Mathematics - 2012-09-04 (page 1 of 2)

user19161

12:23 AM

@KannappanSampath What is dead?

user19161

@Rachel Hi! I was the one who commented on your blog. And I know this sounds weird, but have you considered working in another field? :-)

user19161

@gustavo How did you make the piece of music you last showed me? Some computer algorithm again?

BenjaLim

12:43 AM

@WillHunting

Gustavo Bandeira

1:09 AM

@WillHunting Nope, it's only an unknown algorithm in my head.

I was studying piano and then I had this idea.

Peter Tamaroff

1:21 AM

Anyone?

1

Q: Integrating $\int_0^\infty\left(1-x\sin\frac 1 x\right)dx$

How to show that $$ \int_0^\infty\left(1-x\sin\frac 1 x\right)dx = \frac\pi 4 $$

integral

@anon Challenge time.

Let $\{x_i\}$ be a sequence of nonegative rational numbers such that $x_m+x_m=x_{m\cdot n}$ for any $m,n\geq 1$. Show that the sequence as at least two identical terms.

anon

1:34 AM

Suppose $p,q$ are distinct primes and $x(p)=a/b,\,x(q)=c/d$. Then $x(p^{bc})=ac=x(q^{ad})$ but $p^{bc}\ne q^{ad}$.

erm, I think that's wrong - yup, needs more work

need some Bezout's methinks

Rachel

@WillHunting: Do you have a field in mind?

anon

1:55 AM

It's equivalent to any group homomorphism $x:(\Bbb Q_{>0},\times)\to(\Bbb Q,+)$ having nontrivial kernel.

actually there might be a positivity condition on the homos

user19161

@Rachel No, I am neither linguist nor logician. I was only thinking what you described seem highly specialized but I may be wrong. And it is difficult to make progress this way or even begin.

Rachel

@Will: I don't think it's more specialized than any other field of math or linguistics. But semantics/pragmatics is hard, and logic is not very popular, so it's just rare. Being interdisciplinary doesn't help, of course.

user19161

@Rachel Yeah, are you more of a math or linguistics person?

Rachel

I would love to quit and be a writer, but I don't think that will happen. And I'd have to work on these problems anyway.

I am interested in studying linguistic structures mathematically. So mostly a mathematician in that I don't really care about the real world.

user19161

@Rachel But there is so much interesting mathematics even in the field of logic itself!

Rachel

2:04 AM

If I don't find a specific person or group that I want to work with, I'll probably apply to math programs with lots of logicians and linguists around.

@Will: Like what?

user19161

@Rachel Well, I am just talking about the entirety of mathematical logic, also including set theory.

Rachel

@Will, sure everything is interesting to some degree. But I don't want to spend 5 years studying large cardinals or groups under the guise of model theory or such.

The idea of using one structure to talk about another structure is, I think, very interesting.

Especially if the structure that you're talking about consists of everything that humans can conceive of.

The kind of structures involved in this and the mappings between them are more interesting to me than anything else that I've come across.

user19161

@Rachel OK, if you find it so very interesting, then it seems that this is the road you must travel.

Rachel

@Will: I concur. :^)

user19161

@Rachel By the way, I appreciate your posts on ELU meta. I think you will make great contributions on the site.

Rachel

2:13 AM

@Will: Thanks. I wish I had more time to answer questions there.

@Will: I also get the feeling that not everyone likes it when I give slightly technical answers.

user19161

@Rachel Well, as with all SE sites, sometimes the upvoted answers or accepted answers are not necessarily correct or the best, so don't worry about votes too much.

user19161

So @rachel you know my real name right? :-)

Rachel

@Will: Jasper?

user19161

Hello @j.m.!

J. M.

@WillHunting Hello, JasWill Bieber!

user19161

2:17 AM

@Rachel Yes yes. I only noticed you on the site because "Rachel" is my favourite name for some unknown reason. :-)

Rachel

@WillHunting: I can't imagine why. Maybe if you were Jacob, it would make some sense.

user19161

@Rachel Therefore, unknown reason, hehe.

J. M.

@Rachel, you might want to ask the graph theorists/computational linguists at your institution; they may have an idea or two...

Gustavo Bandeira

@J.M. What's your avatart?

@J.M. Perhaps three.

user19161

@GustavoBandeira He is just real twisted.

J. M.

2:22 AM

@GustavoBandeira It's a quatrefoil, with some lacy decorations...

Rachel

@J.M.: I will speak to the linguists. I have been through the math department trying to get them to do independent studies with me, so I know none of them are interested in logic :^)

Gustavo Bandeira

Cute.

Rachel

I'm at Brandies. The school is very small.

J. M.

@Rachel Sometimes, you luck out and all the kids with the same likes as you are are in a school a whole country away. I understand...

user19161

@Rachel You mean Brandeis, not Brandies...

user19161

2:24 AM

Brandies are small brands, hehe.

Rachel

Hah. Yes. Slip of the fingers or something.

AsinglePANCAKE

false spoilers for game of thrones the way you spelled it!

J. M.

@WillHunting I haven't drunk those in a while... :)

user19161

@J.M. There is also Brand's Chicken Essence...

user19161

@J.M. drunk

user19161

2:26 AM

drink drank drunk

Gustavo Bandeira

@WillHunting Pink spank punk

user19161

@GustavoBandeira come came come

user19161

do did done

Rachel

Wow, this is degenerating fast.

J. M.

@WillHunting Ah, yes...

user19161

2:28 AM

@Rachel Wait till you go to the ELU room, whatever you were thinking.

J. M.

@Rachel You can always derail a train wreck... ;)

Gustavo Bandeira

@WillHunting Come into my life

user19161

@GustavoBandeira Sorry, not my type of song!

Rachel

I have been listening to German Disney songs all month.

They're actually quite chipper.

user19161

@GustavoBandeira Hey have I told you my favourite Bieber song? It is...youtube.com/watch?v=kffacxfA7G4

user19161

2:34 AM

I go wild whenever I hear this.

J. M.

@Rachel What got you into it?

Rachel

@J.M.: German songs or mathematical linguistics?

user19161

@Rachel Chat tip: You can use the left arrow to link backwards and the right arrow to reply.

user19161

Therefore, the answer is the former. QED.

Rachel

@WillHunting @Will: Ah, thanks.

user19161

2:38 AM

@Rachel Also, once you use the right arrow, there is no need to use @ anymore. It is automatic. Also note that you can use tab complete. Just type the @ and the first letter and choices will appear.

Rachel

@J.M. @J.M>: I am learning German. Songs are an easy way to get exposure and repetition.

@WillHunting It's all so fancy. :^)

user19161

@Rachel Yes, I took 9000 years to learn all this. There are more advanced chat things but that is for lesson 2.

J. M.

@Rachel Ah, yes; songs have a better way of getting stuck in your head than most other things...

user19161

@J.M. That's called an earworm...

J. M.

@WillHunting Earworms aren't necessarily songs, see... :) I'd put a few advertising slogans in the "earworm" category.

But since you brought it up: the "stickiness" of a song is indeed exploited to the hilt by advertising agencies.

Rachel

2:43 AM

Are there lots of people on both math and ELU?

J. M.

@Rachel Today is actually a slow day for this room, I'd say.

user19161

@Rachel Well, anyone can create an account instantly.

user19161

Some people just create over 50 accounts for fun.

Rachel

@WillHunting Well, active users, then?

user19161

I deleted my unwanted accounts recently, so now I am left with 3.

J. M.

2:45 AM

@Rachel On a particularly active time, you'd see at least three simultaneous conversations. Sometimes, they're even about math.

user19161

@Rachel Not really. Active is also hard to define, people come and go all the time, just like people are born and die everyday.

Rachel

@J.M. Hah.

user19161

Hey @rachel, something interesting here. testyourvocab.com I only know 18,000 words according to the site. The test takes 5 min.

Rachel

@WillHunting That sounds very low.

Meaning that I find the test suspicious, not your vocabulary. :^)

user19161

@Rachel Yes, I use only very simple words. I wonder why people know so many words and use so many words...

user19161

2:49 AM

@Rachel When I am more strict with myself, I think I only got 14,000.

Rachel

@WillHunting Strop? Hmm...

@WillHunting 30,700. I think this is way, way low.

AsinglePANCAKE

the breakdown by sat score and stuff is interesting too

Rachel

Also, it's clearly biased toward literary people. The technical vocab of scientists, mathematicians, philosophers, etc. is huge.

AsinglePANCAKE

apparently i know way fewer words than someone with my sat score should know

user19161

I stopped reading anything except math books after high school.

AsinglePANCAKE

2:58 AM

i didn't even read what you just typed

user19161

@Rachel Ah, about twice as mine. Good for you.

user19161

@AsinglePANCAKE Erm, very funny!

Rachel

@AsinglePANCAKE Hm, maybe people lied. I got an 800 on the verbal SAT, am 30, and scored with the 750 group. Or maybe I got lucky on my vocab part.

@AsinglePANCAKE Several things about the numbers seem wrong.

Also, note that if you know multiple meanings for the same form, theses don't count as additional words, which I think it very silly.

AsinglePANCAKE

@Rachel I also never read ever, so I don't know where my 800 came from. I feel like I know the standard set of words that a layperson would know, and then a bunch of obscure ones I learned in an attempt to sound smart. Anything in between those two extremes I don't know.

Rachel

@AsinglePANCAKE I read constantly, but I read non-fiction almost exclusively. The rare words there were almost all words that you would encounter reading fiction and works about literature. I think "offal" was the only one that I knew from reading fiction (Hamlet).

I learned one good word from the SAT: obstreperous. But I have only ever seen it used once.

Gustavo Bandeira

3:14 AM

@WillHunting I go wild with this: youtu.be/FdsVxI7yjV4

Sorry for the late answer - Was in a game.

Guys,we should play on OMGPOP some day.

Gustavo Bandeira

4:07 AM

@Rachel I've found this one: intechopen.com/books/how-to-link/…

@Rachel It seems it's free.

Gustavo Bandeira

6:20 AM

@FortuonPaendrag Hello, Surgery Theory guy!

Fortuon Paendrag

@GustavoBandeira: Hello! How have you been?

Gustavo Bandeira

Fine, and you?

Fortuon Paendrag

Fine too. Classes and all have begun, so I am excited! :)

Gustavo Bandeira

Yay!

What classes?

Fortuon Paendrag

@GustavoBandeira Algebraic Number Theory II, Probability, Algebraic Geometry and Representation theory. I am quite pumped :D
Also, your starred quote is very nice :)

Are you in any Math classes?

Gustavo Bandeira

6:25 AM

Me? No. I guess we aren't from the same country.

Fortuon Paendrag

De donde eres?

Gustavo Bandeira

Brazil.

Fortuon Paendrag

Oops, wrong language, then!

Gustavo Bandeira

Well, I understand spanish.

It's so similar.

►

These guys are from Representation theory.

Fortuon Paendrag

:D That's the name of a band?!

It's like the band "Axiom of Choice"

Gustavo Bandeira

6:29 AM

Haha

Repraezent - their name.

btw, what is representation theory?

Fortuon Paendrag

How much background do you have in Algebra?

So I can adjust my answer

to it

Gustavo Bandeira

Ahhh...Too ashamed to answer.

I'm still on precalculus. =/

Fortuon Paendrag

It's okay! This is why we are at M.SE! :)

Okay, so there are general algebraic objects. In some you can perform operations add and subtracting, in some you can divide by all elements except $0$ etc.

So we try to understand the elements of these objects as functions

That way, we can learn more stuff about the properties of the elements of the original objects.

Ahh. I'm not very good at this, as you can see.

Gustavo Bandeira

Algebraic objects such as monoids, rings, groups, fields, etc?

Fortuon Paendrag

Yes! Exactly!

Gustavo Bandeira

6:35 AM

Well, I guess those are some algebraic objects.

They can be divided?!

Fortuon Paendrag

I think my class is focused on finite groups, though.

I mean, in a field

you can divide an element by any other non-zero element

Like the Rationals, or the Real numbers.

Gustavo Bandeira

Example of finite group?

Fortuon Paendrag

like $\{1,-1\}$

under usual multiplication

$1*1=1, (-1)*(-1)=1$, etc

Gustavo Bandeira

The meaning of this is only a set with the integer 1 and the integer -1, right?

Fortuon Paendrag

Yes, exactly.

Gustavo Bandeira

6:39 AM

I'm a Mathematica user. This reminds me of list.

Fortuon Paendrag

Hahaha. I definitely did not think of that. :)

Anyway, it's late here, so I will be off to bed.

Gustavo Bandeira

Ok

Good night. =)

Fortuon Paendrag

We will converse again. Bye!

Gustavo Bandeira

@FortuonPaendrag When you told me that those elements could be divided.

Gustavo Bandeira

7:15 AM

0

Q: Could we make a book with MSE answers?

Several days ago, I was thinking: "This site has so much amazing answers, I guess it's possible to colect some of them and compile a book with them." I want to know if such project already exist here.

discussion

This would be cool.

Jonas Teuwen

8:14 AM

Nobody would buy.

Maybe a nice pdf. But that has a lousy search.

Gustavo Bandeira

8:25 AM

@JonasTeuwen It's not to sell it.

Michael Greinecker

10:40 AM

@Gustavo: You are still here?

hhh

10:59 AM

@GustavoBandeira You can sell it and I don't see why some people would not buy something, perhaps not material but something else? Do a game around the material XD

If you do a great search around the content, people may be just interested in it...

user19161

12:50 PM

@GustavoBandeira I doubt the usefulness of such a resource. As a site it is useful for individuals, but as a book it is a random collection of info.

N3buchadnezzar

Hello will =)

user19161

@N3buchadnezzar Hi! Enjoy your curry!

N3buchadnezzar

@WillHunting I do not have any!

Do you have a few minutes?

user19161

@N3buchadnezzar Erm, I can only help you with very simple stuff.

user19161

What is it anyway?

N3buchadnezzar

12:59 PM

I am having some difficulties with some very basic theory on vector spaces and in particular metric spaces.

Does this look overly complicated to you ?

math.ntnu.no/emner/TMA4145/2012h/exercises/oving2.pdf

user19161

@N3buchadnezzar Which part?

N3buchadnezzar

@WillHunting Basically everything!

user19161

@N3buchadnezzar Let us start with the first one.

N3buchadnezzar

I have started working on the problems, but on some problems I am not able to even start on others, I have problems working out the finer details.

For the first one, I started by showing that indeed the function have a lot of the needed properties to be a metric space.

I had problems when it came to the triangle equality

Positiveness, d(x,y)=d(y,x) was relative easy

Using $d(x,z) \leq d(x,y) + d(y,z)$ gives me
\begin{align*}
(x-z)^2 \leq (x-y)^2 + (y - z)^2
\end{align*}
that I am not able to prove.

I guess I could show that every triangle can have sides with length $x-z$, $x-y$ and $y-z$ where $x,y,z \in \mathbb{R}$, and then the equality holds by the pythagorean theorem. But again, I am not sure how to do this. Or if it is the smartest way.

John Junior

hi @BillDubuque long time no see :)

user19161

1:12 PM

@N3buchadnezzar Let x=1, y=11, z=101 for a counterexample.

N3buchadnezzar

@WillHunting So $(x-y)^2$ does not define a metric on the real line ?

user19161

@N3buchadnezzar If the counterexample is correct, then it is not a metric.

user19161

You should check it to make sure.

user19161

@JohnJunior Hi skull...

N3buchadnezzar

@WillHunting Yeah, I did check it =) But I am having problems understanding intuitively why it is not a metric space.

user19161

1:15 PM

@N3buchadnezzar Firstly, why should it be?

John Junior

@WillHunting yo

user19161

@JohnJunior Now you have decided to confuse us with that name...

N3buchadnezzar

@WillHunting I started learning about these things today a go, and my answer would be. It looks like metric spaces I have seen before blushes

user19161

@N3buchadnezzar I did not mean it is obvious to me that it is not. I am just saying that sometimes we believe something is true, but on second thoughts, there really is no reason...

user19161

Intuition plays an important role, but after intuition we still must work out the proof one way or the other.

N3buchadnezzar

1:19 PM

@WillHunting Fine! =) Thanks a huge amount for your help!

For the next one the cardinality is $2^3 = 8$ right ?

user19161

@N3buchadnezzar Yes.

user19161

Then just verify the axioms. In this case the question already told you it is a metric.

N3buchadnezzar

@WillHunting But what does for an example d(2,1) mean ?

Does it mean all the sets that contain 3 numbers, where 2 are 1 and 1 is 0 ? ooooor ?

user19161

@N3buchadnezzar OK here in d(x,y), x and y are each an ordered triple. So say x=(a,b,c), y=(d,e,f).

user19161

The distance is that between two ordered triples.

Rachel

1:25 PM

@GustavoBandeira Thanks, but I was looking for people moreso than books.

Jayesh Badwaik

@N3buchadnezzar $(x-z)^2 = (x-y + y - z)^2 = (x-y)^2 + (y-z)^2 + 2(x-y)(y-z)$
For $x > y > z$, you can see $(x-z)^2 = (x-y + y - z)^2 = (x-y)^2 + (y-z)^2 + 2(x-y)(y-z) > (x-y)^2 + (y-z)^2 $
You can work out the condition when the triangle inequality will be satisfied. Specifically $ 2(x-y)(y-z) < 0$

N3buchadnezzar

@WillHunting So $x,y \subseteq X$ !

user19161

@N3buchadnezzar x and y are elements in X, not subsets.

user19161

X is the set of triples. x and y are triples.

N3buchadnezzar

but a triple, is a set no ?

@JayeshBadwaik Awesome!

user19161

1:29 PM

@N3buchadnezzar Well, here I am just saying the $x\in X$.

user19161

@N3buchadnezzar Whether a triple is a set itself or not that is another story for another day.

N3buchadnezzar

I am also trying to learn that funky notation, so just correct me if I am using it wrong =)

user19161

For now, differentiate between subset of and element of.

N3buchadnezzar

I thought X was the set of all triples

user19161

If M={1,2}, 1 is an element of M and {1} is a subset of M.

N3buchadnezzar

1:31 PM

and if x and y are a set, then theuy should be subsets of X no ?

user19161

@N3buchadnezzar Whether something is a subset of another or not only depends on the definition of subset.

user19161

A is a subset of B means every element in A is also in B.

N3buchadnezzar

@WillHunting Since x only contains elements of either 0 or 1, and so does X, then x is a subset of X right ? :p

user19161

So in this question @N3buchadnezzar X has eight elements. An element would be (0,0,0) for example.

user19161

@N3buchadnezzar There is also some ambiguity in words here. Let us reserve "elements" for elements of a set to avoid confusion.

N3buchadnezzar

1:35 PM

Okai!

Thanks for clearifying things.

So it is obvious from the definition that $d(x,y)=d(y,x)$

user19161

In the question, think of x as say (0,0,0). Then x is an element of X.

user19161

But {x} which is {(0,0,0)} is a subset of X.

N3buchadnezzar

@WillHunting Gotcha!

user19161

So x is not the same as the set containing the element x written as {x}.

user19161

@N3buchadnezzar What?

user19161

1:39 PM

You need to use x=(a,b,c) and y=(d,e,f) for example.

user19161

Here a,b,c,d,e,f are either 0 or 1.

N3buchadnezzar

@WillHunting Since the output is the number of different numbers then $d(x,y)=0$ if and only if $x=y$.

Henning Makholm

Failed joke needs to be put out of its misery.

user19161

@N3buchadnezzar And that is because two ordered triples are equal iff each component is equal.

N3buchadnezzar

So I have proven that d is symmetric and that $d \geq 0$. Any tips on how to prove the triangle equality ?

user19161

1:47 PM

@N3buchadnezzar It can be proven with some thinking that is hard to express in words...

user19161

@N3buchadnezzar I leave you to do the thinking...

Jayesh Badwaik

@WillHunting how to denote a custom operator in TeX?

N3buchadnezzar

My head it hurts

Matt

Bleh. This is disgusting. bleurgh

user19161

2:04 PM

@Matt Chocolate sounds lovely! I guess you got the wrong brand. I don't usually have it though.

user19161

@N3buchadnezzar Have some para-acetyl-amino-phenol.

N3buchadnezzar

@WillHunting You mean some alc-oh-ol ?

;)

user19161

@N3buchadnezzar That was a painkiller!

user19161

@N3buchadnezzar Ah that too...

N3buchadnezzar

@WillHunting Alchohol is indeed a painkiller.

Henning Makholm

2:17 PM

Alchocohol?

user19161

@N3buchadnezzar Have you thought about how to do the triangle inequality?

user19161

2:30 PM

Hi @ben.

Jonas Teuwen

2:53 PM

My head. My head. My KOPF.

user19161

@JonasTeuwen Hello! Have you eaten lunch?

Jonas Teuwen

@WillHunting Yes.

N3buchadnezzar

Hmm

Is $\sin(1/t)$ bounded on $(0,1)$ ?

Jonas Teuwen

@N3buchadnezzar It is like bounded everywhere man.

anon

What's the largest value of sine you've ever seen on the real line?

Jonas Teuwen

3:07 PM

By $1$.

Holy cow.

N3buchadnezzar

@anon Like 1 million maaan, thanks

BenjaLim

3:21 PM

@anon @JonasTeuwen @N3buchadnezzar Hey

Why is this too localized? math.stackexchange.com/questions/190983/…

Jonas Teuwen

Is Alexander trolling me or do I just not understand his point? And I am being a retard.

Michael Greinecker

@BenjaLim I guess because not many people with exactly your backgrund will take exactly this course and want to even do the same project.

user19161

@anon As usual, you answer a question with a question. Brilliant!

John Senior

Hi folks

user19161

@JohnSenior Hi! You always call us folks!

John Senior

3:29 PM

@WillHunting Just seems a suitably generic form of address :)

Sabyasachi

@JohnSenior, hi!

Michael Greinecker

@JohnSenior Hi!

John Senior

I sometimes call people here mathochists or mathoholics

user19161

@JohnSenior Or rather, chathochists or chathoholics.

John Senior

@WillHunting that could be more accurate, yes

Michael Greinecker

3:31 PM

In economics, economic theorists who do very technical stuff are sometimes refered to as "mathturbators".

3

John Senior

I seem to be struggling to type accurately - fairly shattered after some hill-walking

user19161

@MichaelGreinecker I guess from the word perturbation?

John Senior

@MichaelGreinecker Don't fancy that title :(

BenjaLim

@MichaelGreinecker I know at least one other person who wants to do it.

@MichaelGreinecker What if I edit my question to ask for suggestions for a topic?

Michael Greinecker

@WillHunting Probably... @JohnSenior As the target of such terms, I doN't like it much either.

@BenjaLim I think you will probably get a few more useful answers, and then closing wouldn't be that bi of an issue.

BenjaLim

3:34 PM

@MichaelGreinecker I have edited my question.

user19161

@MichaelGreinecker Your typing is really bad!

BenjaLim

@MichaelGreinecker math.stackexchange.com/questions/190983/…

Sabyasachi

I wonder what people here specialize in.Analysis, number theory , et al

John Senior

@Sabyasachi Number theory here - but i am just a hobbyist :)

user19161

I find "specialize" a dirty word. Everything is connected!

Michael Greinecker

3:37 PM

@BenjaLim I did not vote to close. I gave you an upvote now. Personally, I h´don't have that much of a problem with localized questions if they are seldom. MO has quite many of them.

BenjaLim

@MichaelGreinecker In the sense of what kind of questions on MO?

Should I ask for references on MO?

Sabyasachi

@WillHunting, sorry if that offended you.

user19161

@Sabyasachi Your name reminds me of Kobayashi.

Sabyasachi

@WillHunting, who was he?

BenjaLim

@MichaelGreinecker I have edited my question as well as the title of it.

user19161

3:39 PM

@Sabyasachi The guy who wrote the differential geometry bible with Nomizu.

Michael Greinecker

@BenjaLim You might get good answers on MO or you might get closed, the community there is divided too. But since MO is much smaller, ideosyncracies are tolerated quite well. This is extremely localized: mathoverflow.net/questions/63221/…

BenjaLim

@MichaelGreinecker If it gets closed

I will open a meta thread

anon

3:56 PM

A Random Force is a Force, of Course, of Coarse

Michael Greinecker

Can one see a list of closed questions somewhere?

anon

Do you see either 'review' or 'tools' tabs at the top of the MSE page by your name etc?

Michael Greinecker

@anon i can access "review" but not "tools"

anon

There is a "recently closed" tab in the tools page that goes back 30 days, but it's probably only open to 10k (or more, I don't remember).

Michael Greinecker

@anon So I have to look for more rep. I was mainly curious what the questions with the lowest score where that are still visible. There is a question with 40 net-downvotes

anon

4:10 PM

The page doesn't list the scores alongside the closed Qs.

i see. thank you.

That's cool.

4:26 PM

@anon Wow. It usually shows only the three most recently closed questions.

anon

@HenningMakholm You have to switch from the "today" to the "30d" option to get the bigger list

Henning Makholm

@anon Just did. Still only 3 entries there.

anon

@HenningMakholm And then you have to click the gray sideways arrow :-)

Henning Makholm

(Facepalm)

Why did I never notice that?

Gustavo Bandeira

@MichaelGreinecker I woke up.

Henning Makholm

4:32 PM

I've spent lots of time trying to figure out whether I should vote for things in the 'recent votes' or 'most votes' first, such as not to push something out of the 3 visible entries in the other column :-(

Matt

4:54 PM

Yo to the A-team.

Do we have enough people in here for a reopen action?

I'm about to close a question but it needs to be reopened afterwards.

@anon @HenningMakholm @robjohn @J.M. ?

Link to it at least.

Here.

Okay, I'm in.

Kool.

Here.

5:00 PM

Call for votes! Reopen, please.

Will we be able to see who closed it once it's been reopened?

Henning Makholm

@Matt I think it's usually visible in the question's edit history.

Matt

@HenningMakholm Ok, good.

Henning Makholm

@Matt: Are you the Matt who used to have a red pixellated book icon as his gravatar?

Matt

@HenningMakholm Yes, sorry about that. I felt like taking it down.

@HenningMakholm Wait... book icon? It was supposed to be a pixelated head of a cat : )

I do wonder whether the people who closed the question even know what a Lie group is.

Henning Makholm

@Matt I always parsed it as a half-open book -- some kind of icon of learning in general.

Matt

5:12 PM

@HenningMakholm : D

Henning Makholm

Could you at least put something like "previously known as Matt N." in your profile?

Matt

I guess I could.

Ok, time to go, I'll see you all later!

Henning Makholm

@Matt I'm pretty sure that at least Austin Mohr and Sasha know what Lie groups are.

Sabyasachi

Hello,I just dropped by to ask a question. :)

I was wondering if Elias Stein's texts could be read before Rudin's Principles of Mathematical Analysis

(I am going by the mention of Stein's as an undergraduate text in the same breath as Spivak's Calculus and Baby Rudin

Michael Greinecker

@Sabyasachi I don't think Stein is selfcontained enough, but I'm not that familar with the book,

Sabyasachi

5:25 PM

@MichaelGreinecker, I saw it mentioned on Mathoverflow(which isn't exactly the place for me) on a thread

mathoverflow.net/questions/10282/…

Michael Greinecker

@Sabyasachi Have you already taken some analysis course? What is your background?

Sabyasachi

@MichaelGreinecker, my questions seem so quirky.It seems you are an analyst so could you please tell me the introductory books you like?(my background is Tom Apostol Volume1;I referred to Spivak for proofs of Riemann integration and also reviewed my differential calculus from it). I had contemplated studying Rudin once but I got distracted )

Michael Greinecker

Was Rudin too tough going or did you simply not like the style?

Sabyasachi

To be precise, I started Rudin.The first chapter was very easy,I found the second a bit condensed as I often confused some definitions and I was not sure if I was learning the material right. Then I had to get distracted by my school exams(chemistry!) .

After that I did not go any further.

@MichaelGreinecker,my situation is confusing, isn't it?

Michael Greinecker

Yes, chapter 2 of Rudin is rather dense. All definitions on the first page...

John Junior

5:40 PM

As an added query, may I ask if there is a "Spivak" of Mathematical Analysis?

Michael Greinecker

@JohnJunior In what sense?

John Junior

@MichaelGreinecker Difficulty.

Michael Greinecker

@Sabyasachi I think topicwise, Rudin is more general. A nice alternative is the book by Pugh. There is also a nice Dver book "Introduction to Analysis" that is much gentler.

@JohnJunior I presume you treat Spivaks Calculus as a tough calculus book. Rudin is probably the classical tough intrduction to analysis.

Sabyasachi

@MichaelGreinecker, will Pugh (along with Stein's Complex Analysis) give me the background for Rudin's Real and Complex analysis?Does it (Pugh) contain exercises more difficult than Rudin?

I want to avenge my loss to Rudin. >.<

Michael Greinecker

@Sabyasachi I'm not familiar with the complex analysis part of Rudin. I'm pretty sure it gives you the background material, the limiting factor might be mathematical maturity. Say, do you have access to a library where you can boorow these books?

Sabyasachi

5:49 PM

@MichaelGreinecker, cost is no issue.I can download the books as well

Michael Greinecker

@Sabyasachi In that case it might be a good idea to look at some alternative books once you have some basic perspective. A book that is very nice and contains reallly, realy great exercises is "Real Analysis" by Carothers.