Mathematics - 2012-05-06 (page 5 of 5)

9:00 PM

Here's a user whom I don't want in my kitchen!

t.b.

@JonasTeuwen very true. I got used to doing this with banks and officials simply because it is so convenient, even if it is against all my principles.

Jonas Teuwen

@tb In Dutch we have this saying: "Het doel heiligt de middelen".

Matt N.

@BrianMScott : D

t.b.

@JonasTeuwen in German the same: Der Zweck heiligt die Mittel.

Jonas Teuwen

It means like something: The cause justifies the means.

Brian M. Scott

9:03 PM

@JonasTeuwen English: The ends justify the means.

Jonas Teuwen

@BrianMScott Yes!

Okay, it is universal :-).

t.b.

(I assume het doel = the goal, das Ziel)

Brian M. Scott

It does: I checked.

Jonas Teuwen

Hmm, one of the former PhD students of my advisor (2009) is on an invited speakers list...

Between Cedric Villani and Felix Otto.

t.b.

I'd be scared... :)

On the other hand, it's nice, they'll divert all the attention, so you can do whatever you want...

Jonas Teuwen

9:08 PM

Yes :-).

But I would think it is very cool 8-).

leo

?

t.b.

@leo this (or similar problems) is a well known challenge in olympiad-like mathematics.

I'm pretty sure Davide will come up with a sneaky solution soon :)

Jonas Teuwen

@tb But you will have plenty of people sitting there waiting for Villani...

t.b.

@JonasTeuwen but on the up-side they'll all be sleeping to preserve the energy for the big shot

Jonas Teuwen

He's a postdoc in Bonn.

I would think it is really cool if I was "sandwiched" between Otto and Villani as a postdoc 8-).

N3buchadnezzar

9:22 PM

sup?

leo

@N3buchadnezzar inf =)

Jonas Teuwen

@N3buchadnezzar Did you eat many deer testicles today?

N3buchadnezzar

I have eaten three sandwiches today, thats it.

Brian M. Scott

Where did that come from?!

Jonas Teuwen

He's Scandinavian. They eat balls.

And goat heads!

N3buchadnezzar

9:25 PM

@BrianMScott Jonas is just crazy, goes around insulting people.

;-)

Jonas Teuwen

Did I insult you? I didn't want to do that.

Brian M. Scott

@N3buchadnezzar It's that stuff he imbibes from the 'books' in his office.

t.b.

:)

N3buchadnezzar

@JonasTeuwen I am joking, by pretending to be normal you seem like a wacko.

t.b.

@JonasTeuwen give him some products to differentiate logarithmically, he'll calm down :)

N3buchadnezzar

9:27 PM

Or make good drawings.

t.b.

No, I wouldn't dare to compete with you in that department :)

Jonas Teuwen

8-).

leo

@N3buchadnezzar How goes TikZ things?

Jonas Teuwen

@N3buchadnezzar Can you give me the logarithmic derivative of the Mehler kernel with respect to $t$?

leo

:-|

N3buchadnezzar

9:28 PM

@JonasTeuwen Its a root beer, you can aquire it at the nearest pub.

@leo Its going fine =)

leo

great

Brian M. Scott

No Lyme disease yet from the TikZ?

Jonas Teuwen

@tb Are you required by law to mention your titles in Germany? Why?

t.b.

@JonasTeuwen apparently there's a law that says that a title becomes part of your given name. So you have to display it everywhere in official contexts. Why? I don't know.

Jonas Teuwen

At least it makes you seem less like an idiot if you actually do it.

t.b.

9:33 PM

Maybe that's why?

N3buchadnezzar

So if your name is Agon, and you obtain a phd in Germany, your name is suddenly dr.agon, that seems odd.

t.b.

That'd be cool, not odd :)

Matt N.

@JonasTeuwen I don't know about academic titles in Germany but if you have aristocracy in your family then you might be Mr. <firstname(s)> Freiherr <lastname> (or Freifrau). When they abolished aristocracy they apparently didn't want to completely wipe it out so they required it to become part of people's names (even though it no longer has any meaning)

Brian M. Scott

Might be a little hard on an Eckhard.

t.b.

@N3buchadnezzar Especially if your first name's Uther Pen for whatever reason :)

Jonas Teuwen

9:36 PM

@tb Yes, I can imagine.

N3buchadnezzar

"My name is Acula, Doctor Acula, but you can call me ..."

Jonas Teuwen

@MattN Same here bro :-).

Matt N.

@JonasTeuwen : ) Not a problem here in the peasant country since we are all 100% peasant and 0% aristocracy.

Jonas Teuwen

I want to be a Baron.

Baron of Delft.

Matt N.

(not that I care one way or the other)

Jonas Teuwen

9:37 PM

Then I take one of those glasses on a stick.

Or with a cord...

(for only one eye)

Matt N.

What?

N3buchadnezzar

@JonasTeuwen Umbreliac?

Brian M. Scott

@MattN Monocle. Quizzing glass.

Jonas Teuwen

Matt N.

@BrianMScott Oh! Thanks : )

t.b.

9:38 PM

One of my colleagues in Göttingen was this guy

N3buchadnezzar

Monocle, and hat. That is what I will wear if I decide to take a post doc.

Matt N.

@tb Was Mücki also one of your colleagues there? : )

Jonas Teuwen

N3buchadnezzar

@JonasTeuwen That outfit would make you the coolest proffesor.

Jonas Teuwen

I agree.

t.b.

9:40 PM

@MattN No, that guy's in Augsburg

Matt N.

@tb Yes, now. But he's got his Master's from Göttingen.

t.b.

@MattN well, that could explain the Turkish meaning of the place my Göttingen

N3buchadnezzar

Matt N.

@tb Sweet teddy Jesus. You're judgemental today. : )

N3buchadnezzar

Whoop wopp, in todays lecture about topology we will look at nots, whop whop.

Eric Gregor

9:43 PM

Would someone tell me the precise definition of a "norm decreasing map"?

is math jax not working or is it me?

t.b.

@EricGregor $\|Tf\| \leq \|f\|$

(sometimes $\lt$ depending on whether the author thinks that decreasing means strictly decreasing or not)

Eric Gregor

the norm of the input is greater than or equal to the norm of the output?

i just see [Math processing Error]

t.b.

yup

Eric Gregor

thanks

Brian M. Scott

@EricGregor Try reloading the page.

Eric Gregor

9:45 PM

thanks @BrianMScott, worked

t.b.

@MattN about A..ingen or WM?

Brian M. Scott

@tb I can't help observing that ingen is Old Irish for 'daughter'.

N3buchadnezzar

It also means nobody in norwegian.

t.b.

@BrianMScott painful birth, I imagine... So we're even for the splork earlier today :)

Brian M. Scott

:-)

Matt N.

9:50 PM

@tb WM, I didn't realise you were implying any opinions about Göttingen.

Brian M. Scott

@N3buchadnezzar From Old Norse engi, enginn 'no one'.

Matt N.

I want to answer a measure theory question.

Jonas Teuwen

@MattN Shall I ask one?

t.b.

@MattN Insatiable Matt. You already answered two of 'em nicely :)

Jonas Teuwen

@MattN I have one! Can you give me a linear operator (non-zero!) with operator norm $< 1$?

Matt N.

9:54 PM

@JonasTeuwen If you like, yes : ) Although I've found an unanswered one I'd like to answer on main.

@tb one was actually real-analysis and nothing to do with measure-theory. And the other one also didn't involve sigma algebras and stuff.

@JonasTeuwen lol, how is this measure theory? : )

Jonas Teuwen

@MattN It are $L^p$ norms.

Matt N.

I want to rescue the thing before it gets anymore ... piled on.

t.b.

@MattN absolute continuity definitely is measure-theory! :)

Matt N.

@JonasTeuwen head asplode

t.b.

@JonasTeuwen how about half the identity?

Matt N.

9:56 PM

@tb I think it should be real analysis. But given that I've never seen it in any course I wouldn't know.

Jonas Teuwen

@tb Meh, non-boring ones. 8-).

t.b.

@JonasTeuwen $1/\pi$ times the identity, then :)

Jonas Teuwen

Okay, fine. You'll get full marks this time... 8-).

Matt N.

?

Let me do the other one first, m'kay?

Jonas Teuwen

@MattN Okay! Can you show that the Ornstein-Uhlenbeck semigroup on $L^1(\gamma)$ doesn't have an operator norm smaller than $1$?

t.b.

9:58 PM

@JonasTeuwen great! I was afraid that I'd have to uncork some complicated ugliness like 1/e times the identity :)

Matt N.

(with other I meant the actual measure theory question on main)

N3buchadnezzar

fooooooood

Matt N.

@JonasTeuwen Sure, I show that every morning before breakfast to warm up... : )

Jonas Teuwen

@MattN Okay, or any strongly continuous semigroup $(T(t))_{t \geq 0}$.

(Hint, hint)!

t.b.

@JonasTeuwen the identity?

Jonas Teuwen

10:01 PM

The operator norm $=1$ right?

I want $<1$.

t.b.

@MattN it is real analysis and measure theory. The fact that a function is absolutely continuous if and only if it is the primitive of an integrable function definitely is a measure theoretic fact and the motivation for introducing the concept

@JonasTeuwen I reiterate my previous suggestions (as generators)

Jonas Teuwen

Okay, it is a bad question. I will ponder about some other ones.

Movie now! Bai.

t.b.

have fun, bye!

Matt N.

@JonasTeuwen Have fun!

@tb Thanks for the carrot. It's sort of frustrating to have made it just about to the level of a first year undergrad.

N3buchadnezzar

Anyone know what I can mix with pommes frittes?

t.b.

10:11 PM

@MattN you're being way too harsh with yourself!

Brian M. Scott

@N3buchadnezzar On them, or beside them?

N3buchadnezzar

@BrianMScott Beside them, I need to make dinner somehow.

t.b.

running out of sandwiches?

N3buchadnezzar

I have plenty of those, but I bought too much pommes frittes for my tine freezer. And now half of it is sticking out, so I need to get rid of it somehow.

Just hope the people I live with do not get mad at me for making dinner after midnight as usual...

Brian M. Scott

@N3buchadnezzar Around here they'd likely be accompanied by a hamburger or some amazingly fatty meat dish like wings.

N3buchadnezzar

10:15 PM

Yeah, I do not have any of that. Nor do I think I want to consume it either.

t.b.

my browser complains because of the formatting abuse

Matt N.

@tb No, actually I quit that after you told me to. Now I'm just impatient. : )

@tb How so?

see you later

@leo Take it easy!

10:19 PM

@BrianMScott he was painfully reminded of this

@leo see you!

Brian M. Scott

@tb Owwww!

leo

@tb :-|

Peter Tamaroff

That is so unreadable.

t.b.

@leo As Hardy put it: Beauty is the first test: there is no permanent place in this world for ugly mathematics.

Formatting disgrace is part of that

leo

indeed

Peter Tamaroff

10:25 PM

@tb I love his Apology, but I have to finish reading it!

leo

"we are not robots"

t.b.

@PeterTamaroff I'm torn. I do like it, but I see a lot of bitterness and desperation there, which makes me sad.

Peter Tamaroff

@tb Well, it is true. It is kind of requiemish.

Brian M. Scott

Most of us, anyway. There does seem to be a Mücki-bot on the loose.

Matt N.

@tb That's why he deletes all "{" and "}" when he sees them...

: )

(I know it's not the same person)

t.b.

10:29 PM

@MattN guess so, but I dare him ever editing one of my posts. I'll open a meta thread :)

@BrianMScott again?

No: still.

No, nothing new.

Mücki-bot?

Has anyone ever pointed him to Löwenheim-Skolem?

Matt N.

@tb I can stitch you up if you like. Before the cotton wool comes out and stuff. (Although "Handarbeit" was the subject I used to hate most. Ah not true actually: second after sports class.)

t.b.

10:34 PM

@mixedmath Contrary, C2, Belsa, Mückenheim, M2 whatever.

mixedmath

oh - I see

t.b.

@mixedmath but you do have to take it seriously, his stuff was published on ArXiV!

mixedmath

whoa

t.b.

and probably on ViXrA, too. The establishment is less oppressive there :)

Zhen Lin

I'm guessing ArXiv maths isn't as controlled as the other subjects...?

Peter Tamaroff

10:40 PM

Can someone explain what he/she means with this: "It is shown that the notion of actual infinity is inconsistent, because the set of all (finite) natural numbers which it is ascribed to, cannot contain an actually infinite number of elements."

finite natural numbers?

mixedmath

I so rarely see articles on arxiv math without latex

maybe this is the first time, even

t.b.

There's no abhorrence that's not to be found in the math.GM honeypot of the ArXiV!

But the endorsement system did the trick nicely, I have to admit.

Matt N.

I'm being told that's too late and that I have to go to bed. Hope no one answer my measure theory question before tomorrow morning.

t.b.

@PeterTamaroff don't worry about it. Stick to maths.

Matt N.

Good night!

Zhen Lin

10:43 PM

@tb I'm confused. Is there or is there not an endorsement system?

Peter Tamaroff

Is that guy for serious?

mixedmath

good night

t.b.

Good night, Matt!

@PeterTamaroff he is. Is he taken seriously? No.

He's more of a nuisance

Peter Tamaroff

This simple proof is well known ...

$$ 1 +1/2 +(1/3+1/4)+(1/5+1/6+1/7+1/8)+\cdots$$
Every sum in parentheses amounts to at least 1/2. If we take infinitely many sums, we get infinitely many times 1/2 or more, so that the total sum is not finite. Counting the pairs of parentheses, we find that not less than ¡0 of them are necessary7. Counting the fractions we find that Nicole de Oresme used 2¡0 natural numbers as denominators, not aware of Cantors celebrated theorem (1) according to which so many natural numbers are not available.

Oh, that's relaxing.

But how come his work is hosted there?

skullpatrol

@PeterTamaroff He/she is merely suffering from not being able to accept a definition for infinity :-D

Peter Tamaroff

10:46 PM

Then what is his/her definition?

I honestly feel like crying. (S)he just asserted $|\Bbb N|=|\Bbb R|$.

mixedmath

you only need endorsement once, right?

t.b.

@mixedmath yes, but cr...eative minds were classified as math.GM, so they're allowed to enjoy themselves there.

Brian M. Scott

The shocking thing is that he is a Prof. Dr. and teaches mathematics and physics at the Hochschule Augsburg.

Peter Tamaroff

@BrianMScott And what was his thesis about?

Brian M. Scott

No idea.

t.b.

10:49 PM

I guess he bought it in Appenzell.

Brian M. Scott

Why Appenzell?

Peter Tamaroff

It is funny his surname translates into Mosquito Infestation (Google)

t.b.

@BrianMScott There used to be a lawyer who found a loophole which allowed him to get rich by selling degrees.

(I'm not saying WM actually did it, but that's sort of a running gag here in Switzerland)

@PeterTamaroff "home of mosquitoes" would be more apt.

Peter Tamaroff

@tb I see

skullpatrol

@PeterTamaroff Not being able to accept any definition for infinity :-D

t.b.

10:56 PM

@BrianMScott the point is that titles aren't/weren't really protected by law in Switzerland, so you could use them as long as you didn't earn money directly with them (and that isn't really well-defined). So you could claim to be a doctor of Medicine and work in a bank, for example. You'd only get in trouble if you pretended to be an M.D. and worked as a physician.

Peter Tamaroff

@skullpatrol Haha, I see.

Brian M. Scott

@tb Clever fellow, if hardly admirable.

Does give a new meaning to getting rich by degrees, though.

t.b.

Yes, definitely :)

The matter is of course much more complicated, but it's basically what it boils down to.

Antonio Vargas

Is anyone familiar with the error "no openid endpoint found" when trying to log in with MyOpenID?

t.b.

@BrianMScott here's a Spiegel online article on similar Titelmühlen, among others in Zug

Brian M. Scott

11:10 PM

Thanks!

t.b.

Ah, the Freie Universität Teufen is what I was looking for.

mixedmath

11:26 PM

Antonio, I've only that once, when wordpress (my opedid souce) was down

@Antonio

t.b.

Oh, Eric Naslund runs again!

(making it harder to cast the votes...)

Peter Tamaroff

Votes are being cast?!

Oh, NVM

Jordan

If i have a derivative what is the process to find the horizontal lines?

t.b.

set them zero?

Jordan

that could be vertical too right?

Antonio Vargas

11:31 PM

@mixedmath I finally successfully signed in. It looks like the same reason: MyOpenID was down for a while.

t.b.

@Jordan: no.

Jordan

Why not?

Antonio Vargas

@Jordan No. Derivaive = 0 means graph is horizontal. Steeper graph means bigger derivative.

t.b.

What Antonio said

Jordan

what if it is straight up, like a vertical asymptote

Antonio Vargas

11:32 PM

So flatter means closer to 0.

The derivative could be $\infty$ or undefined.

t.b.

If it is straight up then it is $\infty$.

@PeterTamaroff No, I was just saying that another viable candidate entering the race makes it harder for me to choose whom to vote for

Peter Tamaroff

@tb I see. Kannppan seems to have gotten a little upset with me in meta. I'd like to talk to him. We get along quite well, it baffled me.

Brian M. Scott

@tb On the other hand, it removes any last temptation that I might have had to run.

t.b.

@BrianMScott If you'd have followed that temptation, it would have made my decision easier :)

N3buchadnezzar

IS there any reason why people tend to write iff instead of in, in mathematical context? eg proofs.

Brian M. Scott

11:37 PM

Well, I'll admit to some small wish to try it, but I really do prefer answering questions!

@N3buchadnezzar Iff = if and only if.

N3buchadnezzar

Clever '

t.b.

No, ugly.

Didn't you watch the video of Serre you linked to a few days ago?

Peter Tamaroff

@tb I'd like to watch it. DO you have the link ?

t.b.

@PeterTamaroff here

Sorry it wasn't N3 who posted it.

Peter Tamaroff

There are 6 videos in total??

N3buchadnezzar

11:41 PM

@tb Huh?

t.b.

@BrianMScott I think most of those sufficiently involved with the site will have given it some thought, so you're certainly not alone.

Peter Tamaroff

@N3buchadnezzar There seems to be 6 videos to watch.

Antonio Vargas

@PeterTamaroff try clicking one of those "videos"

N3buchadnezzar

Dinner for 2 dollars, man I am stuffed.

Brian M. Scott

So what did you eventually eat?

N3buchadnezzar

11:45 PM

Sausages

t.b.

@PeterTamaroff I haven't watched the video I linked you to but I trusted the source. I saw the lecture years ago (on google video or whatever it was called before youtube was acquired by Google)

N3buchadnezzar

Hmm seesm like Jonas is not around, I seem to remember he wanted a question on bessel functions and merlin transformations

Peter Tamaroff

@tb I'll go by parts then, a la Jack.

Benjamin Lim

Hi guys

Brian M. Scott

@N3buchadnezzar Aha! Something meaty and distressingly fatty.

Peter Tamaroff

11:47 PM

@BenjaminLim Hey there!"

Benjamin Lim

Sorry yesterday I sounded pretty desperate with that vector calculus question

t.b.

@PeterTamaroff I think Antonio's point was that there are 6 jpegs and one video in two formats.

@BenjaminLim you honestly think you did?! :)

N3buchadnezzar

Well bear in mind I ate some healthy sausages, Chicken sausages :p

Benjamin Lim

@tb My friend just realised that the assignment is due today in like 50 minutes

Peter Tamaroff

@BrianMScott I think nothing beats $1 pizza slices after partying.

Benjamin Lim

11:48 PM

@tb I stayed up until 3.40am bashing some vec calc identities ......

Peter Tamaroff

@AntonioVargas Ha! I'm downloading now. I thought I could watch it onliune

Brian M. Scott

@N3buchadnezzar Interesting: I've not run into them. Turkey sausages, yes, but not chicken.

Antonio Vargas

@PeterTamaroff :)

Benjamin Lim

@AntonioVargas Your answer yesterday was nice :D

Peter Tamaroff

@BenjaminLim Links or it didn't happen.

Benjamin Lim

11:50 PM

I was pretty desperate for the presence of all the guys that do this kind of stuff :D :D

N3buchadnezzar

They might have been labelled as Turkey sausages. But I do not believe in what it actually says. I heard a quote once saying that if you knew how sausages were made, you would never have a good nights sleep ever again.

Benjamin Lim

@PeterTamaroff math.stackexchange.com/questions/141830/…

Antonio Vargas

@BenjaminLim Thank you :) And what a good friend you are to help under a time limit like that.

Peter Tamaroff

@BenjaminLim =)

N3buchadnezzar

I preffer not to know what is inside of my sausages. Ignorance is bliss.

Benjamin Lim

11:50 PM

@AntonioVargas It was nuts I stayed up until 3.40am

N3buchadnezzar

@BenjaminLim Its almost 2am here, I am eating sausages. What gives?

Benjamin Lim

@AntonioVargas There was all this mindless bashing like if $\vec{a} = (a_1,a_2,a_3)$ a constant vector and $\vec(r) = (x_1,x_2,x_3)$ then calculate

$\nabla \times ( \vec{r} \times (\vec{r} \times \vec{a}))$

or like bash what is

Antonio Vargas

@N3buchadnezzar Strangely I'm totally okay eating mystery "meat"

Peter Tamaroff

@BenjaminLim It is sad I can't grasp the awesomeness of it. I'm just a univ freshman.

Benjamin Lim

@PeterTamaroff Nothing is elegant here. Just some pointless algebra bash fest

N3buchadnezzar

11:52 PM

@AntonioVargas Thats what she said.

Peter Tamaroff

@N3buchadnezzar Hhahhhaah.

Antonio Vargas

@N3buchadnezzar groan

Peter Tamaroff

@BenjaminLim The niceness then. =)

Brian M. Scott

@BenjaminLim That looks remarkably boring.

user19161

Is the election starting in 7 min?

Benjamin Lim

11:53 PM

@BrianMScott Trust me you don't wanna know how long the algebra is.......

t.b.

@BenjaminLim I'm still sticking to my interpretation of the event ;-)

Benjamin Lim

@BrianMScott In that expression above each component of the curl has like 20 terms

@tb What interpretation?????????

user19161

Oh no election is in 20 hours, I thought it would be at UTC 0000.

Benjamin Lim

@JasperLoy fail

Brian M. Scott

@BenjaminLim Blech

user19161

11:55 PM

@BenjaminLim That's why you may prefer algebra to analysis.

Benjamin Lim

@BrianMScott That's why I don't do vector calculus

t.b.

@BenjaminLim The one that's responsible for a good half-dozen of question marks :P

Antonio Vargas

@BenjaminLim usually it isn't so bad if you use index notation

Benjamin Lim

@JasperLoy I don't want to get started on how many cases I had to split to calculate some Galois group

@AntonioVargas A lot of people are confused by that $\varepsilon_{ijk}$

@tb huhuhuhuhuhuhuh?

t.b.

:)

Benjamin Lim

11:56 PM

what da ya mean man?

Confused I am now@tb

Jordan

I really do not understand ln and e magic, if I have ln(x+4) can I just raise everything by e and be left with x+4?

Benjamin Lim

@Jordan yes

Brian M. Scott

Yes: $e^{\ln(x+4)}=x+4$.

Benjamin Lim

$e^{\ln x} = x$

Jordan

then wtf how does m y book get 3

Brian M. Scott

11:57 PM

$e^{\ln(\text{anything})}=\text{anything}$

Peter Tamaroff

@Jordan I always answer your questions, but if you insit maths is somehow magic I will have to desist.

N3buchadnezzar

Anyone know anything about the user Sasha ? =) (S)he seems to give out a good amount of great answers.

Jordan

It isn't magic, just similar to magic

Antonio Vargas

@Jordan I love how you're always so aggravated when asking questions. It's endearing.

user19161

@Jordan Just know that $e^{\ln x}$=x=\ln (e^x)$.

t.b.

11:57 PM

@BenjaminLim I'm just teasing you. But c'mon, "friends" coming over at 2:30 AM and asking you to do "vector calculus" for 2 hours?

2

Peter Tamaroff

@N3buchadnezzar "I'm a mix of things, a physicist by education, I earn my living as a mathematician and programmer working at Wolfram Research. I thoroughly enjoy learning and discovery process."

Benjamin Lim

@tb Well yeah I don't mind helping other people as long as I can make them happier. I don't mind sharing some of the suffering in order to help them.

Peter Tamaroff

We can pick at him/her on why Wolfram went PRO [sigh]

N3buchadnezzar

@PeterTamaroff GOD BLESS YOU, Thanks to you I do not have to read what it says on the page I linked. But can read it here! Great.

user19161

@tb Yeah, are they really "friends"?

t.b.

11:59 PM

...

Benjamin Lim