Mathematics - 2012-01-26 (page 1 of 6)

12:00 AM

I should probably be drinking right now. Hang on.

@yoda All I'm saying is that if you do not have the expertise of a mathematician, then you shouldn't go around and say things like "skins thinner than a soap bubble."

Jonas Teuwen

I should probably be sleeping right now.

Asaf Karagila

@JonasTeuwen I should too. But drinking is more fun.

I brought a nice glass of arak.

Jonas Teuwen

I have already done that.

Mariano Suárez-Alvarez

internet skin thickness is orthogonal to math expertise...

2

Asaf Karagila

12:01 AM

Cheers!

Jonas Teuwen

Cheers!

Skullpatrol

Cheers!

J. M.

Hi @Mariano!

Mariano Suárez-Alvarez

hello :D

anon

A couple of months and I'll get to join the chatroom drinking parties ;)

Brian M. Scott

12:02 AM

@MarianoSuárezAlvarez And MSE is probably the politest site this Usenet veteran has ever seen.

Jonas Teuwen

So, what kind of space are these "internet skin thickness" and "math expertise" in. And what inner product?

Asaf Karagila

Cheers!

Jonas Teuwen

(I don't understand the remark)

Mariano Suárez-Alvarez

@BrianMScott, heh

indeed

J. M.

@anon ...I thought you were drinking age already? Or is your state a killjoy? ;)

Brian M. Scott

12:03 AM

Which one, Jonas? Mariano’s?

Mariano Suárez-Alvarez

FreeNode's #math is fun :)

and no one complains when I ban people there :D

Jonas Teuwen

@BrianMScott Yes.

Skullpatrol

@JonasTeuwen They are in the space known as the "ethernet"

Brian M. Scott

He’s saying that the two things are completely unrelated. No correlation.

Jonas Teuwen

Ahh!

anon

12:04 AM

Drinking age is 21 nationally isn't it...

(in the US)

Jonas Teuwen

So he's using analytic language in a probabilistic context.

J. M.

@anon Oh, I was under the impression they already lowered it. Pfft...

Fortuon Paendrag

I would think they would be inversely related, if anything! The higher one climbs, the more touchy one becomes, no?

Skullpatrol

@JonasTeuwen The same "ether" that Einstein EVAPORATED with relativity.

J. M.

Ivory castles are brittle, you see. :)

Jonas Teuwen

12:06 AM

I still think it is strange that the minimum drinking age is above the age where one can get a drivers license 8-).

Asaf Karagila

Americans are known to be a bunch of weirdos anyway.

2

I mean, Fahrenheit? Seriously? Not to mention feet, mile, &c.

Brian M. Scott

@anon With some state and local family member or location exceptions to underage consumption or possession laws.

badp

@MarianoSuárezAlvarez I tihnk it's mainly because there are many more bans, so people accept them as part of life.

I think we should make our own lives easier, stop worrying and start loving the banhammer!!

Jonas Teuwen

I'm off to bed. Bye!

Asaf Karagila

Wuss.

Brian M. Scott

12:10 AM

G’night!

Asaf Karagila

Stay up and drink more.

J. M.

Also it is ridiculously easy to kick out somebody from IRC... :)

Skullpatrol

@AsafKaragila feet, mile, &c came from the British

J. M.

@AsafKaragila Apparently he already did. ;)

Jonas Teuwen

@robjohn So would Intaglio also be very suitable to draw say a decomposition of an open set in squares? I'm using TikZ now. (LaTeX support is necessary, and I'm using pdflatex so no ps-tricks for me!)

Asaf Karagila

12:11 AM

@JM Oh... if only this was so in here.

@JM This is why I said more :-)

J. M.

@AsafKaragila Any more and he'd be embalmed alive...

Asaf Karagila

@JM I don't see the wrong in that...

J. M.

*facepalm*

Asaf Karagila

You might want to suggest that to J. Dahmer by the way.

Jonas Teuwen

@AsafKaragila You seem to be fascinated by cannibals...

J. M.

12:13 AM

I'm not quite sure that guy you speak of is fond of pickles...

Asaf Karagila

@JM Sure he was.

@JonasTeuwen Actually all form of mass-serial killers are fascinating. I mean what gets a man to kill dozens of people and do stuff like that to the bodies?

Jonas Teuwen

A lack of antipsychotics?

Asaf Karagila

Possibly.

Jonas Teuwen

With enough Haldol they wouldn't do that 8-).

J. M.

On the other hand, too much of 'em and all the concentrated wrath becomes self-directed instead of people-directed...

@JonasTeuwen You are becoming too familiar with Dr. Paul's products... :o

Jonas Teuwen

12:18 AM

:O. He was in the TV show about electing the "Greatest Belgian of All Time".

Asaf Karagila

@JonasTeuwen Was the criterion "How long before crumbling at the hand of the Nazis"?

Jonas Teuwen

(when he was dead already)

J. M.

Ah, good thing. Too bad the guy died before getting a Nobel.

Jonas Teuwen

That might have helped.

J. M.

Actually, even if he hadn't come up with Haldol/Risperdal, people would still be thankful to him for Imodium...

I'd say it's his most famous product.

Asaf Karagila

12:21 AM

So all those crazy folks being all numb and well rested is just a biproduct?

J. M.

@AsafKaragila It's not much of an exaggeration, actually. Which is a bit scary.

Asaf Karagila

What is not an exaggeration?

J. M.

@AsafKaragila the restedness being a mere byproduct

anon

"biproduct"? That certainly sounds like a typo a mathematician would make.

4

Asaf Karagila

I knew it didn't seem correct :-)

@JM Of the Haldol?

J. M.

12:25 AM

@AsafKaragila Yeah. It wasn't exactly designed at a time where all the neurotransmitters were well-known, so it's still a bit of a shotgun, albeit with a tiny scope attached to it.

Asaf Karagila

@JM Hah, interesting.

Jonas Teuwen

It is still the most potent antipsychotic know right?

It can make you stare at the wall for some days without thinking much.

Asaf Karagila

@anon Remember we talked about scary clowns?

J. M.

@JonasTeuwen Well, Dr. Paul's other product seems to be rivaling it, from the studies...

anon

@Jonas: I already do that, though.

Jonas Teuwen

12:28 AM

I know a dude that can even be manic after a shot of Haldol 8-).

anon

Scary clowns? I do not recall such a conversation...

Asaf Karagila

About King's It and whatnots.

Oh, it was yunone. Nevermind @anon :-)

J. M.

A common problem. They're almost homophonic...

Brian M. Scott

Unless yunone is three syllables.

J. M.

@Brian: if you don't mind a personal question, I read from the transcript that most of your papers were pre-TeX?

(assuming I read the transcript correctly)

Brian M. Scott

12:36 AM

That’s right; I started using it when I started posting here.

Asaf Karagila

@JM I first read that "They're almost homotopic"

J. M.

@BrianMScott Wow. So you really did heavily use a secretary?

Brian M. Scott

I did indeed. We had a very good one.

J. M.

The Selectric was already in use at the time, right?

Brian M. Scott

I didn’t impose on her for exams, though; I wrote those up longhand and ran them off on the ditto machine.

Yes; that’s what Joyce used, in fact.

It’s even older: I used an IBM Executive, which was a similar machine, when I was in the army in 1970-1.

Jonas Teuwen

12:39 AM

Good night!

J. M.

Good night, Jonas.

Brian M. Scott

G’night, Jonas!

J. M.

@BrianMScott Yeesh, that is quite a long time ago...

(I like asking these questions; it helps me temper my "old days" nostalgia...)

Brian M. Scott

Doesn’t feel all that long, sometimes.

Some more recent memories are a good deal dimmer.

J. M.

Did you have papers that you now wish you had (La)TeX at the time you were writing them?

Brian M. Scott

12:43 AM

I can’t think of any. Adding special symbols by hand was never a big problem.

robjohn

It appears that I missed yoda again :-(

@JM: at least you're still here :-)

Asaf Karagila

@robjohn Fear not, young padawan. Learn will soon dark side force of the you.

robjohn

@AsafKaragila :-)

Asaf Karagila

Mmmmm...

Brian M. Scott

Is that a liquid Mmmmm?

robjohn

12:45 AM

@AsafKaragila Did something happen here? yoda has come and gone and I see two other mods here.

Asaf Karagila

@robjohn Oh... "someone" had flagged my quotes from the Maddox rant on mathematics.

robjohn

@AsafKaragila Ah, people being too itchy on the trigger finger.

Asaf Karagila

@robjohn Nah, "someone" that dislikes me greatly and took the opportunity to flag a message by me.

robjohn

too much politics :-(

Asaf Karagila

Well, I don't really care.

robjohn

12:53 AM

All of the time wasted by bringing in the mods needlessly is not good.

Perhaps that is not a lot of time, but still.

Hi @Bill. Don't try to speak :-)

Asaf Karagila

Bill, if you cannot use the chat right now, I think I have a suggestion how to bypass this restriction: you can change your "main SE user" to a different SE site for the time being, and from that site you should have enough reputation for chat.

J. M.

He does have another account with a nontrivial amount of reputation...

...on a different SE site.

Asaf Karagila

Which is why I suggested this in the first place.

anon

How does one change their "main SE user"?

Asaf Karagila

Go to your chat profile and click "change" by the parent user.

Srivatsan

1:08 AM

@robjohn Hey, what's up with this 4 minutes later..., 38 seconds later... and 28 seconds later that I see in chat?

robjohn

@Srivatsan for what? I usually see something like 2 hours later... when there has been a long break.

Asaf Karagila

31.4159 seconds later...

Srivatsan

@robjohn One second. Let me take a screenshot.

Asaf Karagila

@Srivatsan 1 seconds later...?

J. M.

"seconds"? Wow, that's granularity...

Srivatsan

1:10 AM

Weird! I refreshed the screen and they went away. It's all back to normal.

robjohn

@Srivatsan How long since you've slept? :-)

Asaf Karagila

Either way, it's 3:10am and I have to sleep for like 5 hours now.

Srivatsan

@robjohn I insist that I know what I am talking about =)

J. M.

Dear Next Person Who Opens a Pluralization 'Bug', I will personally come to your house and bludgeon you to death with a giant S

Tweeted by codinghorror on February 1, 2009 at 2:33 AM

robjohn

That is Jeff Atwood's avatar...

J. M.

1:12 AM

Yes, that's Jeff's twitter account.

Asaf Karagila

Why did you reply that to me?

J. M.

You were talking about "1 seconds later"... :)

There were people who were complaining about it in meta.SO when I checked.

Asaf Karagila

I was merely making fun of Ganesh. Err... Srivatsan ;-)

Srivatsan

Now, who is Ganesh?

J. M.

You're a nasty piece of work, Asaf... :P

Brian M. Scott

1:14 AM

A Hindu deity with an elephantine nose.

Srivatsan

(Ah, that guy.)

Asaf Karagila

"Ganesha is considered to be the Lord of letters and learning." (from Wikipedia)

Not that I knew that before right now, but still... that's a compliment more than a slur :-P

Srivatsan

Thanks. =)

Asaf Karagila

@Srivatsan I have to ask, once and for all, what sort of belief system were you brought up upon/have right now?

J. M.

If you ask me, there are only a few things more badass than making an entrance riding on an elephant...

...with full tusks.

Asaf Karagila

1:17 AM

@JM Making an entrance whilst riding Your Mother? :-P (Literally, not as a euphemism)

Srivatsan

@JM He doesn't ride an elephant. (He rides a mouse, if that's relevant.) His face looks like an elephant's.

J. M.

@Srivatsan I know; I was just thinking since you guys brought up elephants anyway... :)

Srivatsan

Here's a picture of the said G..

@JM Ah, ok.

J. M.

@AsafKaragila It's a bit hard to ride a tomb, no?

Brian M. Scott

For the fussy, गणेश; for the slightly less fussy, Gaṇeśa. See also the webcomic Digger.

J. M.

1:19 AM

Ooh, script...

Asaf Karagila

@JM Not if it has wheels...

J. M.

@AsafKaragila I couldn't afford wheels, dope. :P

Asaf Karagila

Dope or not. I am going to bed.

Srivatsan

@AsafKaragila Ah, "what sort of belief system?" -- I am a Hindu; so I believe - in a loose sense - all these gods, incl. the one we are discussing. [Of course, Ganesh is not a belief system, but as a deity as correctly pointed out.]

J. M.

@AsafKaragila Good night.

Asaf Karagila

1:20 AM

Farewell cruel chat! I'll be back in a few hours!

J. M.

And I have to get groceries. See you guys later.

robjohn

@AsafKaragila sleep quietly

Brian M. Scott

@JM Your tongue’s lopsided! :Þ

Srivatsan

In fact, I don't have a very good answer to what "belief system" I was brought up in.

Asaf Karagila

@Srivatsan [I know that Ganesh is a deity]

Brian M. Scott

1:21 AM

G’night, Asaf.

Srivatsan

@AsafKaragila Yes, I am aware of it; that's why the "of course". =)

@BrianMScott Ooh, I am impressed. How do you do this? And how do you know this (if you did know)?

Brian M. Scott

Cut and paste from Wikipedia, in this case. I don’t think that I have a Devanāgari font, but I could have done the other part the hard way.

robjohn

2:02 AM

@Srivatsan: $n=1:\frac12,n=2:\frac1\pi,n=3:\frac18,n=4:\frac{4}{3\pi}$

Srivatsan

@robjohn Is this a teaser? :)

robjohn

@Srivatsan yes :-)

Srivatsan

Ok, let me post the question now.

@robjohn Do you happen to have a link to that original question?

anon

I think we should take bets on when Arturo hits 100k.

robjohn

math.stackexchange.com/a/91961

Srivatsan

2:05 AM

@robjohn So: do you have the exact expression for $c_d$?

robjohn

@Srivatsan I believe so.

I will have to change my $n$s to $d$s.

Srivatsan

Yep, I want to maintain consistency with the other question.

robjohn

@Srivatsan It didn't have $d$, did it?

Srivatsan

Oh, but $n$ is taken, that's what.

robjohn

so $k\to n$ too

Srivatsan

2:08 AM

There should be a "vectors" tag.

@robjohn ??

Oh, you used $k$ for the number of vectors?

@rob: Quick question: it is trivial to get $c_d \geqslant 2^{-d}$, no?

Wait: in fact, even $\frac{1}{2d}$.

robjohn

@Srivatsan you mean at least

Srivatsan

Yes, at least. I revise that to at least $1/(2d)$.

robjohn

I don't know if it's easier to get that bound on the integral

Srivatsan

OK: this one goes exactly like how Potato did this. Let $X_i^+$ and $X_i^-$ be the set of vectors with positive/negative $i$-th coordinates resp.

robjohn

Hmm?

My answer is essentially like Robert Israel's

Srivatsan

2:15 AM

Now: $\sum_{i=1}^{d} |v_i| \geqslant \| v \|$ for each of the $n$ vectors $v$

Adding all the $n$ inequalities, we get:

$2d X_1^{+} \geqslant \sum_{v \in S} \| v \|$

assuming $X_1^+$ is the largest of the $2d$ numbers $X_i^+$ and $X_i^-$.

(blah blah blah)

Not sure if I made any sense to you, but I am convinced. :)

Brian M. Scott

The two comments on this answer are pretty funny.

robjohn

@Srivatsan That seems right.

Srivatsan

@robjohn Well, I just wanted an easy estimate so that I can show some work. =) However I am not going to show the argument fully; just refer to Potato's.

robjohn

@Srivatsan I am confused by the $X_i$. In one place they are a set of vectors, later it looks like a number in the inequality

Oops, I have to take the dog to the park. I will be back in about 45 minutes or less.

Srivatsan

@robjohn :=) I realised that I messed up in the second step. Hence the (blah blah blah)

It is meant to be: take all the vectors whose $i$-th coordinate is positive/negative, and sum the $i$-th coordinates of that subset of vectors

Once again, it is exactly as in Potato's post.

Sorry if I confused you. Hope it's ok now.

robjohn

2:29 AM

I'll see you in a while.

Brian M. Scott

Go park the dog. :-)

Srivatsan

2:50 AM

@robjohn @rob I posted it. I will be out for a little while. In case you posted an answer already, I will read it.

Srivatsan

3:21 AM

@Dylan Just saying hi. // I have to leave anyway for a while. Bye! =)

J. M.

@BrianMScott Cut me some slack; I don't necessarily remember all of Unicode... :D

@anon Today. As in, before 12 AM UTC...

Srivatsan

J. M.

@Srivatsan What the...

Srivatsan

@JM @JM I found this "flag" in the review section of the tools. What am I supposed to do with this?

J. M.

@Srivatsan I'd "disagree". Why is the volume of comments his business?

Srivatsan

3:33 AM

(That was Paul's post, which you certainly would've seen by now.)

@JM But wait: is there even a provision to flag the post saying that there are too many comments?

And no: I do not know who flagged it. It might not be P. Or B.

J. M.

I think that's a custom report. You know, "other"...

Srivatsan

@JM the site automatically does this?

J. M.

@Srivatsan No, not the site. Somebody flagged it; picked the "other" radio button, and proceeded to write such...

Srivatsan

@JM Oh, the "custom" option?

J. M.

Yep.

Srivatsan

3:39 AM

Hm, sounds reasonable, but look at the right side panel:

Specifically, the 1 x too many comments. If I marked it as a custom flag, then how would the system classify it (correctly) as a "too many comments" flag?

robjohn

@Srivatsan I have posted my answer.

J. M.

Peculiar. When you flag a comment (as opposed to a question/answer), your only options are "rude or offensive", "not constructive / off-topic", "obsolete", "too chatty" and "other…"

Srivatsan

@robjohn Cool, I just saw. Unfortunately, I should leave right now. (I overstayed :).) I will be back in an hour or so; I will read it then.

@JM Yes. Which is why I think it is an auto-flag.

robjohn

@Srivatsan Late dinner?

J. M.

@Srivatsan Ah, well. I'd disagree anyway...

Srivatsan

3:43 AM

@robjohn No. A drink.

robjohn

@JM "other..." covers what the others don't :-)

Srivatsan

@JM Sure. But feel free to give a different theory. =)

J. M.

BTW: Is Willie hanging around chat again, or is Mariano the only mod who goes here nowadays?

@Srivatsan No, I mean disagree with the flag... screw that report...

Srivatsan

@JM Mariano is more often seen here than the others surely. I haven't seen Willie in days (although Martin said he was spotted; yesterday, if I remember right).

I upvoted the answer, expecting to understand it later =).

robjohn

@JM Willie was here about 14 hours ago

J. M.

3:55 AM

Cool.

robjohn

I am having trouble with the time stamps. I think even though it says yesterday on his profile it was the day before, so it is 38 hours.

J. M.

Peculiar.

robjohn

The transcript says Jan 24, but the profile and the comment history say yesterday.

J. M.

Tsk, tsk...

Brian has already overtaken me in rep... I really have been away too long!

Rajesh D

4:10 AM

@JM : If you don't mind go for this

J. M.

@RajeshD Oh dear, that's one of those things that need some thought to do... I'm still getting my bearings. :D

Rajesh D

4:28 AM

I'm sure you will get all your bearings in one shot !

Mariano Suárez-Alvarez

there's a new beta site on mathematica

J. M.

Yeah, I posted about it on meta.MO too. :)

leo

hi all

Srivatsan

@JM. Help please. Can you check your moderation tools page, the flags tab? Do you find the same flag?

Hi Mariano, leo

leo

is there a function $f$ continuous in $[a,b]$, $f\gt 0$ everywhere but $\inf_{x\in [a,b]} f(x)=0$?

anon

4:35 AM

Ugh.

Srivatsan

@leo A continuous function on a compact domain attains its minimum and maximum ("extreme value theorem"). So it is not possible.

J. M.

@Srivatsan The not constructive one, or the one we discussed earlier?

leo

@Srivatsan yes, thanks,

J. M.

@anon Lots of people get short shrift for the simplest things...

Srivatsan

@JM "Too many comments."

J. M.

4:38 AM

@Srivatsan Feh, I'll disagree now...

Done.

Srivatsan

WTH? It doesn't allow me to...

How do I disagree?

J. M.

Is it still there?

Click on "flag or disagree", and pick the "invalid flag" option.

Srivatsan

Yes, done. I just glanced at the options and I thought it was one of the flag options.

@leo You're welcome.

@leo In fact, think of this related question along similar lines: Suppose $A$ and $B$ are subsets of a metric space such that $A$ is compact and $B$ is closed. Then show that $d(A,B) = \inf \{ d(a,b) : a \in A, b \in B \}$ is strictly positive.

Skullpatrol

@anon What is your opinion on this issue Anon?

leo

@Srivatsan yes, I remember that

anon

4:47 AM

The lots-of-comment-in-some-thread issue? Can you link the thread again for me?

Kannappan Sampath

@Srivatsan Isn't site kind of slow?

Srivatsan

@leo There are many proofs usually for such a statement. I asking you specifically for one that uses the extreme value theorem.

Kannappan Sampath

No answers to easy problems for an hour or so?

J. M.

@KannappanSampath Are you sure it isn't your computer?

Srivatsan

@KannappanSampath Not sure. I am sitting in front my laptop. So everything is slow =)

Kannappan Sampath

4:48 AM

@Srivatsan

Skullpatrol

@anon Do you believe that "It really doesn't get better?"

Srivatsan

@KannappanSampath What do you mean by "slow"? Slow in loading etc.? Or that not many questions and answers are posted?

Kannappan Sampath

I meant that the answers are not given to simple problems even after a long time!

Srivatsan

Then, what are you doing here? This is your chance to answer =)

Kannappan Sampath

The Minkowski for example!

Srivatsan

4:50 AM

Link?

Kannappan Sampath

I am feeling tired going to bed right away. Had an analytic night! Nothing is now working!

anon

@Skullpatrol: Of course not. By and large, it gets better for those who are bullied young. The comment thread there is very frustrating to read.

Srivatsan

Analytic night? That sounds dreadful. =)

@anon Better for those who are bullied young? What does that mean?

anon

e.g. gay teens. We're talking about the blog post I linked up there, apparently.

Kannappan Sampath

@Srivatsan One night full of analysis on metric spaces and Riemann sums!

Srivatsan

4:52 AM

@anon I got that bit. But why is it better for anyone to be bullied young?

I think I am reading incorrectly but I don't know how to read your comment.

anon

What? I said it gets better. As in, when you grow up and get into the adult world you don't have to deal with crap on the same scale, you get a social support network, et cetera.

J. M.

I mean, even if you were bullied as a kid, it can get better.

Kannappan Sampath

@Srivatsan Something interesting happened:

J. M.

@anon Or, if you grow bigger than those arses, they'll be scared of you...

Hi Jonas and Dylan!

Srivatsan

@anon Well, hopefully you are not up against some cyberbullies! =)

Dylan Moreland

4:54 AM

Hi J.M. Good to see you around here.

Srivatsan

@KannappanSampath Nice. Good for you. Are we taking names here?

J. M.

@DylanMoreland Yeah, I was away for a bit...

Kannappan Sampath

@Srivatsan what does the last sentence mean?

Srivatsan

@KannappanSampath "Will you be ok with mentioning the name of the professor?"

At least that is what I meant.

Kannappan Sampath

@Srivatsan I have no issues! It is right on my blog in his comments(well, not fully! But his email id is in the list of subscribers)! Amritanshu Prasad

Skullpatrol

4:57 AM

Cyber-bullying

Cyberbullying is the use of the Internet and related technologies to harm other people, in a deliberate, repeated, and hostile manner. As it has become more common in society, particularly among young people, legislation and awareness campaigns have arisen to combat it. Definition The term "cyberbullying" was first coined and defined by Canadian educator and anti-bullying activist Bill Belsey, as "the use of information and communication technologies to support deliberate, repeated, and hostile behavior by an individual or group, that is intended to harm others." Cyberbullying has s...

Srivatsan

Ah, that empty seat between Dylan and anon, I just realised it must be @Jonas sitting there. :)

anon

Er, does he have a transparent png as an avatar or something?

Srivatsan

@KannappanSampath Is this the person who asked you for a simpler non-structure theorem proof of that problem? Or is that someone else?

Kannappan Sampath

I am going to bed! Bye!

J. M.

@anon Either that or white...

Srivatsan

4:59 AM

@JM Except for a tiny band of light pink at the bottom.

Skullpatrol

@Srivatsan I think QED was a victim of "cyber-bullying."

anon

It can't be white, because the chat's background lattice is showing up where his avatar should be. (And this did not change when his position in the upper right did, at least for me.)

Transcript for

$Mathematics$ Mathematics