Mathematics - 2011-12-09 (page 1 of 4)

Victor

00:00

@Srivatsan - Just out of curiousity, how you people manage to solve problem in a short time

Srivatsan

@tb Thanks for pulling that out. He was 83, so a heart attack is not any shocking. [I am tempted to ask Mathemagician for clarification, but I guess I'll pass this time ;)]

t.b.

@Srivatsan As I said, nothing too spectacular. If you haven't read it, you might enjoy The man who loved only numbers. I guess for one with a combinatorics and CS background, this is a must at some point. Not great literature, but worthwhile and entertaining. Don't ask, please.

Sivaraman

@Srivatsan Not in office?

Srivatsan

@tb Sure, heard about it but not read it.

@Sivaraman No dude. Are you willing to wait?

Sivaraman

@Srivatsan :) How long?

Srivatsan

00:04

@Sivaraman Is it just you or are others joining us two?

Sivaraman

@Srivatsan Just me?

Jonas Teuwen

What is the purpose of a conference? Am I correct if I think this is mostly a social event?

Srivatsan

@Sivaraman Ok, I'll show up in 20 minutes.

Sivaraman

@Srivatsan OK. I am in my office.

Jonas Teuwen

So you guys are at the same uni? 8-).

Sivaraman

00:08

Yup.

t.b.

@JonasTeuwen No, not really. Socializing certainly is a big part of it, but much of it is exchange of ideas and working together. Usually you rarely find so many people with the same interests at one place, so having all those people around is extremely helpful. I know of many papers that started out of discussions people had when they met at conferences.

Jonas Teuwen

Yes, that is what I mean with social event. It's not really for the talks but for the people giving the talks?

But then I should find relevant conferences!

People in this country are too easy to reach.

t.b.

Both, I'd say. For me the best conferences were always those where most of the participants were also speakers. Think of looking for summer schools as well, that's also quite cool and more inspiring at your stage, I guess. I mean: people tend to be younger, and those giving the minicourses are then usually quite open for talking to students.

This also happens at smaller conferences, whereas at bigger conferences I always had some reluctance of approaching the big-shots, because everyone does.

Jonas Teuwen

Okay, thanks for the advice. I'll look for some summer/winter/whatever schools!

t.b.

Also look at the location: if it's some university or in the middle of a city, there is the danger that people disperse quite quickly after the talks. If it's some conference center/hotel in the middle of nowhere, however, ...

Jonas Teuwen

00:14

The ISEM is every year at Blaubeuren.

But this year the subject was quite boring. Semigroups in numerical analysis.

t.b.

One such wonderful place is Oberwolfach.

Jonas Teuwen

Whoah.

I definitely need to go there.

t.b.

And their library is absolutely outstanding. There are usually schools early summer, so check if there's something of interest. You live right there at the institute. There's nowhere really to go, so you're sort of in a math-camp. In the common room there's lots and lots of beer and wine for basically nothing.

Jonas Teuwen

Excellent.

t.b.

Last time I was there it was 1 Euro for a (big) bottle of beer. You can just serve yourself and make a stroke on a list.

robjohn

00:20

@Jonas: I have a web page that works. Any suggestions for a place to put it?

Jonas Teuwen

@robjohn Erm. I have a bitbucket account where I can put it.

@tb Cool :-).

Oh, that reminds me. I need to find logon information for the university personal website.

mfo.de/occasion/1224/www_view Heh Ingrid Daubechies.

"The 10th annual Summer School will be hosted by the University of New South Wales from 9 January to 3 February 2012."

t.b.

Well, New South Wales is in Australia, isn't it? :)

By the way: don't miss the photo collection on that site. There are some awesome pics.

Jonas Teuwen

Oh, it is in Australia. Silly me 8-).

Oh, I know that photo collection!

t.b.

@robjohn: the flowers of your work :)

robjohn

@tb Oh well...

Unfortunately I can't add a link to the main site that does the right thing so that it can be dragged or right-clicked to install. The main site wants a link to start with http://...

A link that starts with javascript:() will not generate a link

t.b.

00:32

@robjohn I think user-added javascript is disabled on the entire site.

robjohn

makes sense. However, I would need a place to put this link for easy install.

t.b.

Maybe @JackSchmidt would be so kind to add it to his webpage. He already has a fine collection of useful things.

Jonas Teuwen

@robjohn You mean MSE will refuse links starting with javascript? :-). Does that surprise you?

robjohn

@JonasTeuwen No, as I said, it makes sense...

Jonas Teuwen

(Sorry, I'm sleepy :-))

J. M.

00:42

Indeed; I'd be hella scared if it did...

Jonas Teuwen

But Victor made my day.

J. M.

Sheesh. Those were high school questions?

Jonas Teuwen

@JM Do vitamine pills make a good substitute for decent food? 8-).

t.b.

What are these crazy manifolds afflicted with demention? :D

2

Jonas Teuwen

:D.

J. M.

00:44

@JonasTeuwen Good grief; how come you knew what I was thinking?! :D

Jonas Teuwen

Did I?

J. M.

@JonasTeuwen I was about to say precisely that...

Jonas Teuwen

The packaging is a bit paternalistic. "A varied balanced meal and a healthy life style are important. Food supplements are no substitute for a balanced meal".

Skullpatrol

@JonasTeuwen Why did you roll back my edit?

@JonasTeuwen I am more interested in calling attention to the quotation itself and its content than who said it.

t.b.

How on earth did that discussion drift to vitamine pills?

@Skullpatrol: he explained it briefly here.

Skullpatrol

00:56

@tb improved clarity since Von Neumann is known for many quotations was the stated reason

Jonas Teuwen

@Skullpatrol That is possible too, but both is too much.

And I'm not sure if a quote in a title is good style. I should check out what the Chicago Manual of Style has to say about that.

J. M.

@robjohn Maybe not, but you got a "Necromancer", no? (I upvoted.)

Skullpatrol

@JonasTeuwen Okay then just use the quotation as the title, its shocking enough to grab attention

Jonas Teuwen

It is not that shocking, most people have seen that quotation...

robjohn

@JM Indeed I did. I have one here now to match the one I have on meta

Skullpatrol

00:59

@JonasTeuwen True, but they have no answer for it ... in over a year

t.b.

Contrary to real life, necromancy induces good feelings hereabouts :)

J. M.

Actually, in most forums, they too don't love necromancy; they don't like zombie threads. But here, it's alright to revive the buried... :D

Skullpatrol

@JonasTeuwen I respect your decision to roll it back.

Jonas Teuwen

@Skullpatrol Good.

t.b.

never mind.

Skullpatrol

01:04

@JonasTeuwen I personally don't like the quote, but it is thought provoking.

And shocking at first.

Jonas Teuwen

I don't think it is very special. It is more an opinion on the definition of "understanding" me thinks.

Skullpatrol

I thunk about it alot too

;-)

Jonas Teuwen

And I'm not really interested in Von Neumann's opinions on various things but more in his mathematics.

Skullpatrol

fair enough

Jonas Teuwen

Anyway! I'm off to bed. Need to get up in like 6 hours.

t.b.

01:09

See you, Jonas!

Jonas Teuwen

See you!

J. M.

See you Jonas.

Skullpatrol

@JonasTeuwen thanks for the explanation

t.b.

01:24

How do I convince Google books to stop redirecting me from .com to .ch and switching the language from English to German? This is super-annoying.

J. M.

Could you check what you have in google.com/preferences?hl=en ?

Especially the setting in "Languages".

t.b.

Languages: English

I don't seem to have made any settings.

J. M.

Hmm, okay. Could you go to google.com and tell me what it says on the lower right corner?

t.b.

Google itself doesn't redirect me (I use the https version). There's a link "Go to Google Switzerland"

It also remains in English. It's about Google books.

J. M.

Well, it's supposed to inherit the settings from Google... let me check again.

t.b.

01:29

As soon as I go to books.google.com it redirects me to books.google.ch. That's new.

J. M.

If you don't mind doing an experiment: could you go to images.google.com and see if you're redirected to the Swiss page?

t.b.

Okay, I'll try.

I stay on .com I'm not redirected, even after searching and clicking on images.

J. M.

Okay, clearly something funny is happening with Google Books. Does this happen on another browser?

t.b.

It's really only after requesting a particular book or book page that I'm redirected to .ch

J. M.

Holy crap; I'm now getting the redirect too...

t.b.

01:35

Yes, same on another browser. Search results are displayed on .com and as soon as I click on the book link, I'm forced to .ch

@JM I fear they're now strictifying the access rules.

J. M.

Yes, I'm being redirected to the Philippine version here. WTH?! It didn't do this yesterday...

Srivatsan

Morning, @JM.

J. M.

Hi @Sri.

t.b.

It's brand new. It didn't do it a few hours ago. Interestingly, trying with .ca I remain on the canadian site...

Hi Srivatsan, hope your dinner was good!

Srivatsan

@tb Yes, it was. Thanks. :)

robjohn

01:40

@jm try this

@tb try it, too. :-)

You can even try the link on the page. it will cause the MathJax there to render :-)

J. M.

@robjohn Works here. :) You might want to include stuff from AMS packages (e.g. \binom{}{} and Hebrew letters) for a complete test.

robjohn

when you refresh the page, the mathjax should go back to unrendered

I guess I could, but I just wanted to verify that it was working at all.

J. M.

It does; why shouldn't it? ;)

t.b.

@robjohn works perfectly fine for me.

By the way, what is this: https://d3eoax9i5htok0.cloudfront.net/mathjax/latest/MathJax.js?config=TeX-AMS_HTML ?

robjohn

Great! Now it can be installed more easily

That's where we get MathJax from, I assume.

t.b.

01:47

Yes, if I don't allow to access that page MathJaX doesn't work. But whose server is that?

robjohn

@tb: see here

J. M.

@tb It's the "secure" version they list here.

For preventing MITM and other nastiness.

robjohn

Sounds reasonable

t.b.

@JM very good, thank you!

J. M.

...and I think Cloudfront's a kosher service. ;)

robjohn

01:50

Legal Department
Amazon.com, Inc.
PO BOX 81226
Seattle WA 98108-1226
US
[email protected] +1.2062664064 Fax: +1.2062667010

Domain Name: cloudfront.net

t.b.

</paranoia mode>

robjohn

cloudfront.net is evidently owned by amazon.com

J. M.

No worries, t.b.; I did the paranoid checking too when I was mucking around with the CDN... ;)

robjohn

I added that link to the bottom of my meta post.

Srivatsan

02:05

mumbling Fair enough, but I don't agree with calling a thesis a "paper".. =)

J. M.

Well, it's not yet a paper... ;)

t.b.

@Srivatsan and why restrict to papers?

Srivatsan

@tb Because the OP wants to. I have no clue why =)

t.b.

I was wondering about that. Oh, well, whatever.

Srivatsan

Yes, I understand.

@tb Ouch, the question is deleted now.

robjohn

02:17

@JM There, I added some more MathJax stuff. If you have other suggestions, let me know.

J. M.

Great! Thanks for hosting this!

robjohn

No problem. It's nice to finally get MathJax on the chat.

Wow, my rep growth has suffered from all this mucking about with MathJax. I'll have to get back to work :-D

Hey @Victor, did you ever get the MathJax bookmark installed?

@Victor: go here and use the "alternative installation link" at the bottom of my post.

I have to go walk the dog. BBL

J. M.

See you, rob.

QED

@Srivatsan, I deleted it because it was a duplicate

Victor

@robjohn - even i right click it, it doesn't show "add bookmark"

robjohn

02:30

@Victor Is there a choice "Bookmark this link" or something like that?

Victor

@robjohn - i don't know "bookmark this link" is under which menu

QED

you need to make a bookmark then paste "javascript: .." in the URL for it

Srivatsan

@QED If it's duplicate, we close it. Why delete the question altogether? FWIW I thought your question was more well-written than the original.

Victor

@QED - i have no experience to use computer

robjohn

@Victor when you right-click on the link a contextual menu should appear with several choices. Do any of those choices say anything about adding a bookmark or bookmarking a link?

t.b.

02:33

@Victor: is there "Add to Favorites?"

Victor

@tb- yes

t.b.

That's what you're looking for.

Victor

@tb - just add it to favorite?

t.b.

Yes.

Have you added it?

Victor

@tb - what else i have to do?

t.b.

02:37

Click it (or select it from the menu) wherever you have put it.

Then this should compile:

$$\int_{-\infty}^{+\infty} e^{-x^2}\,dx = \sqrt{\pi}$$

Victor

@tb - it doesn't shown but the text shown on the link

t.b.

I'm not sure I understand.

Did you go here, right-clicked on "render MathJax" and selected "Add to Favorites"?

Victor

@tb - the formula compile on the other link but not compile on the chat...

t.b.

You created your favorite? Then you clicked the favorite while you're here in chat?

Then it should compile the above formula

Victor

@tb - no, it doesn't

t.b.

02:48

I can't help you if you don't answer my questions.

7 mins ago, by t.b.

Did you go here, right-clicked on "render MathJax" and selected "Add to Favorites"?

Victor

@tb - yes, i did

t.b.

So, you got this new favorite. While you're here in chat, click it or choose it from the menu.

What happens?

Victor

@tb - thanks a lot

t.b.

You're welcome. Now everytime you enter chat here, do what you just did (click the favorite or choose it from the menu). You will see the formulas compiled, such at this one: $$\int_{-\infty}^{+\infty} e^{-x^2}\,dx = \sqrt{\pi}$$

Victor

i have a problem for the answer given by Americo in this problem: math.stackexchange.com/questions/37044/… why there are middle point of the cell where the cell is irregular shape?

@tb ?

J. M.

03:12

Well, I need to be outside for a few. See you guys.

Srivatsan

@JM, For this question: math.stackexchange.com/questions/89799/…, the [convergence] tag is relevant too. Can you add that as well? Thanks.

since you already touched that post =)

Victor

@Srivatsan - is the answer by mike on the link i give is just approximation because the shaped area is not rectangular?

Srivatsan

@Victor No, this is exact. When you take smaller and smaller such pieces, they look more and more like rectangles.

Victor

@Srivatsan - How would you prove that?

Srivatsan

@Victor Well, the formula for the change of variables is intuitive, but the proof is not that obvious, I believe. [I am not sure I have seen a proof myself.]

Victor

03:20

@Srivatsan - is this a postulate?

Srivatsan

But here's one thought: You're right that it's not a rectangle; so one needs to worry about the error in treating it as a rectangle. Now if the error is sufficiently small (for instance, if it is lower order term compared to $\Delta r$ in Mike's answer), then we can ignore it.

@Victor What do you mean by a postulate?

Victor

@Srivatsan - in another word, a axiom

Srivatsan

@Victor No, of course not. It needs a proof, and it has a proof. I don't know the proof, so I cannot tell it to you; that's all.

Victor

@Srivatsan - thanks

@Srivatsan - By the way, what decide a "theorem" is axiom or not?

Srivatsan

And I do think it is unlikely you'll see a proof until in an undergrad or grad course. That said, you can try to understand the meaning behind the formula at least.

@Victor Sorry, this is too vague a turf for me to be comfortable with. A theorem is not an axiom, and that's just the definition of a theorem. I do not know what you mean by which theorems are axioms.

robjohn

03:27

@tb thanks for helping Victor while I was gone.

Victor

@srivatsan - when i say theorem , i mean it is proposition

t.b.

@robjohn: no problem (almost). Congrats for your shiny new generalist badge!

Srivatsan

@robjohn How's your kitten [whose hip needed healing]?

Victor

@robjohn - You are nice, thank you!

robjohn

@tb: I have a new badge? I will have to look!

@tb the kitten is doing well. We visited the vet on Monday, and her hip is healing, but she needs to be confined for another few weeks.

Srivatsan

03:29

Congrats, @robjohn.

robjohn

@Victor: you're welcome.

@Srivatsan thanks :-)

Victor

@robjohn - out of curiousity, is bring the cat to a vet is more expensive than the cat?

robjohn

@Victor considering the kitten was rescued from the street, yes :-)

Srivatsan

@Victor He did not buy this particular kitten. He saw her wounded by the road, saved her, and took her to the vet.

So, by definition, yes. =)

Looks like I just repeated robjohn's comment... =)

@robjohn Do you guys give names to your pets? [What's this one called?]

t.b.

@Srivatsan I'd say that's an axiom.

Srivatsan

03:33

@tb =)

Victor

Actually what time it is on your people's side, it is 10:30 on my side

t.b.

4:30

robjohn

@Srivatsan Yes, we do. We haven't settled on a name quite yet. possibilities are Smoky, Misty, and Califa.

@Victor AM or PM?

Victor

PM

Srivatsan

@robjohn Do we get to vote? I like Misty. =)

robjohn

03:35

it is 19:34 (7:34 PM) here

Srivatsan

It's 10.30pm here.

Victor

@tb - are you in california and @robjohn - where are you?

robjohn

Califa (Cali for short) is the name of the street on which we found her.

@Victor I am in Los Angeles, California

Srivatsan

@Victor Oh, tb's not in the US. And it'll be 4.30AM wherever he is.

@robjohn So you are in LA. I guessed right then. =)

t.b.

@Victor: central Europe, 4:30 AM

robjohn

03:37

@Victor it sounds as if you are on the east coast (Canada or US)

t.b.

Where are you?

Victor

NY

@tb - are you professor always traveling?

Potato

@robjohn thanks for your help earlier sorting out that stolz angle thing. I eventually got it another way using the arctangent of the angle, also.

t.b.

@Victor: No, I'm pretty static. I live here.

Srivatsan

@robjohn I assumed Califa was short for California. =)

robjohn

03:40

@Potato Did you see the diagram and the following derivation?

Potato

Yes.

I had logged off by the time you posted it, but I saw the transcript.

robjohn

@Srivatsan understandable, but I don't think I would name my kitten for the state.

Victor

Allow me to ask this again: is there a way to determine a statement is a axiom or not?

Srivatsan

I feel like flagging something tonight. Any posts?

Potato

@Victor what axiomatic system are we working in? ZFC?

Srivatsan

03:42

@robjohn Um, it could be someone else who chose that name, right? :D

robjohn

@Victor axioms are thngs that are assumed true without proof.

everything else is proved from them.

@Srivatsan It could be, but my wife is very bad at naming things. Her D&D characters were named Tall, Short, and Stacie's Cleric.

So she leaves the naming of things to me :-)

Srivatsan

@robjohn Imaginative :) [although I don't know what the third name refers to.]

Potato

Name the cat Abel.

robjohn

@Potato dare I ask why?

Potato

It's mathy but not overly so.

Or just choose a Fields medalist.

robjohn

03:45

Terry Tao is our local Field's Medalist...

Srivatsan

@Potato If I have to choose one from this category, I would vote for Terry.

Victor

@robjohn - May be the name of your doctoral thesis?

Srivatsan

[I guess I should be a bit faster in typing :( ]

robjohn

@Srivatsan I thought it was interesting that we chose the same person.

Srivatsan

@robjohn Oh, I am a big fan. =)

Victor

03:47

@robjohn - is terry tao charming to you? why?

robjohn

@Victor He is local (at UCLA) and he has a very good blog.

Potato

Sadly for the the ladies, he is also married.

robjohn

@Victor: I taught math at UCLA from 1986-1988

Victor

@robjohn - is he your student?

Mr_CryptoPrime

The ellipse 18x^2+2x+y^2=1 has its center at the point (b,c) where b=____ and c=____?

I completed the square to get the following equation:
18(x+1/18)^2 + y^2 = 19/18
However, I don't know how to get it to the final form x^2/a^2 + y^2/b^2 = 1? I could just input it into wolfram|alpha, but that doesn't help when I can't use it on the test and need to it algebraically. Can anyone help? Thanks.

robjohn

03:50

@Victor Oh, no. But we had the same advisor at Princeton.

Srivatsan

@robjohn Oh, I completely forgot about that.

robjohn

At very different times.

Victor

@robjohn - it wil be funny if you called your dog terry when you come across with tao

Srivatsan

@robjohn I like him because he is one of the few FMs, (a little part of) whose work I can understand at the current level of my knowledge.

Victor

@Srivatsan - How many years after you have graduate from phd?

Srivatsan

03:56

@Victor Oh, I do not know (and don't quite care) what inferences you're going to draw from whatever I said. It mainly is due to the fact that I work in combinatorics and computer science, not mainstream mathematics.

@Victor And I don't know the answer to your question. [Honestly.]

Potato

@Srivatsan He wants to know for how many years you have held a PhD.

Victor

@Srivatsan - i don't really care actually, it is just interest to that question

Srivatsan

Oh, sorry, I thought the question was: how many more years till I get my PhD. I haven't graduated yet.

Victor

@robjohn - is there anyway to solve this in chat.stackexchange.com/transcript/message/2663013#2663013

Srivatsan

Alright, I'll see you boys tomorrow.

t.b.

04:05

See you @Srivatsan

Asaf Karagila

05:37

@tb You tharrr?

robjohn

05:51

@AsafKaragila Hey there :-)

Asaf Karagila

Hey robjohn.

I saw an update on the ChatTex post. You should add a changelog :-)

I gotta run, my advisor is meeting me in 30 minutes and I still have to get ready.

See you much much later :-)

Potato

06:55

Why is the fact that A, B are open key in this exercise? Suppose A,B are open, f holomorphic on A, be holomorphic on B, and f=g on A intersect B. Show there exists F holomorphic on A union B with F=f on A and F=g on B.

We don't usually talk about functions holomorphic on closed sets so I don't see what the deal is. Just let F=f on A and F=g on B, right?

But there is some subtlety I am missing apparently.

J. M.

Bah, first they make it hard to copy links from Google search results, and now this Google Books nonsense...

@t.b.: Something you can try the next time you need to use Google Books in English: replace the .ch with .com, and insert a hl=en& after the question mark to force the English interface.

(Maybe I should write a bookmarklet...)

Transcript for

$Mathematics$ Mathematics