour, and I'm now convinced that the author is wrong. The fact that we found out about one of the children _from the father_ means that all probabilities are not equal, even though they're treated here like they are.

The difference is between the information being offered, and determined independantly. I'll do this with the boy/girl problem, for simplicities sake.

If we ask a man if he has at least one boy, and he says yes, we can work out the chance the other child is a boy like so:

Assume all four possibilities are equally likely:

       BB
       BG
       GB
       GG

If we ask him if he has at least one boy, and he says yes, we effectively filter off GG, which brings the list down to:

       BB
       BG
       GB

Therefore, the chance of the other child being a boy is 1/3. Pretty straight forward.

However! Because the father offered the information on his own, it effectively turns it into the author's other problem, where the older child is a boy, find out the gender of the younger child.

The trick is that he's equally likely to give information about either of his children, therefore there are eight possibilities:

He gives information about child A:

       BB - <USER8>
       BG - <USER8>
       GB - <USER9>
       GG - <USER9>

He gives information about child B:

       BB - <USER8>
       BG - <USER9>
       GB - <USER8>
       GG - <USER9>

There are still 3 possibilities, but BB is twice as likely as the others, because if both children are a boy he's definitely going to reveal the gender of one of them as a boy; whereas if one is a girl and one is a boy, there's only a 50% chance he will.

       BB - 50%
       GB - 25%
       BG - 25%

So, the answer to this:

 _You meet a man on the street and he says, "I have two children and one is a son born on a Tuesday." What is the probability that the other child is also a son?_

Is 1/2

The answer to this:

 _A man has two children, and one is a son born on a Tuesday. What is the probability that the other child is also a son?_

Is 13/27

It's nitpicky, but I think the author should be very exact about this kind of thing, since he's trying to clear things up.

<comment><USER13> The issue here is with assumptions - you have made a different set of assumptions from the author, and hence are getting a different result.

A lot of people here are having similar issues, by misreading exactly what the initial proposition means.

Your reasoning above relies on the 'likeliness' of a man giving you the information, which is something that is not meant to be a part of the problem. Although it is phrased as a man 'telling' you something, that statement is really a metaphor for 'you determine the following piece of information, 100% truthfully'.

In particular, your explanation assigns agency to the man - that if he does in fact have a son, he may or may not choose to reveal the truth 'I have a son'. However it makes no allowance for the man lying - so you are assuming if he answers it will be truthfully, but you are allowing him the lie of omission.

Whilst there is nothing specific that rules out your interpretation, it is not what is intended. Read it instead as:

\----

There exists a man, A.

A has exactly two children.

The statement 'A has at least one Son, B' is true

What is the chance that the statement 'The Non-B child of A, is a son' is true?

\----

<comment><USER12> I agree that that is what the author intended to communicate. But I actually think that's a bigger stretch than my own interpretation - it changes how the information was determined, which has a definite impact on the outcome.

The reason why I posted was to suggest that the author should have worded it the second way, i.e.

 _A man has two children, and one is a son born on a Tuesday. What is the probability that the other child is also a son?_

Which leaves no doubt. I guess I didn't really make that clear enough with my original post.

</comment></comment></comment><comment><USER14> I found this post confusing and ambiguous, so I restated it in simpler terms, with pictures:

[http://mikeschiraldi.blogspot.com/2011/11/tuesday-boy- proble...](http://mikeschiraldi.blogspot.com/2011/11/tuesday-boy-problem-in- under-300-words.html)

<comment><USER15> Thank you for this. I slugged through the whole original article and felt like I was being beat up with words.

However, I still fail to comprehend how the "at least one is a boy" quirk maths out to a 1 in 3 chance that his second child is also a boy.

Taken literally, it does. I understand that, in a set of data, GB is different from BG. But for the sake of our comparison, the order the children were born in doesn't matter. We're seeking if the other child is a boy, or not.

In my mind, the bit about it being the younger or older sibling is irrelevant information. We're comparing gender, not age. Regardless of if she is the younger sister, or the older sister, she's still his sister, and therefore not a boy.

I think the introduction of age is convoluting the issue, unnecessarily.

I now standby, ready to be proven wrong. I'd really like to wrap my head around this one, but I must insist that the age information is irrelevant.

<comment><USER16> Probability is much less meaningful when you're not talking about large groups of repeated trials.

In the context of the article, imagine that you didn't do this just one time, but that you asked 100 fathers about the compostion of their children.

The question posed in the article is essentially, "Of those fathers who responded 'I have one son,' (which is likely 75 of the 100), how likely is it that they have another son, (which is likely 25 of that group of 75, or 1/3).

When the article talks about the father standing next to one of his children at random and the probability of another son being 1/2 at that point, it helps to imagine those same 100 fathers all standing next to their children. Of that group, you're not eliminating the fathers standing next to girls based on the way the situation is posed.

The English words used to describe each case make it much less clear which group of 100 people we're talking about.

Also, when we talk about one father and not a group of fathers, the 1/3 or 1/2 number is much less meaningful. This is where insurance companies make their money (ideally). It's impossible to predict whether a single person will die in a car accident over their lifetime, and any number is essentially a guess. But it's very easy to predict that, say, 1 in 50,000 people will.

</comment></comment></comment><comment><USER17> As the currently top voted comment does not get it, I try to intuitively explain the paradox.

No, it is not ambiguity of language. It says formally:

I have two children. There exists a child of mine who is (boy and born on tuesday).

And yes, the probability of the other child being a boy is 13/27.

To understand this, try a more extreme case:

When a child is born we generate a random number: rnd(1billion)

Now the man says:

'I have two children. There exists one of them which is boy with generated id=456765234'

As we can see, the probability of the other child being a boy approaches 1/2 as we increase the bound of our random number!

Why is this intuitively?

Because by using a very specific id we are closer and closer to specifying one of the boys, as the probability of the id not being unique decreases. We are closer and closer to saying this:

'Randomly pick one of my children. He is a boy. What is the probability of the other being a boy?'

Yes, that would be 1/2.

Edit.: Seriously downvoting this??? For most commenters the correct result was not intuitive. (It was not intuitive for me at first also). I tried to make this intuitive to them. (a bit deeper than usual paradxes though) Or do you still think the 13/27 result is not correct? In that case you are fighting mathematical truth with the downvote button.

Edit: Thanks, corrected probability from 2 to 1/2

<comment><USER18> Why can't the other boy also be born on Tuesday?

<comment><USER17> The other can also be born on Tuesday. (generated id = 1 in rnd(7)) And the other can also have a generated id = 456783123 in rnd(1billion). But as the bound of the rnd is bigger and bigger, the probability of that approaches to zero. So as we know more and more information of one of the children, we are closer and closer to simply uniquely identifying him, so the probability of the other being a boy approaches 2.

<comment><USER18> If both can be born on Tuesday then telling me one was born on Tuesday does not uniquely identify him! It's not unique if both can do it.

And since it's not unique the rest of your analysis is based on a faulty assumption.

(BTW I did not downmod you, in case you were wondering.)

<comment><USER17> It is about specifying a child, and then saying it is a boy.

The one extreme is: one of my children is a boy. in this case the other is a boy with 1/3 probability.

The other extreme is: One of my children has a national unique id=... He is a boy. The other is a boy with 1/2 probability.

And other cases are in between. The more information you provide on the first child (the less chance there is that the other can have the same property, the more close you are to 1/2.

Of course in the rnd(7) example we are in-between:

1/3 < 13/27 < 1/2

<comment><USER18> "the less chance there is that the other can have the same property"

No! That is not true! The two events are independent, specifying information on one has zero impact on the other.

<comment><USER19> They are independent, but you get information about both ("One of _them_ is a boy."), therefore p=1/3.

If you say "the older is a boy" then you have a statement about one son and no information whatsoever about the younger one, therefore p=1/2.

<comment><USER18> "One of them is a boy." is a completely different scenario and no one is arguing about it. (BG, GB, BB, GG - by saying one is a boy you exclude GG leaving 1/3.)

In this case we are asking if the other is a boy NOT if the other was born on Tuesday.

<comment><USER19> Ah, sorry, I misunderstood your question.

You are asking, why the information "one is born on Tuesday" says anything about the gender or birthday of the other, right?

More specificaly, this:

> _Let us first assume that it is the older child who was a son born on a > Tuesday. In this case the second child could be either of two sexes, and > could have been born on any of seven days of the week, for a total of 14 > possibilities.

> Now let's suppose it is the younger child who was a son born on a Tuesday. > Then the older child could, again, be either of two sexes and could have > been born on any of seven days of the week, again providing 14 > possibilities. Added to our original 14 that would seem to give 28 > possibilities.

> But be careful! One possibility got counted twice. Specifically, the one > where both children are boys born on Tuesdays. So really there are only 27 > possibilities. And since 13 of them involve the second child being a boy, > the probability would be 13/27_.

Maybe it helps, if you first imagine _all_ 196 (2 * 2 * 7 * 7, think of four 7-by-7 tables [draw them, it helps a lot ;)]) possibilities. Eliminate 49 of them where both are girls (one of the four tables) and you have 147 possibilities/cells left. Then, in each of the two BG and GB tables leave only one row/column, eg. eliminating another 2 * 6 * 7=84 possibilities.

Now comes the interesting/tricky part: The last case/table, where both are boys contains only 13 possible cases (instead of 2 * 7)! Imagine a 7-by-7 table, where each row and column corresponds to a day. Mark all the cells which are not in a Tuesday-row or a Tuesday-column, eg. eliminate all posibilities where none of the two boys are born on a Tuesday. This eliminates another 49-13=36 cases.

So, we have a total of 196-49-84-36=27 cases, 13 of which "the other is a boy" and 3/27=1/9 cases where "the other is born on a tuesday".

I hope this makes somewhat sense. Once I've drawn all the possibilities and marked all the impossible ones, it became a lot clearer.

<comment><USER19> ADDENDUM: The tables:

           A: Boy                     A: Boy
           M T W T F S S              M T W T F S S

     B M   . 1 . . . . .        B M   . 1 . . . . .
       T   1 1 1 1 1 1 1          T   . 1 . . . . .
     B W   . 1 . . . . .        G W   . 1 . . . . .
     o T   . 1 . . . . .        i T   . 1 . . . . .
     y F   . 1 . . . . .        r F   . 1 . . . . .
       S   . 1 . . . . .        l S   . 1 . . . . .
       S   . 1 . . . . .          S   . 1 . . . . .

           A: Girl                    A: Girl
           M T W T F S S              M T W T F S S

     B M   . . . . . . .        B M   . . . . . . .
       T   1 1 1 1 1 1 1          T   . . . . . . .
     B W   . . . . . . .        G W   . . . . . . .
     o T   . . . . . . .        i T   . . . . . . .
     y F   . . . . . . .        r F   . . . . . . .
       S   . . . . . . .        l S   . . . . . . .
       S   . . . . . . .          S   . . . . . . .

     total: 196
     of which are possible ('1'): 27
     of which 'the other is a boy': 13
       (all the ones from the upper left table)
     of which 'the other child is born on a tuesday': 3
       (the T/T-cell of each table)

</comment></comment></comment></comment></comment></comment></comment></comment></comment></comment><comment><USER20> It's fun to reason these things out, but it's easier and faster to simulate, at least at first.

      import random, time, collections, pprint

      sample = collections.defaultdict(float)

      now = time.time()

      known_child = ('M', 2)

      while sum(sample.values()) < 100000:
          genders = [random.choice('MF') for dummy in '..']
          birthtimes = [random.uniform(0, now) for dummy in '..']
          birthdays = [time.localtime(t).tm_wday for t in birthtimes]
          gendertimes = zip(genders, birthdays)
          if known_child in gendertimes:
              gendertimes.remove(known_child)
              sample[gendertimes[0]] += 1
              if (sum(sample.values()) % 10000) == 0:
                  print sum(sample.values())

      males,females = [sum(c for (g, t), c in sample.items() if g == gender)
                       for gender in 'MF']

      print males / (males + females)

Result when I ran this was .4816, approximately equal to 13/27.

</comment><comment><USER21> The more sons you have, the more likely that one of them is born on a tuesday. Thus, if you take all the two-child families with at least one son, and eliminate the families without a son born on tuesday, the two-boy families are more likely to remain than the one-boy families, and you will end up with a higher proportion of two-boy families than before.

Simple.

(edited)

<comment><USER22> _Simple._

And wrong. Note that the correct answer is 13/27 probability of a boy, which is less, not more, than 50%.

<comment><USER21> Sorry, I should have said a higher proportion of two-boy families, not a higher proportion of boys. 13/27 is more than 1/3, which is the proportion of two-boy families before you eliminate the families without tuesday boys.

</comment></comment></comment><comment><USER23> I stopped caring about 'paradoxes' ever since I understood there's no isomorphism between pure mathematical concepts and human language.

<comment><USER24> The paradoxes are important in highlighting the ambiguities in our language.

The annoying aspect is when someone uses a paradox to show off how mathematically clever they are, instead of to show how ambiguous language is. As XKCD illustrates: <https://www.xkcd.com/169/>

</comment></comment><comment><USER18> I hate this one because while it says:

      "I have two children and one is a son born on a Tuesday."

It actually means:

      "I have two children and only one of them is a son
       born on a Tuesday."

You are supposed to just assume this modification.

<comment><USER25> No I don't think that's true. Bear with me :-)

There are 14 possible permutations for a child

Mon-Sun Girl

Mon-Sun Boy

which for two children gives a total of 28:

Child 1 is Boy, born Mon-Sun

Child 1 is Girl, born Mon-Sun

Child 2 is Boy, born Mon-Sun

Child 2 is Girl, born Mon-Sun

Note that we haven't said which child is 1 and which is 2, and in fact we don't know because we haven't been told - this is the important bit.

So, for our unknown child to be a boy, it must be one of the following 14 permutations:

unknown child is Child 1, boy, born Mon-Sun

unknown child is Child 2, boy, born Mon-Sun

but one of those permutations is already taken by our known Tuesday boy, so we have to remove one of the Tuesday permutations leaving 13 possible outcomes out of 27. Note that one of those 13 outcomes is 'unknown child is son born on Tuesday' - it's perfectly valid to have both sons born on a Tuesday.

Note also that we can't say which permutation we're removing until we know which is Child 1 and which is Child 2, just that one of them is taken.

If the original statement were phrased as '... the older child is a son born on a Tuesday' then you would have a constraint on which was Child 1 and which was Child 2 and then the probability would be 1/2 as expected because you would know up front that you were entirely discounting, say, Child 1, AND that the removed Tuesday permutation also belonged to Child 1.

But I stand to be corrected!

<comment><USER18> First, saying Mon-Sun is confusing almost everyone since most people start the week on Sun, not Mon. (Even in Europe Christians start the week on Sunday.)

In any case, as I replied here <http://news.ycombinator.com/item?id=3290118> you can not remove the duplication! It's two different situations, even though they may appear the same.

<comment><USER25> ajanuary explains the duplicates problem nicely here: <http://news.ycombinator.com/item?id=3290185> so I won't double up.

I've spent the last hour and a half wrestling with the same clash between maths and intuition that you're experiencing so I understand your frustration - 13/27 really is the right answer though.

<comment><USER18> He explains it, and he's wrong.

Look, I understand your intuition wants you to remove duplicates "They are the same!". But you should resist, because doing that gives incorrect results.

<comment><USER25> On the contrary - I'm saying that 'removing the duplicates' is _counter_ intuitive and that's why you're having trouble with it, the same as I did.

Besides: please re-read my original post - I didn't mention anything about removing duplicates, and in fact chose to explain the problem in a different way precisely because the duplicate removal thing was so difficult for me to grasp sufficiently to be able to explain it.

Ask yourself this: where does the original 28 come from? One of those 28 permutations appears to be 'Child 1 is Tuesday boy' and 'Child 1 is Tuesday girl'. If you can answer that then you should be able to understand the whole thing.

(edited for clarity)

</comment></comment></comment></comment></comment></comment><comment><USER26>
        Let's try a simpler problem. Suppose we know that a
        certain man has two children and we also know that the
        older one is a boy. In this case we would say that the
        probability that the other child is a boy is 1/2. After
        all, the sex of one child is independent of the sex of
        the other child. That the older child is a boy has no
        bearing on the sex of the younger child.

        Now suppose we know simply that a man has two children
        and that one of them is a son. This time we would reason
        that there is no possibility that the person has two
        girls. It follows that the sexes of his two children,
        ordered from oldest to youngest, are either BB, BG or GB.
        Since these cases are equally likely, and since only one
        of them involves having two boys, we would say the
        probability that the man has two boys is 1/3.

Maybe I'm missing something, but this seems fundamentally wrong. Pr(two boys | older child = boy) is not equal to Pr(two boys | one+ child = boy)? Why is time so special? Could we not order them based on their height, and assert Pr(two boys | taller child = boy) = 1/2. Or, if there were a scale of masculinity, order them based on that and assert Pr(two boys | manlier child = boy) = 1/2, where manlier child = boy <==> one+ child = boy, so Pr(two boys | manlier child = boy) = Pr(two boys | one+ child = boy) (contradiction).

<comment><USER27> For a randomly selected family with two children, there are four possible boy/girl combinations: B B, B G, G B, G G

In the first case we are told that the older child is a boy. This leaves only two cases: B B, B G Therefore, there is a 50% chance the second child is a boy.

In the second case, we are told only that [at least] one child is a boy. This leaves three possibilities: B B, B G, G B Therefore, the probability that both children are boys is 1/3.

Enumerating possible states of the world like this is the fundamental insight you need to have to be able to understand these types of problems - but it does take a while to get used to!

<comment><USER26> But you are assuming that each of those three possibilities has equal probability; can you explain the rationale for that? (it is clear why BB, BG, GB, and GG have equal probability in the unrestricted case, but less clear why BB, BG, and GB have equal probability in this restricted case)

Besides, this is just a rephrasing of the original article's argument, and doesn't counter mine at all. I am open to the possibility that there is a flaw in my argument, but where is it?

<comment><USER27> So you say: "it is clear why BB, BG, GB, and GG have equal probability in the unrestricted case"

The restricted case is just the unrestricted case + one additional bit of information, that is, you're told that GG is not an option. This eliminates GG from the unrestricted case, but says nothing more about the probabilities of the other options. So the probabilities stay equal, although they now equal 1/3 each (if you eliminate options, the remaining options all become more likely).

What you're missing is this: The statement "the older child is a boy" has more information than the statement "one of the children is a boy". The first statement allows you to eliminate two options (GB and GG), while the second statement only allows you to eliminate one option (GG).

The "older" part is not fundamental to the problem. Equally, the statement "the taller child is a boy" has more information than "one of the children is a boy". The problem with this is that probabilities for height are not so friendly like the 50/50 probabilities for birth order (e.g., boys are likely to be taller than girls, older children are taller than younger, etc), which introduces unnecessary complexities to a logic problem. So that's why birth order is used for these types of puzzles.

</comment></comment></comment></comment><comment><USER28> For the people who don't believe this, here's a Python program:

        x = [(c1,c2,d1,d2)
                for c1 in ["B","G"]
                for c2 in ["B","G"]
                for d1 in [0,1,2,3,4,5,6]
                for d2 in [0,1,2,3,4,5,6]
                if (c1 == "B" and d1 == 1) or (c2 == "B" and d2 == 1)]

        num = sum(1 for (c1,c2,d1,d2) in x if c1 == "B" and c2 == "B")
        denom = sum(1 for _ in x)

        print("%s/%s" % (num,denom))

</comment><comment><USER29> If you generalize "born on Tuesday" to a generic attribute, with probability p (equal for boys and girls) it becomes easier to see what's going on. For brevity, let's say people with the attribute are positive and people without are negative.

There are seven (ordered) possibilities involving at least one positive boy, and we'll subdivide them into two subgroups: B+B- B-B+ B+G- G-B+ / B+B+ B+G+ G+B+. The important thing to note is that _within each group the outcomes are equiprobable_.

If p is near 1, then the first group has almost zero probability and we have ~1/3 chance of two boys. If p is near 0 then the second group has almost zero probability and we're left with ~2/4 chance of two boys.

Intuitively, if p is near 1 then the statement "I have at least one positive boy" is almost equivalent to "Both my children are positive, and I have at least one boy" (group 2, 33% chance). If p is near 0, then the statement is almost equivalent to "I have exactly one positive boy" (group 1, 50% chance).

</comment><comment><USER30> I understand thanks to a comment I found here: [http://helives.blogspot.com/2010/07/tuesday-child- puzzle.htm...](http://helives.blogspot.com/2010/07/tuesday-child-puzzle.html)

</comment><comment></comment><comment></comment><comment></comment><comment></comment><comment></comment><comment>

Unfortunately, these questions you ask are ambiguous, and it is the failure to recognize how they are ambiguous that causes the results to seem unexpected. Consider two versions of what led up to the first statement:

Case #1: A father is chosen at random. He is given a slip of paper as he is led onto a stage. The paper says "Pick one of your children. Tell the audience the number of children you have, the chosen child's gender, and the day of the week on which it was born."

Case #2: A father is chosen at random from all fathers who have two children, including one boy born on a Tuesday. He is also ushered onto a stage and given a slip of paper that instructs him to tell the audience the criteria used to select him.

Now shift scenes. You are in the audience when a man is ushered onto the stage. He looks at a slip of paper, thinks a moment, and says "I have two children and one of them is a boy born on Tuesday." What is the probability that he has two boys?

The answer to the question depends on which case applies to the man you listened to. In Case #1, it is 1/2. In case #2, it is 13/27. Your simulation only covered the second case. To get the first, after you have two children, flip a coin to see which one the father will tell about. If it is not a Tuesday Boy, don't keep that trial even if the other child is a Tuesday Boy. You will find that the 27 cases where you have a Tuesday Boy reduce to 14 (just over half, since one father didn't need to flip the coin), the 13 where you also have two boys reduces to 7, and the answer is exactly 1/2.

If you simulate the simpler problem, where you don't worry about the day of the week, the answers are 1/2 and 1/3 for the two cases, respectively. The reason 13/27 seems unintuitive, is because the fact that a Tuesday Boy was REQUIRED in the second case is not intuitively obvious from the statement "one of them is a boy born on Tuesday." In fact, as you point out, the puzzle could equally well be named after either of your two children, which is probably two different names. You choose one, just like the father in case #1, so the better answer to your question is 1/2, not 13/27. It is still ambiguous, but there is no valid reason to assume that case #2 applies.

</comment><comment><USER31> When in doubt, use brute force:

        1BT 2BM    1BM 2BT
        1BT 2BT    1BT 2BT <-- Counted twice
        1BT 2BW    1BW 2BT
        1BT 2BR    1BR 2BT
        1BT 2BF    1BF 2BT
        1BT 2BS    1BS 2BT
        1BT 2BU    1BU 2BT
        1BT 2GM    1GM 2BT
        1BT 2GT    1GT 2BT
        1BT 2GW    1GW 2BT
        1BT 2GR    1GR 2BT
        1BT 2GF    1GF 2BT
        1BT 2GS    1GS 2BT
        1BT 2GU    1GU 2BT

I think the issue people are having is that they want to distinguish between the two instances of '1BT 2BT', but it doesn't work like that. Let's say I numbered each of the possibilities written above 1 through 28. If I handed you a piece of paper with '1BT 2BT' written on it, could you tell me which number that corresponded to? No - it would be one of two numbers - so the numbering is additional information not given in the problem statement.

<comment><USER32> Alternatively, suppose we label the combinations of child-day BM, GM, BT, GT ... BU, GU (14 items). We have a bucket with 2 of each of these combinations, as there are 2 kids (total 28 items). The problem states that we have taken one "BT" item out of the bucket (so 27 items left), and are asking how many "B*" items are left in the bucket (13).

The confusion arises because one can consider the same problem with replacement, putting back the BT item in the bucket before picking a second time. It's something that's not clear if u are not thinking of enumeration.

<comment><USER33> What would the question have to be to make the following the answer?

 _Suppose we label the combinations of child-day BM, GM, BT, GT ... BU, GU (14 items). We have two buckets which both contain a copy of each combination (total 28, 14 in each bucket). The problem states that we have taken one "BT" item out of one bucket, and are asking how many "B_ " items are left in the other bucket (7 out of 14). _

<comment><USER32> That would be two parents having one child each, one of whom says his only son was born tuesday, and asking what 's the probability the other guy has a son.

</comment></comment></comment></comment><comment><USER34> Sometimes I hate these types of problems - though they're quite fun to argue about - because though they seem to be simple, straightforward enumeration problems, the "right" answer depends on assumptions about how the information that you've got is obtained, and what the other possible pieces of information you could have obtained are.

Here's the thing: nobody needs to see how you obtained your answer, we're all smart enough to enumerate things, so don't bother; similarly, leave out the equations, they're simple enough, and that's not where anyone falls over. If you want to argue productively about this type of problem, you need to explain _why_ you enumerate the possibilities the way you do, not _how_.

And actually, I think the article goes through this problem pretty well, as mentioned there it hinges on two questions:

1) In this "random sampling", was "girl" a possible answer? Or did we restrict the sample pool to only people with boys, and only let them reveal that they had a boy?

2) Similarly, was any day other than "Tuesday" a possible answer?

Once people agree what the "obvious" answers to these questions are, disagreements tend to evaporate very quickly, and the enumerations/equations solve themselves. Unfortunately these assumptions are almost never spelled out in the problem, which is why these damn problems keep confusing people...

</comment><comment><USER35> "You meet a man on the street and he says, "I have two children and one is a son born on a Tuesday." What is the probability that the other child is also a son?"

The fact that one of the sons is born on a Tuesday, is blonde, has freckles, got an A+ on his math paper is irrelevant to the gender of the second son. The author's entire reasoning misses the entire point of the Monty Haul paradox where Monty Haul specifically reveals a door known _not_ to have the Goat, thereby immediately modifying the probabilities of the remaining door.

In this "Tuesday Boy Problem" - no such selection takes place. There is no paradox. There is a 50% chance that the other child is a boy and a 1/7 chance that they were born on a tuesday (or a monday, wednesday, etc...).

Note - The wikipedia article on this topic does a much better job discussing the ambiguity involved in asking the question - <http://en.wikipedia.org/wiki/Boy_or_Girl_paradox>.

The sad part of this, is that if you had _selected_ a family in which at least one son was born on a tuesday, then you would have modified the probabilities of the other child being born a son - but no such selection was done here, therefore no probabilistic impact on the chance of the other child being a son.

<comment><USER29> There is a shorthand and implied understanding in mathematical word problems (else they would be formulas!). As soon as you ask "what is the probability" you are implying either a sampling/generative process, or a subjective (e.g. Bayesian) probability framework. I think it's clear this is the former case.

The generative model implied for each child is: pick uniformly from boy/girl, and pick uniformly from Mon-Sun. The generative model for the father is: generate two children.

This generative process has a well-defined outcome distribution and it is completely reasonable to ask "what is the probability of generating an outcome with two boys, given that you generated an outcome with a Tuesday boy?"

</comment></comment><comment><USER36> Wait. What? The author says there can only be one BB but that there can be both GB and BG?

What he's doing here is saying that birth order functionally doesn't matter if the sibling is a boy, but it _does_ matter if it's a girl. How is this correct?

If you keep comparing apples to apple you get:

      Older Boy / Boy
      Boy / Younger Boy
      Older Girl / Boy
      Boy / Younger Girl

And we're back to a 50% chance that the other child is a boy.

<comment><USER37> Since he has two children, you know first off that these are all equal chance historically:

BB BG GB GG

Now since you know the child is a boy, it eliminates the fourth option. So now we have these possibilities:

BB BG GB

In only one of these is the other child a boy, so the chance is 1/3.

<comment><USER36> This explanation makes a ton of sense. I get it now. Thank you.

<comment><USER37> Also I don't think the exact day of birth being Tuesday makes one bit of difference to the gender. For example, if you were to say the known boy was born crying, and the chance of this is 70%, it doesn't affect the gender of the other children. It's just useless trivia.

<comment><USER28> That's not true. It does affect the probability of the other child being a boy just like being born on Tuesday does.

</comment></comment></comment></comment></comment><comment><USER38>
      A small simulation in Python

      from random import randint
      oneBoy=0
      twoBoys=0

      # 0 = boy, 1 = girl
      for i in range(10000):
          s1 = randint(0,1)
          s2 = randint(0,1)
          if s1 * s2 == 0:  # Here is at least one boy
              oneBoy = oneBoy+1
              if s1 == s2:  # Here are two boys
                  twoBoys = twoBoys+1
      print("Two Boys")
      print(float(twoBoys)/float(oneBoy))

      # As expected the result is near 1/3.

      oneBoyT=0
      twoBoysT=0
      #days 0=Monday, 1=Twesday ...
      # (0,1) means (sex,day) = a boy was born one Twesday

      for i in range(1000000):
          s1 = randint(0,1)
          d1 = randint(0,6)
          s2 = randint(0,1)
          d2 = randint (0,6)
          if (s1,d1)==(0,1) or (s2,d2)==(0,1):
              oneBoyT = oneBoyT+1
              if s1 == s2:
                  twoBoysT = twoBoysT +1
      print("Two Boys in Twuesday")
      print(float(twoBoysT)/float(oneBoyT))

      # The simulation gives a result near 1/3,
      # this is a hint to prove that 13/27 is incorrect
      # under the assumption that the population sex and
      # day are independent, and with probability 1/2 and 1/7

      # if you want to convince me otherwise, I'll be
      # glad to see the code to generate the population
      # and the estimated probability.

</comment><comment> adam-a > I have two children. Child A is a boy, born on a Tuesday, what is the > probability that child B is a boy?

We have no knowledge of child B so the probability is even for it being a boy or a girl.

> I have two children, at least one of them is a boy who is born on a Tuesday. > What is the probability that I have two boys?

We have incomplete knowledge of both children, we are constraining a probability space in 2 dimensions (i.e. the 2 children) rather than refining it down to 1 dimension as before. In this case the probability is 13/27 as these tables (<http://news.ycombinator.com/item?id=3290349>) nicely show.

When the father says "one is a son born on a tuesday" this can be read as him selecting a child and then asking you about the second or as giving you some information that can apply to either child and then asking you about both.

In my opinion the language used leads much more easily to the first interpretation, this is the reason surely for the confusion.

</comment><comment><USER16> The crux of the issue is much better illustrated by the simplified problem where if a man tells you one of his kids is a boy, the other child is a boy in 1/3 cases. That's intuitive looking at the possibilities:

BG GB BB

Where this analysis gets confusing is when you say that if you meet the man with one of his kids at random and it's a boy, the probability changes to 1/2. The reason is in that case one of the possible outcomes was indeed GG, even if the child you met was a boy. The difference is how much knowledge you had about the situation prior to making your measurement of the outcome.

If that doesn't make your head spin even a little you're not really human.

I was able to make peace with these problems when I read about the Two Envelopes Paradox and realized that it's not really possible to pick a random integer, because by picking a random integer you're essentially limiting the domain of integers you've picked from to a finite one. If you can wrap your head around that it might help you save your sanity.

</comment><comment><USER39> I finally understand it.

Here are my events (taking 2 children as given):

      B = I have a boy
      BT = I have a boy and he was born on Tuesday
      2B = I have 2 boys
      B+G = I have a boy and a firl

Using Bayes' Theorem:

      Pr(2B|BT) = Pr(BT|2B)Pr(2B)/c
      Pr(B+G|BT) = Pr(BT|B+G)Pr(B+G)/c
      where c = Pr(2B|BT) + Pr(B+G|BT)

      Pr(BT|2B) = 1/7 + 1/7 - 1/49 = 13/49
      Pr(2B) = 1/4
      Pr(BT|B+G) = 1/7
      PR(B+G) = 1/2

So

      c = 13/49 * 1/4 + 1/7 * 1/2 = 27/49
      Pr(2B|BT and 2C) = (13/49 * 1/4) / (27/49) = 13/27
      Pr(B+G| BT and 2C) = (1/7 * 1/2) / (27/49) = 14/27

They main reason Pr(2B|BT) is around 50% is that Pr(2B|BT) is proportional to Pr(BT|2B) while Pr(B+G|BT) is proportional to Pr(BT|B+G) and Pr(BT|2B) is about 2 * Pr(BT|B+G).

It's much more likely you have a boy born on Tuesday given that you have 2 boys (rather than you have a girl and a boy) so it's more likely that you have 2 boys given that we know you have a boy born on Tuesday.

</comment><comment><USER40> P(two boys, at least one on tuesday) = 1/4 (1 - 6/7 6/7). The 1/4 is the probability of two boys, and the 1 - 6/7 6/7 is the probability at least one is born on tuesday.

P(one boy, one girl, boy on tuesday) = 1/2 * 1/7. The 1/2 is the probability of having one boy, one girl, and the 1/7 is the probability that the boy was born on tuesday.

The man can make his statement if either of the above is true, and they are disjoint, so their sum gives the probability that he has two children, one a boy born on tuesday.

The ratio of the first to the second is the probability that both are boys. Plug in the numbers and you indeed get the 13/27 the article claims.

</comment><comment><USER41> p(2s\T)=p(2s & t)/p(T)

p(2s & T)=1/4 _(13/49)

p(T)=1/4_(13/49)+1/2*(1/7)

p(2s\T)=(13/49)/(13/49+14/49)

p(2s\T)=13/27

</comment><comment><USER42> To answer the question posed by the title: no, I didn't think I understood Monty Hall, but thanks to this article I'm pretty sure I do now. This is a good explanation and analysis.

</comment><comment><USER43> If you get that far down in the comments, you should also read why I think all solutions given here and by the author are wrong: <http://news.ycombinator.com/item?id=3291009>

</comment><comment><USER14> This post would have been much better if the author had used more precise language. I still don't know whether the assertion being made by the father is that _at least_ one of his children is a son born on Tuesday, or _exactly_ one is.

</comment><comment><USER44> Scott Aaronson has a really good article about the anthtopic principle and conditional probability.

<http://www.scottaaronson.com/democritus/lec17.html>

</comment><comment><USER45> How would the solution change if the problem was stated as follows: 'You meet a man on the street and he says, "I have two children and one is a son born in March." What is the probability that the other child is also a son?'

<comment><USER14> Or, "...one is a son born in an even-numbered month"

</comment></comment><comment><USER46> I have two children. One of my children is a son born on a Tuesday. Of course, my wife is still pregnant with the 2nd, but she will be thrilled to know there is a better than average chance she is having a girl!

</comment><comment><USER47> "If you surveyed all such families, you would find that roughly 13/27 of them have two boys." _roughly_ 13/27? How rough are we talking, maybe it's roughly 13/26 instead.

<comment><USER48> The degree of "roughness" depends on the number of families surveyed. The more there are the closer to 13/27 you'll get.

</comment></comment><comment><USER49> > Now suppose we know simply that a man has two children and that one of them > is a son. [snip] It follows that the sexes of his two children, ordered from > oldest to youngest, are either BB, BG or GB. Since these cases are equally > likely, and since only one of them involves having two boys, we would say > the probability that the man has two boys is 1/3.

Errr. except these cases aren't equally likely - because the boy we know about could be either of the boys in the BB scenario, but only one either of the other two. So the probability is still 1/2.

<comment><USER27> Since the constraint simply says that at least one child is a boy, we don't need to distinguish between two types of BB.

This is a curious misconception, by the way. The typical failure mode I see on these questions is people having difficulty accepting BG and GB as different possibilities.

<comment><USER49> If we are determined to look at order of birth (ie. have a BG and GB) then we should consider all cases by order of birth, so where 'B' represents the boy we know and 'b' or 'g' represents a child we dont, and the first character represents the first child, and the second the second childe - we have:

Bb, bB, Bg, gB

50%.

<comment><USER27> Imagine a similar problem but with red and blue poker chips. Say, for example, that I have a bag and I pull out two chips, one at a time.

In this problem, would you still try to distinguish the two identical red poker chips using your logic?

<comment><USER49> Okay. To respond to both of you - I have put this in programming just to check, and I think you are taking a different inference from the question than I am.

Under your inference, the man wouldnt have mentioned anything unless he had at least one male child. (in which case you can say the GG scenario is gone, but GB BG and BB are equally probable)

Under my inference, the man just told me the sex of one child at random.... (in which case BB is twice as probable as GB or BG - where he could have equally said 'i have at least one girl')

That sound reasonable to you? I have it in ruby form if you are interested :)

The blogpost linked to by someone above (<http://blog.tanyakhovanova.com/?p=221>) uses this explanation, which is very different (to me) than the one in the main link, and I can see why this gets to 1/3:

"A father of two children is picked at random. If he has two daughters he is sent home and another one picked at random until a father is found who has at least one son."

<comment><USER27> "Under your inference, the man wouldnt have mentioned anything unless he had at least one male child. (in which case you can say the GG scenario is gone, but GB BG and BB are equally probable)"

No. I'm just assuming he has two children, and randomly mentions something about one of them. The GG scenario is only eliminated _after_ he makes his statement, because we then know he has at least one boy.

<comment><USER49> Ah, then I do think you have an error of logic.

Put it this way. before he says it, we have GG, GB, BG, BB

after he says "I have a child that is [MALE OR FEMALE]" we have (where the capital letter is the child whose sex has been mentioned, and the lowercase letter is the other child):

Gg, gG, Gb, gB, Bg, bG, Bb, bB

So if he has said the sex is male, then we have four combinations left:

gB, Bg, Bb, bB.

Understand that we go to more scenarios (8) based on which child is mentioned, before we go to fewer. Actually the order of the children is something you can and should ignore, however as you are holding on to it, I show it this way....

<comment><USER27> I'm afraid this is wrong - you shouldn't distinguish between Bb and bB. In this problem, they are not different states, so counting them messes up your probability calculation.

Someone had a nice link higher up: [http://mikeschiraldi.blogspot.com/2011/11/tuesday-boy- proble...](http://mikeschiraldi.blogspot.com/2011/11/tuesday-boy-problem-in- under-300-words.html)

</comment></comment></comment></comment></comment></comment></comment></comment><comment><USER50> The last Mythbusters episode put Monty Hall to the test and passed. I have to say it was the first time I truly understood why Monty Hall works.

</comment><comment><USER51> I think you a few words. I have only 1 son who was born on a Tuesday. Basing this on ambiguity of phrasing is not novel, or interesting.

</comment><comment><USER52> I have a son born on xDay. What is the probability that my next kid will be a son?

I dont get Monty Hall :(

<comment><USER53> The Tuesday Birthday problem is related to you not having info about the order leading to extra possibilities that you don't intuitively consider. Like in the simple example, if one son is a boy, probability of other being a boy is 1/3rd because the info you have the sets available could be BB, BG or GB. But if the younger son is a boy, then the GB possibility is removed, so it's 1/2 on the older son - BB or BG.

In your case, your younger kid is a son born on xDay. If you assume you will have another kid, chances on being a son are still 50%. It only gets interesting if either kid could have been a son.

In Monty Hall, the info that you don't intuitively consider is that Monty is providing additional information. You think of it as 50/50 because Monty ruled out a goat and car has to be behind one of two remaining doors, but actually the way it works is you chose a door that 1/3rd had a car, leaving 2/3rds chance of car on the other two doors. Then Monty eliminated one of those two doors, still leaving 2/3rds chance of car on the remaining door. So you should switch to that door. In Monty Hall, first you divide the set into a 1/3rd chance group of 1 door and a 2/3rd chance group of 2 doors, then Monty makes the second group a 2/3rd chance group of just 1 door.

</comment></comment><comment><USER54> Spoiler: Tuesday was the name of his horse.

</comment><comment><USER55> ANYONE WHO SAYS THE ANSWER IS OTHER THAN 1/2:

Let's simplify the question:

If a man says "I have two children, one was born on a Tuesday," what is the probability that they are both born on a Tuesday?

Is the answer to this 0 or 1/7 in your opinion? (Or something different).

<comment><USER25> You can follow a similar process to work out the probability as for the original question. For any two children, the possibilities are:

Child 1 born Mon, Tue, Wed, Thu, Fri, Sat, Sun

Child 2 born Mon, Tue, Wed, Thu, Fri, Sat, Sun

We know that one of the children was born on a Tuesday, but we haven't said whether it's Child 1 or Child 2 (and that lack of information is key to understanding the original problem), so our unknown child could also be either Child 1 or Child 2.

With that in mind, 'unknown child' has 14 possible options except that we know one of those options (our known Tuesday child) is already taken - we don't know whether it's Child 1 or Child 2 but that doesn't matter, we just know that one of them is already taken. That leaves 13 possibilities for unknown child, only one of which is 'born on Tuesday' (since we've removed the other 'born on Tuesday' option), so I would say the answer is 1/13.

<comment><USER55> This is ridiculous. Let's do some queries on the world:

From all women: (some 3 billion)

the ones who have exactly two living children: x matches

the ones in which it is true for them to say "One of my children was born on Tuesday.". (this is true or false for every mother that comprises x. y mothers remain (can answer "true" for that question")

the ones that can say "both my children were born on Tuesday": z matches

are you telling me that sizeof z is 1/14th the sizeof y???

(because for me it is either 1/7 that size or exactly 0 if the correct meaning of "one of" is "exactly one of and not both of")

<comment><USER55> Wait, I think I get it. (Sorry, too late to update).

This is indeed ingenious. The key is the step from x to y. The women in x who can say "one of my children was born on Tuesday" are the ones who can say "EITHER my first OR my second child was born on Tuesday"; the initial constraint (when you meet the person) is thus: "women who can say I have exactly 2 children and it is true to say EITHER my first OR my second child was born on a Tuesday"; obviously this is far more than 1/7th. Then the additional constraint "BOTH of them were" is a smaller addition than 1/7th.

It's not 1/7th the first time and 1/7th the second time, because the question wasn't "of women who can say they have exactly two children, the number who can say 'my elder child was born on a Tuesday'" and then "of these the women who can say 'my younger child was also born on Tuesday". This would indeed be 1/7th each time.

instead y is "EITHER my elder OR my younger child was born on Tuesday". This obviously results in a set that is greater than 1/7th of all women with two children, and, consequently, it is no surprise that there is a correspondingly smaller than 1/7th possibility that both were.

<comment><USER25> Bingo :-) I was just racking my brain for a different way to explain it but luckily you got there first!

It's a real mind-bender.</comment></comment></comment></comment></comment>


The Structure of a Real Apology - <AUTHOR> http://spin.atomicobject.com/2013/07/24/real-apology/ <comment><USER2> This is absolutely awful, or doesn't apply. Especially in the context of communicating with a cynical userbase, but in many other contexts as well.

It does not mention the ONE thing that makes an apology worth anything.

The ONE thing you have to include is evidence of a positive action you have taken that will actually prevent this from happening again. Not some kind of 'promise.'

For example, here is an Obama non-apology for the NSA spying on Americans (illustrative example, not a quote): "I am dismayed, as all of you are, at what I've recently learned of data collection of innocent Americans by a government agency. It was done under my watch, and I take responsibility. I promise you, the people who overstepped their boundaries will be removed from their positions and punished. Anyone who's suffered personally as a result of these violations will have freedom of information act possibilities to learn how their information was misused. They can petition the courts for redress, in line with our Constitution. Finally, I want you to know that I have let you all down. I can only ask for your forgiveness."

That pretty much follows steps 1-5. It's also absolutely useless.

here is a good apology: it can repeat any of the language above, for fluff. The main point is this "this morning I signed an executive order ordering the sealing, for 150 years, of all innocent American's personal information that has been collected. The sealing is to be done by means of military-grade encryption. The keys will be held in the supreme court of the United States, by its chief justice John G. Roberts, Jr. Every morning between he will come in half an hour early and sign off on warrants requesting any decryption, only upon probable cause, supported by Oath or affirmation, and particularly describing the records to be decrypted, and the persons or things to be seized."

That's "funny", but it's 10000000x better than the apology above. The only way to apologize is to list a step you've actually taken to actually prevent it happening again.

Fuck promises.

<comment><USER3> _" The only way to apologize is to list a step you've actually taken to actually prevent it happening again."_

Sometimes you need to issue an apology before you have time to take any concrete action. In fact, in crisis management, time till expected response is often more critical than noodling on precisely what must be done. You're in a triage situation, and the first thing you need to do is stop the bleeding.

This is why "promises" get made, because they're the first step in figuring out a genuine series of restitutive actions. Often the first thing people want to hear -- and need to hear -- is a simple acceptance of responsibility. The acceptance should be followed by a legitimate demonstration of understanding: of the damages caused, of the seriousness of the issue, etc. This is followed by a pledge to investigate, or to take serious actions.

Now here's the important part (to your point): 9 out of 10 apologies just leave it at that. There's no follow-through or followup. This is why people have been desensitized to the standard-issue apology as detailed in this article. They're used to seeing boilerplate and empty promises, but the devil is in the details. Listing a concrete action taken is a great way to go, but sometimes you don't have time to take such action (or fully consider the ramifications) before the apology needs to be issued.

In summary: 1) take serious stock of the issue ASAP, 2) state sincere apology demonstrating accountability for the fuckup and responsibility for the fix, 3) maintain communication as fixes are implemented, and detail them.

</comment></comment><comment><USER4> Excellent points - something every tech startup founder should keep in mind.

Teh Portly Dyke's "How to Fuck Up" is a good companion piece. [http://portlytruestories.blogspot.com/2007/11/how-to-fuck- up...](http://portlytruestories.blogspot.com/2007/11/how-to-fuck-up.html)

</comment><comment><USER5> I'm not sure I understand who this is intended for. (Then again, most apology advice I've read about is like that.) It seems like it's aimed at people who act in bad faith, but then, they're the last people we need to teach how to make a genuine-seeming apology!

Case in point: "Don't Make the Apology about You ... 'I was trying to…'"

What? I would certainly want to know what led to the wrongdoing so I know whether it's a systematic problem. That doesn't make it "about the apologizer"; it's conveying useful information.

My guess is that the writer has in mind lots of people who _are_ narcissistic and so generalized that lesson to good-faith attempts to help the recipient understand what happened.

The article can be summed up as "throw yourself at the feet of your customer while conveying nothing but easily-faked feelings".

<comment><USER6> It might be aimed at people who might buy into fake apologies. Generally, the people who take the apology at face value aren't the ones being apologised to, and it can get pretty ugly. Also, it seems like a good way of removing plausible deniability from people who make those kind of apologies.

</comment></comment><comment><USER7> I don't think you can really -write- an apology. It's the human emotion that's at the heart of a real, genuine apology.

Anyone can say "sorry", when it's in an email, and the author could really be cut-up about it. It's far too easy to pay lip service by using a prepared note following the 5 steps (especially an email apology about having an intrusion in your databases) but it's harder to look people in the eyes and keep up the act.

</comment><comment><USER8> The most effective apology is often not as complicated as this. The crucial part is asking for forgiveness.

"I apologize for ______. Please forgive me."

I learned this a long time ago from a CareerTrack seminar on communication and it has served me well in getting out of many a bind - allowing me to move forward and past mistakes, some very big. It is especially effective in written communication like emails to collaborators.

<comment><USER9> From what I remember about Crucial Conversations, the kind of apology you're suggesting works best in certain circumstances (usually one-time offenses). That type of apology loses meaning, though, when your behavior is the problem rather than a specific action. For example, if you're late to work for the 10th time in a row, apologizing and asking for forgiveness is probably going to be more irritating than helpful. The intention to change is what becomes more important.

<comment><USER8> Very good point. This is definitely not for repeat offenses.

Without going into details, at a job once, once I was _threatened_ to be put on a PIP [1], I dramatically changed my behavior. At that point, as you mentioned, you are way past apologies and into the realm of 'oh sh_t, I may get fired" and very, very unambiguous communication (from your boss). Only someone is really, really stupid would ask for forgiveness at the point - because the tone is very measured and corporate and grim reaper serious.

[1] [http://www.tlnt.com/2012/06/01/weekly-wrap-the-dirty- little-...](http://www.tlnt.com/2012/06/01/weekly-wrap-the-dirty-little- secret-of-performance-improvement-plans/)

</comment></comment></comment><comment><USER10> People seem to get away with non-apologies all the time (of the "I'm sorry you're such an oversensitive asshole that you were offended by what I said" variety) , so I'm not sure true contrition is necessary. In fact, it probably makes you look weak in this day and age.</comment>


Could the Scottish Parliament Stop the UK from Leaving the EU? - <AUTHOR> http://www.bbc.co.uk/news/uk-scotland-36635012 <comment><USER2> Tl;dr, no. Westminister has sovereignty ultimately.</comment>


Paternoster Lifts: Cyclic Chain Elevators with No Buttons, Doors or Stops (2016) - <AUTHOR> https://99percentinvisible.org/article/paternoster-lifts-cyclic-chain-elevators-no-buttons-doors-stops/ <comment><USER2> I work in a building with one. It takes 15.5 seconds between floors, wich is a bit slower than our elevators, but because there is no door, buttons and usually no queue it really is very quick.

In the course of the day it makes moving between adjacent floors for meetings completely effortless.

<comment><USER3> Unless you are disabled, moving between adjacent floors is pretty easy with stairs. And lots of types of disabilities that would prevent the use of stairs would seem to make these risky or impossible to ride. All in all, I'm pretty happy these never caught on.

<comment><USER2> Add 15.5s per floor, no perspiration, bring a cup of coffee.

Sure, if you love stairs by all means take them. But no, it's just not convenient on the same level.

</comment></comment></comment><comment><USER4> Previous discussions on the Paternoster:

[https://news.ycombinator.com/item?id=9284672](https://news.ycombinator.com/item?id=9284672)

[https://news.ycombinator.com/item?id=10058885](https://news.ycombinator.com/item?id=10058885)

</comment><comment><USER5> Three of these were scheduled to be replaced several years ago at my university - the administration however pulled the "voluntarily call the historical conservationists" trick and they are still operational.

</comment><comment><USER6> We had a pair of Paternoster in my place of work (in addition to two pairs of elevators) until a year ago. They've since been replaced by a small pair of elevators, which work fine, but the paternoster just had more character. Power usage was given as the reason for replacing them.

<comment><USER7> That and they're super unfriendly to anyone with a movement disability.

<comment><USER8> Is that relevant though if you have lifts too?

</comment></comment></comment><comment><USER9> How easily these can be used by people with disabilities? Someone in a wheelchair or on crutches who can't move fast enough would be frustrated or, at worst, seriously injured by one of these.

<comment><USER10> Why is that relevant? Of course they cannot safely be used by such people - they'll just have to use something else - like stairs or regular elevators.

<comment><USER11> Why is that not relevant? Accommodation for disabilities is an important purpose of most elevators, and it's a reasonable question to ask.

</comment></comment></comment><comment><USER12> There are 3 places left in Germany where they're allowed to operate. One of those places is Leica in Wetzlar. It's absolutely fun to ride it, much faster than conventional lifts, but it's understandable that they're being shut down for safety reasons.

<comment><USER13> Really, only 3? Because there's two alone in Kiel (old city hall and the Landtag)

<comment><USER12> Then this information might be wrong, I only heard it from some employees.

<comment><USER14> Yeah, it's a factoid that you usually hear from people surrounding places that have one installed, but given that I've seen more than 3 in person, it's certainly not true.

There is a list in the German Wikipedia[0].

[0]: [https://de.wikipedia.org/wiki/Liste_von_Paternosteraufzügen](https://de.wikipedia.org/wiki/Liste_von_Paternosteraufzügen)

<comment><USER15> That's quite a few! A lot of those show up on the list as "nur für Mitarbeiter" and "nicht öffentlich"; is there a nice list anywhere of those few that are open to the public? I'd like to try one sometime while they're still operating.

<comment><USER14> Due to the no-doors nature of a Paternoster the "employee only" is usually weakly "enforced" by a sign inside the Paternoster that says so, in order to waive liability. So if you are willing to go slight grey-hat, a lot of the ones listed as "employee only" are still accessible for you.

</comment></comment></comment></comment></comment></comment><comment><USER16> I had the "pleasure" of using one in Germany. I had the worst sense of dread when I was getting into and out of them. But I think I just needed to get used to them I guess.

<comment><USER17> If you think about it, it is orders of magnitude less dreadful than walking on a street with hundreds of cars around you, driven by strangers.

<comment><USER18> Cars are periodically made to stop to let you through. This is more like trying to cross a freeway.

<comment><USER19> I think you mean "cars are periodically _requested_ to stop", at least, I haven't seen any crosswalks around here with physical barriers that _make_ the cars stop.

But unfortunately, that's not the only hazard pedestrians face from cars, not too long ago I saw a car jump the curb and run into a (fortunately) empty bus shelter. If anyone was waiting at that shelter, they'd have ended up under the car.

So yeah, I'd feel safer taking a paternoster every day than walking to work... at least then, my safety is in my own hands.

<comment><USER8> > I think you mean "cars are periodically _requested_ to stop"

What a pointless and nonsense distinction to make. I was made to eat my vegetables as a child. They weren't physically forced down my throat.

</comment></comment></comment></comment></comment><comment><USER20> I did a work experience placement at a UK hospital about twenty five years ago, and they had an operational paternoster lift. It took about two days of regularly riding the thing before I plucked up the courage to ride it all the way over the top.

<comment><USER21> Oh my I hadn't even thought about what happens at the top or bottom. Was it completely enclosed? Do you end up going behind the lifts that are facing the opening or is there a divider?

What if the power shuts off at the peak? Or worse, at the bottom in the less trafficked basement level? So many questions.

<comment><USER22> For questions of this type, YouTube can be good. Here is a random video I found by typing "paternoster over the top" (it's one of the suggestions once you type "paternoster") into the search box: [https://www.youtube.com/watch?v=KoCQ6tq5wJE](https://www.youtube.com/watch?v=KoCQ6tq5wJE)

</comment></comment></comment><comment><USER23> It's not a paternoster, but I actually wonder how common is this in the world - almost every lift in every apartment block in Poland I've ever visited only had outside doors but no door inside(so you could see the floors moving past and yes, had to be very careful not to lean on that side). Have other, non ex- soviet countries ever used such design?

They look like this from the inside:

[https://youtu.be/I4hg_jGzO3U](https://youtu.be/I4hg_jGzO3U)

<comment><USER24> I live in the most soviet country of them all, and I have never seen this lift design even in the dingiest khrushchyovkas. Seems incredibly unsafe!

<comment><USER25> There is one in the building where I used to work in Norway. But it has been fitted with a light curtain so that it won't move if there is anything close to the door. It's perfectly safe now.

</comment></comment></comment><comment><USER26> This what not what I expected - I spent a summer as a student working in a space with a manual cargo lift with no buttons, instead there was a hole in the wall with a chain. To go up you pull down on the chain, when you reached your floor you grab the (stationary, but the lift is moving) chain, which pulls it up and it stops, pull it up a bit further and it goes down - you have to guess the stop height to pull the chaiun at just the right spot

</comment><comment><USER27> The MULTI seems potentially awesome; even when used as a pure vertical lift, it looks like it could be used to make something that had multiple cars with passing, allowing a safe stops-and-doors system with the density of a paternoster but reduced opportunity for and severity of traffic jams, which is kind of the best of all worlds.

</comment><comment><USER28> The Danish parliament building, Christiansborg in Copenhagen, built just around one hundred years ago, has such a contraption for MPs and their entourage flitting between floors. The article's main photo could almost be it, and possibly is, though something about wood and marble looks slightly off.

</comment><comment><USER29> I watched 'Metropolis'(1927) the other day[1]; The rich main character lived in a building with these; I was not aware it was an actual thing, rather than just "The most future looking elevator that the effects team could cobble together" \- The movie really did have some other amazing effects, so it was reasonable, I guess, to assume that this, too was a trick.

[1]I joked that it was more a dark warning of the dangers of bad civil engineering than the social commentary it's generally thought to be.

</comment><comment><USER30> Since it's non-stop, wouldn't this take more power than modern elevators? Why to keep running large number of them despite other concerns including safety? One or two kept in a heritage museum is understandable, but this large number is a bit hard to digest.

<comment><USER31> > _Why to keep running large number of them despite other concerns including > safety?_

Because people apparently like them and because replacing an elevator is an expensive affair.

It's not clear that paternoster lifts are really more dangerous than standard elevators. The failures of safeties described can happen with standard elevators as well.

<comment><USER32> Yes but there are also accessibility concerns. These are public spaces, and at least in the US there are laws about public accessibility. How would someone on crutches, or in a wheelchair, or with a service dog, use such a thing? I assume that they aren't the only option available in the building.

<comment><USER33> They would use a separate elevator hidden a bit off to the side, and they wouldn't have to wait for it because most other people would be using the paternoster.

A paternoster can transport at least 12 people per minute (depending on the speed of course) per direction from any floor to any floor, more if their travel paths don't overlap or people ignore the "max two people per cab" sign.

</comment></comment></comment></comment><comment><USER34> Interesting, If it could be made inherently safe somehow this would be so much more efficient, but I just can't help the persistent image of Resident Evil "the lift scene" from entering my head.

<comment><USER33> I'm not sure how inherently unsafe they are compared with regular elevators that have shaft doors but not cabin doors.

They can theoretically squish you between the floor of a rising cabin and the ceiling, and between the ceiling of a cabin going down and the floor. To prevent this, you could place a movable board coupled to a sensor at ceiling of the cabin and the ceilings of the entry "doors". If the cabin starts squishing someone while going down, the board gets pushed upwards, and triggers an e-stop. If it starts squishing someone going upwards, again, the outer board at that floor gets pushed, and again, triggers the e-stop. (The board would have to be able to move more than the elevator needs to stop, obviously).

At that point, the remaining risk seems to be similar to regular elevators that don't have inner doors.

(Existing installations seem to have solved this passively with breakaway panels and gaps, which is probably good enough, but would make it possible to jump from the cabin into the shaft while it is between floors.)

</comment></comment><comment><USER35> The article mentions that it's a problem to ride the elevator past the top or bottom floor, but it is unclear why. I don't see why this should be an issue.

<comment><USER36> The one I know has several signs on the exposed inside walls above the topmost floor all assuring you that you will not be turned upside down, or folded, or run through a meat grinder.

Based on the adage that every (non-)warning sign is there for a reason, I can only assume that there have been incidents of people panicking after they realized they had gone to far.

Just to be clear: it's absolutely safe to go around. Any other stories you may hear are the inside joke of those five beaurocrats on the top floor enjoying their tiny fiefdom of chaos.

Edit: could people downvoting this please give a reason? I'm really not complaining, just terribly curious what could possibly stroke people the wrong way in this benign post. Or is this the Paternoster conspiracy coordinating to keep their secret?

<comment><USER37> _Just to be clear: it's absolutely safe to go around._

There is a variation which isn't - the "man lift".[1] Those are dangerous, and sometimes seen in parking garages for staff only. Those really do turn upside down at the top. They're usually equipped with a switch to shut them down if someone rides past the top landing.

[1] [https://www.youtube.com/watch?v=7KzEAs3Yclg](https://www.youtube.com/watch?v=7KzEAs3Yclg)

</comment></comment></comment><comment><USER38> I saw one of these at a bicycle shop in Bern circa 2006; was too scared to try so took the stairs.

</comment><comment><USER39> There's paternosters in Babylon Berlin, an awesome show BTW

</comment><comment><USER40> Sounds similar in operation to a Shabbat Elevator ([https://en.wikipedia.org/wiki/Shabbat_elevator](https://en.wikipedia.org/wiki/Shabbat_elevator)) which visit every floor automatically, but still have traditional doors and don't run on a looped circuit.

The debate over whether such devices violate religious rules is pretty interesting. I have to imagine if there's an omnipotent deity looking upon on his followers from on high, he'd be thinking something like: Very clever, humans, but you know exactly why I made the rule, and it wasn't so you could win on a slight technicality by not pushing any buttons.

<comment> the-dude I was under the impression Jewish people are actually enjoying bending the rules through such clever hacks.

There are also Shabbat ovens. Turn on/off automatically, so you are not operating the machine!

<comment><USER41> Not to mention Shabbat lamps, which have an opaque shade you can put over them so you won't notice the light while it technically stays on. I also think any reasonable deity would be pretty miffed at this avoidance of the rules, but then again I suppose the Jews would know their god better than me.

(In a somewhat more reasonable/funny bending of the rules; Jews are apparently also forbidden to "tear cloth" on the Shabbat, since that counted as work back in the day for tailors etc. However, after some discussions in the rabbinate there is now "Shabbat toilet paper", which does not come on a roll but as loose leaves of paper so you don't have to do any tearing on the day itself.)

<comment><USER11> My understanding (as a secular Jew, so I could be wrong) is that the attitude is that if God hadn't meant for there to be loopholes like this, He wouldn't have written the rules this way in the first place. In a way, trying to obey the spirit rather than the letter of the law is implying imperfection on the part of the author of the laws.

<comment><USER41> That actually makes a lot of sense, (provided you believe He exists and is infallible in the first place)

After more reading, there is apparently a sect that (while otherwise quite orthodox) considers electricity from photovoltaic power not to violate the commandment of "not making fire" and so provided they have PV panels or batteries they can use electricity freely on Shabbat. Still not for working of course, but a light would be OK.

</comment></comment></comment></comment></comment><comment><USER42> glad these are on their way out other than some eccentric toy</comment>


YouTube - Intel Acquiring McAfee - <AUTHOR> http://www.youtube.com/watch?v=7SWl8PMKtNY <comment><USER2> Publicly announced they are sleeping together.

</comment><comment><USER3> Shouldn't they be going after AV that works?

</comment><comment><AUTHOR> For $7.69b.</comment>


Amazon - The Walmart of the web - <AUTHOR> http://www.economist.com/node/21530980

<comment><AUTHOR> The internet giant's new tablet computer fits its strategy of developing big businesses by charging small prices. The report compared the prices of 100 randomly selected goods at each of 24 American retailers with those items that were also available on Amazon.com.

To me, it's shocking to see that Amazon's prices are lower than even Walmart. Only 2 companies fared better - Costco and Dollar General. I think Kindle Fire's business model is going to create some headaches for iPad.</comment>


When is it OK to use goto? - <AUTHOR> https://studio.youtube.com/video/2EDKzknxPQc/edit <comment><USER2> In languages that support goto, but do not have try catch syntax. The appropriate use of goto for failure states to properly handle deallocation of allocated memory. If condition not met goto: cleanup

</comment><comment><USER3> Link is broken.</comment>


Parasite theory stirs a revolution - <AUTHOR> http://www.boston.com/news/science/articles/2007/12/31/his_parasite_theory_stirs_a_revolution/

<comment><AUTHOR> See also: How to cure your asthma or hayfever using hookworm - a practical guide [<http://www.kuro5hin.org/story/2006/4/30/91945/8971>]

</comment><comment><USER2> I just envision selling "healthy dirt" in the drugstores ;-) Rub yourself into "safe dirt" in the morning and in the evening to avoid allergies...</comment>


Treasure Map: Rare Coin Dealer Sues Google over Directions to Home - <AUTHOR> http://blogs.findlaw.com/legally_weird/2010/02/treasure-map-rare-coin-dealer-sues-google-over-directions-to-home.html

<comment><USER2> I guess Google is a larger target than the Palm Beach County Property Appraiser ( <http://www.co.palm-beach.fl.us/papa/index.htm> ), or else he doesn't know it exists and gives _way_ more information than Google does about his home.

<comment><USER3> He's probably more interested in their yearly profit.

</comment></comment><comment><USER4> I'd guess this is what he's objecting to: [http://maps.google.com/places/us/florida/stuart/sw-3rd- st/30...](http://maps.google.com/places/us/florida/stuart/sw-3rd-st/300/-jon- harris-rare-coins?hl=en)

First of all, Google didn't create this information, they just scraped it. The first "More about this place" link has the same address. So if anything, he should be be suing that site.

But really, it's his fault, because something publicly available suggested that his home address was the address for his rare coin shop.

More importantly, there's a link at the top that says "Business owner?" that allows him to suspend or edit listing.

He's not going to get very far in court. Luckily for him, it won't cost much because it said in the report linked to in the article said he's representing himself.

</comment><comment><USER5> How about this? Don't do business out of your house. Move the precious coins to a safe place instead.

Rule 1 about being pissed off that someone told someone else something about you that you didn't want disclosed: do NOT make a big deal out of it. It just draws more unwanted attention.

<comment><USER6> Too true, but... Rule #1 for wanting to profit off of something that's actually innocuous: Make a big deal about how the innocuous thing is actually dangerous to you and your family and then sue the richest person you can find.

</comment></comment><comment><USER7> _shrug_

Anyone can file a lawsuit.</comment>


True Entrepreneurs - <AUTHOR> http://redeye.firstround.com/2009/05/true-entrepreneurs.html <comment><USER2> "I've often believed that the true measure of an entrepreneur's character comes not during the boom times, but how they react in times of adversity and challenge."

Couldn't be more true! I have a friend who runs his own restaurant. He's successful because of his character and how he responded to diversity. When he was starting out, I remember he would have rather spent his money to get a better stove for the restaurant than a new couch for his living room.

There's definitely a cost to that sort of attitude, but that sort of tenacity makes for a business that just won't die.</comment>