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8:00 PM
Good, @BalarkaSen.
 
Because none of my algebras are particularly strong
 
OOOOOOOO..... Topology discussion
 
A lot of "examples" in topology come from $\Bbb R^n$, and this is an inner product space-which induces a norm, which induces a metric.
 
@JulianRachman I don't think every discussion here is beneficial.
 
No. It definitely think that this discussion will not help me at all. But I just heard topology and see if I could help or do something
:)
@ABeautifulMind
 
8:01 PM
So one can gain a "concrete" example of how "nearness" is related to our ordinary notion of "close together in physical space"
 
Yeah, sometimes people listen to some discussion and get all the wrong ideas about something.
 
@MikeMiller My prof recommended Hoffman-Kunze for LA and Spivak (calculus on manifolds) for mult. calc. D'you think they are good?
 
FINALLY, I FINISHED THE PROOF!!!!!!!!! This took me one month, I can't describe how relieving it is to not have it hanging over me anymore :D
 
Hi @Julian
 
Hoffman-Kunze is good. The typography is terribad, but the presentation is nice, idea-wise.
 
8:03 PM
@Balarka Hello
 
Thanks, @David. I'll try it out then.
 
Spivak is a must-have
 
I think Spivak's calculus on manifolds is awful.
 
Oh, on manifolds? Nope, nope nope nope nope
 
I don't really know linear algebra books.
 
8:04 PM
@Balarka WHat you up to?
 
Spivak's "calc on manif" is like a reader's digest version-it's not terribly in-depth.
 
@teadawg1337 It's just a multivariable calculus book. There's not really any manifolds. I still think it's bad.
 
Hmm, OK. What would you recommend for a thorough study of mult calc/diff geo, @Mike?
 
Stewart's Calc ET (7E) is pretty decent for multivar up to the chapter on vector calc
 
"Big" Spivak (the 3-volume set) is generally recognized as far better
 
8:06 PM
@Bal Someone gave me Hubbard's Vector Calculus, Linear Algebra, and Differential Forms and told me it was good
 
I am familiar with basic calculus. I just need something that'll guide me through prereqs and basics of diff geo.
 
That assumes you know multivariable calculus, @DavidWheeler.
Lee's smooth manifolds book is good. You mainly need to learn the implicit and inverse function theorems. It wouldn't hurt to see a discussion of div-grad-curl to prepare you for what comes later, but it's not really a big deal.
 
@DavidWheeler What is big Spivak?
 
If you don't want a huge tract, and mostly want to learn some topology, then get Guillemin-Pollack's book, "Differential topology".
Still need to know the inverse/implicit function theorems, and it won't tell you everything you need to know about smooth manifolds, but it's more in line with what you've been doing.
Ask Ted where to learn multivariable.
 
I am not sure if I care about just topology. More to the point, I want to understand forms.
OK.
 
8:08 PM
@ABeautifulMind amazon.com/… is volume 1
 
@DavidWheeler That is 5 volumes.
 
Ted says Spivak is really good
 
Spivak's calculus, I assume.
 
Mhm
 
That's, I think, pretty much universally agreed. Taste in the 5-volume set depends on one's personal taste; I don't like it.
I don't think Ted does either.
 
8:10 PM
@ABeautifulMind well, i'm not good with big numbers :P
 
Basic calculus I studied from Piskunov. Not well-known, but I liked it.
 
I should read Hubbard-other people seem to like it
 
@MikeMiller alternative?
 
@Ted!!
 
8:13 PM
hi @Balarka
 
Not very "deep", but adequate, I suppose
 
Heya @Ted!
 
@TedShifrin Recommend me a mult. calc. book. A good one.
 
Balarka needs some advice on a multivar-calc book
 
We've got the chat in its book obsession again, so I'm out. Morning, @Ted.
 
8:13 PM
Hubbard is great for professors who know what's in the book already, @David :P
g'night, @Mike
obviously, mine, @Balarka
 
Superb. Send me a copy. :P
 
...
 
waits for smacks
 
I'd go broke doing that for everyone in here, @Balarka
 
@BalarkaSen smacks
 
8:15 PM
Me too! I'll give you a complimentary review (pun intended).
 
Hello Ted.
 
hi Jasper
not a supplementary one, @David?
 
@ABeautifulMind hello
 
Yeah, but I'm special, @Ted. The only one in the whole world who's gonna study mult. calc. after algebra, alg. top., etc.
:P
 
@user153330 Hi.
 
8:16 PM
@TedShifrin Well, depends on how much free time I have....
 
Hello @TedShifrin
 
@ABeautifulMind you still recognize me :p
 
no, @Balarka, you're raising a whole cohort of teenagers here who seem to want to do the same thing
mr eyeglasses -- how many identities do you have now?
 
@TedShifrin Well since people keep referring me to eye*s I might as well just accept it
 
not my fault if people want to copy my extremely unique and extremely bad study plan.
 
8:17 PM
I thought I was the only one
 
@TedShifrin me too
 
well, yeah, @Balarka, it is
 
I didn't know how to ping you when you have the weird font, eyebrows
 
mr eyeglasses, did you ever restudy that linear algebra?
 
Shoot I missed the memo. Again.
 
8:18 PM
@TedShifrin Yes
 
I have no idea how to ping Hippa anymore, @Mike
 
I tried learning topology before learning multivar, and it just all went over my head.
 
Me neither, but I suppose nothing is lost :D
 
@TedShifrin Turns out it was very helpful for my number theory class (lots of linear algebra involved)
 
and you still really haven't learned multivariable, @teadawg ... you've learned engineering math
 
8:18 PM
It made a lot more sense with real analysis
 
@teadawg1337 yup
 
@Ted I don't have the resources to study real multivar yet
 
@teadawg1337 why not
 
my physics teacher (also named Wheeler) used newtonian notation almost exclusively. it was strange.
 
no, first you have to pass Calc I, @teadawg facepalm
 
8:19 PM
ok, @Ted, then recommend me something that can be pirated evilgrin
 
@TedShifrin: I've finished writing my talk, though I still have to compess my notes into what I'll bring in with me. I've finished all the various homeworks I've got due in the future, and the next PDE homework hasn't been sent out to us yet. I have no idea what to do with myself!
 
I still have a 100 in Calc I
 
Literally every book can be pirated, @BalarkaSen.
 
I know nothing about what can and cannot be pirated, @Balarka, and nor do I wish to
 
I mean that has a pirated copy.
 
8:20 PM
You still have plenty left to learn, @Mike ... At least, you whine every time I mention something you should learn.
 
Yes, yes. I'm just hesitant on starting anything new because I'm going to be busy again starting Monday, and I don't want to have to start n stop
So maybe it's beach weekend.
 
@Pedro hi.
 
I messed up my back, so doing all the schlepping and organizing for the people who're going to come empty out my house is not fun :(
 
Hello @PedroTamaroff
 
8:22 PM
oh, @Pedro transmogrified again?
this is the California look?
 
He has hand-eyes
 
The trouble with pirated versions of textbooks: 1) they are often scanned, which is sub-optimal. 2) people like to put malware in the files.
 
I guess so.
 
@MikeMiller except shifrin's books
 
@Pedro are you doing covering spaces?
 
8:22 PM
so how's my new home city, @Pedro? You're supposed to be playing tourist in the gorgeous weather
I found a .pdf of one of them, @user153330, which looked like it must have come from the publisher (who of course denied it vehemently).
 
I could get both linear algebra and differential geometry within the next minute, @user153330. Of course, I won't tell anyone how, as I strongly advise using the local library instead.
 
Differential geometry is not pirated, @Mike. It's purposely freely available.
 
@Ted I finally finished the problem with polylogs today, so now I can put aside more time to watch your lectures
 
I don't have a local library, on the other hand.
 
You go to that one university...
 
8:24 PM
@MikeMiller Some people like me have no library to go to.
 
yeah a google search on Ted yielded this as #1 result: alpha.math.uga.edu/~shifrin/ShifrinDiffGeo.pdf
 
LOL ... I have never been bitten by this bug that you and chris'ssis share, @teadawg.
 
@MikeMiller That hasn't got it either. I checked.
 
@Balarka: If you go to university classes, you have a university library.
 
Can't you request them to order it?
 
8:24 PM
@BalarkaSen I'm reading about them.
@MikeMiller Physical books are so much better, yes.
2
@TedShifrin Yeah, the weather is ridiculous. It's allegedly winter here, but we have like 80°F.
 
Who's the star fanatic today?
 
@TedShifrin Well, if you don't want to send it, okay. Just recommend me something else.
 
@Pedro: It'll be warmer in SF, typically, in the winter than often in the summer, too.
 
Not I, I only star things I find star-worthy (I'm pretty harsh in that regard).
 
@TedShifrin It's not as much a bug as it is a tendency to become obsessed over the little details
 
8:27 PM
I think I've starred two things here in all the time I've been here.
 
@PedroTamaroff You've studied Galois/normal/regular covers yet?
 
how to write SQRT symbol in computer?
for example sqrt 9 = 3
 
@BalarkaSen Nope.
 
@TedShifrin I think one was something Old John said, and the other was something I said.
 
In LaTex the command is \sqrt{ }
 
8:28 PM
ok
 
@MikeMiller The other one was something about me. :P
 
How can I find a transformation matrix from B TO A if B = {t1,t2,t3} (B is basis of vectors space over R3) , and A = {s1,s2,s3} s1 = t1-t2 , s2 = t1+t2, s3 = t1+ t2+t3?
 
I hope it was suitably mean, @BalarkaSen
 
sqrt(13*sqrt(13)*sqrt(13)*sqrt(13)*sqrt(13)*sqrt(13)*sqrt(13)......) = ????
 
To render latex on this site, you enclose with dollar signs
 
8:29 PM
I think it was. Well, I have improved considerably (I think) from my past self.
 
sqrt(13*sqrt(13sqrt(13sqrt(13sqrt(13......)
 
@Ali.B: You mean it's a transformation from $\Bbb R^3$ to $\Bbb R^3$ given by sending $t_1$ to $s_1$, etc.?
 
Otherwise I wouldn't have considered studying forms (and to do that, mult. calc.)
 
well, if you do my book, @Balarka, you learn forms in order to integrate on curves, surfaces, manifolds ... :P
But you don't learn forms in terms of tensor products.
 
If you are doing it an infinite number of times, it's going to be different than doing it a finite number of times @hilmanshini
 
8:30 PM
@David: I presume he/she means the limit of the sequence ...
 
@TedShifrin I hope so, yes
 
@TedShifrin I'm trying to translate the question from hebrew to english that's the closest I can get.
 
well, you're not going to send me that book, so no point in trying to get me to, @Ted.
If you send it, I'll happily study it.
 
@Balarka: If I start sending you something, then I have to send something to dozens of people on this site.
 
8:31 PM
@TedShifrin: Are vector bundles cancellative before passing to K-theory? i.e., if $T \oplus N \cong T \oplus N'$, is $N \cong N'$?
 
Noooo @Mike.
 
Doubted it.
 
@hilmanshini that equals $13^{1/2+1/4+1/8+...}=13$
 
Thanks. Ex?
 
You know a very simple example, sir.
 
8:32 PM
@user153330 so the result is 13 ?
 
@user153330, I hope you have a typo there.
 
@TedShifrin well, sigh
 
How does my answer here get downvoted: math.stackexchange.com/questions/1179918/…
 
@TedShifrin oh well
 
then definitely i need to study from somewhere else.
 
8:33 PM
what is 13$?
 
The series you wrote, @user153330, diverges.
 
@JulianRachman Someone clicks on the "down arrow"?
 
oh expression $<<expression>>$
 
@hilmanshini $\sqrt{x\sqrt{x\sqrt{x\sqrt{x\sqrt{...}}}}}=x$
 
Just giving the answer isn't much help, @teadawg :P
 
8:33 PM
@David I meant why
 
@TedShifrin yes, i do too many faults when i have headaches
 
oh ok
 
@TedShifrin should I rephrase the question better ?
 
@hilmanshini It makes more sense if you square both sides
 
and yikes your book is too costly, @Ted
 
8:34 PM
@JulianRachman You may never know. My advice: don't worry about it.
 
There's a lot of effort and knowledge in that book, @Balarka.
 
It's true for vector bundles on the circle, @Ted :P But there aren't so many of those.
 
@teadawg1337 how can you calculate that?
 
@Mike, try writing the trivial bundle of some rank on $S^2$ two different ways.
 
@David Why? It pisses me off when oyu dont know who downvoted your answer
 
8:35 PM
@Julian: Plenty of people have downvoted me, and you know I'm beyond reproach :D
 
because then I can question them
@Tede haha ya. But you get like 20 upvotes each answer
 
@JulianRachman Individual events have a limited overall effect. Reputation, and community standing are aggregates.
 
Good point, @Ted. Thanks.
That's a great example.
 
No, @Julian, plenty with 0.
 
@David ok I gues
 
8:36 PM
@JulianRachman Voters may not be interested in explaining their motives.
 
@TedShifrin I appreciate the amount of effort, but, well, OK.
 
@Ted ok. Well. I feel better
 
$x\sqrt{x\sqrt{x\sqrt{x\sqrt{...}}}}=x^2$
Look at the initial equation. Make sense now?
 
@David but they shouldnt be downvoting with no reasoning
 
I'd have said "consider Hatcher", but that may have been impolite.
 
8:37 PM
pinged the wrong person
 
But, @Julian, I agree that it would be a better world if the person commented or asked a question to register what's wrong.
 
@TedShifrin try this one in one line (let me know if you doubt it) $$\int_{-\infty}^{\infty} \frac{e^{a x}}{1-e^x} \ dx=\frac{\pi}{\tan(a \pi)}, \space 0<a<1$$
 
You did say it, @Balarka.
 
@Ted yes. it really would
 
I recently downvoted my enemy on here but didn't comment (because he would have exploded in another personal attack/rage); I just added a correct answer. :P
 
8:37 PM
@JulianRachman People don't always do what they "should". And what "should" be done is usually subjective-so people often disagree on that.
 
@Ted so what are you up to?
 
Sorry about that @MikeMiller
 
@David ya...... sadly.....
 
Resting my back ... I'm busy getting my house ready to be dejunked so I can try to sell it.
 
Backache is not good, @Ted. Get well.
 
8:38 PM
I personally appreciate it when people say what they feel is lacking in an answer of mine, but it doesn't always happen.
 
and this is for everyone: Should I just take down my "mathematics advisory" proposal and just make it into a chatroom?
 
I often make comments to criticize or question, but I rarely downvote unless the answerer is just stubborn or unresponsive, @David.
 
If V is a 3 dim vector space over R, and B ={\alpha{1},\alpha{2},\alpha{3}} is a basis set of V, and A={\beta{1},\beta{2},\beta{3}} , \beta{3}= \alpha{1}+\alpha{2}+\alpha{3}, \beta{2} = \alpha{1} + \alpha{2}, \beta{1}= \alpha{1} - \alpha{2}.
what's the transformation matrix from B to A and the transformation matrix from A to B?
 
@Ted haha thats nice. You know, when my parents say to clean my desk every week, I just say "I am an aspiring mathematican" and then I show her a picture of like terry tao's desk
 
I had an answer down-voted recently. My answer was correct, but no one left a comment, so I have no idea why they did it. Perhaps they felt it was "too helpful". In that case, I would understand, even if I didn't agree.
 
8:40 PM
It's good to know I have no enemies. I hope Ted was not referring to me. I mean I wouldn't invest my energy in a waste of time, I have serious research to do.
 
@Chris'ssis Everyone knows Ted's enemey is Rene.
3
 
@BalarkaSen I did not know that.
 
@Ali.B: you're making it more confusing. You're asking for the change of basis matrix?
 
Someone's star-happy today...
 
yes but I need to change to an exact another
 
8:42 PM
Of course, this is the matrix of the linear map from $\Bbb R^3$ that carries respective basis vectors to respective basis vectors.
 
@BalarkaSen Never heard of him.
 
@Ali.B: The columns of the matrix are the coordinates of the "new" basis vectors with respect to the "old" basis.
 
any more possible question suggestions for my proposal? area51.stackexchange.com/proposals/82510/mathematics-advisory
 
Yes, this star-happiness needs to abate.
Some mathematicians are extremely neat, @Julian.
 
@TedShifrin Good luck enforcing that view.
 
8:43 PM
hmm any exact tutorials on how to do it ?
 
huh? @David
oh, that
 
@Ted the only mathematican that I know that is neat is Jacob Lurie
 
Just because you feel star-happiness is undesirable doesn't mean you can obtain a community consensus on this.
 
If $s_1=t_1-t_2$, the first column of your matrix will be $\begin{bmatrix} 1 \\ -1 \\ 0\end{bmatrix}$, @Ali.B.
@Julian: Several of my colleagues are exceedingly neat. I'm medium.
 
Ok. Well, i am the messy half
 
8:45 PM
@JulianRachman gah, category theorist.
 
ah I think I understand now
 
I have other colleagues whose offices are literally a pig sty ... and often smell like one.
 
My handwriting is impeccable, but I practically leave a mess wherever I go
 
@Balarka lol emphasis on "category" :)
 
8:45 PM
Hello my friends :-)
 
@teadawg: Anyone call you Pigpen?
 
so the transformation matrix is E1 . E2 .E3 etc when multiplied by matrix A gives you B
 
well, I guess I have to go sleep.
 
Good, @Ali.B.
 
Nope @Ted, you're the first
 
8:46 PM
Pigpen
 
No, I don't think that's right, @Ali.B.
night, @Balarka
 
:-O eyes without a face!
 
hi skull
 
@Ali.B The "formulas" of the $\beta$ in terms of the $\alpha$ actually gives you an algorithm for determining the change-of-basis matrix, as Ted noted above.
 
<--- a bit sad for not being able to persuade Ted to send the book
 
8:48 PM
Consider my position, @Balarka. If I considered doing it, you and your loud mouth would be telling everyone and everyone would be begging for it. Not going there.
 
@BalarkaSen Perhaps he might have been more willing to do so if the request was private. But now, we all saw it, and that backs him into a corner.
 
ok I still don't understand perfectly so I will go search for more information solve the example above and give you my solution, if you'd be kind just to check it it's right by then.
 
It's partially my fault, I think
I brought it up a couple days ago, and a lot of people have been asking since
 
Try simple $2\times 2$ examples, @Ali.B. If I tell you the A basis is $(1,1)$ and $(2,3)$, figure out by hand what the matrix has to be that takes the standard basis to that.
 
@Ali.B You can devise a pseudo-test, by choosing some test bases to check your answer.
 
8:50 PM
Back to my research. BBL
 
Gah! What Ted said. grumbles
 
LOL ... mediocre minds on the same track, @David? :)
 
Oh well. Anything else you'd recommend, then, @Ted?
 
@ᴇʏᴇs without a face
 
If Ted recommends his book, you might try actually locating a copy. It might not be that hard.
 
8:52 PM
"locating"?
 
My book and Hubbard and Hubbard are sort of the only ones in this particular market. There are books like Williamson, Crowell, and Trotter (from 30 years ago) that are not at the same level.
I think mr eyeglasses spent a whole homework night finding his newest avatar :P
 
@TedShifrin Yeah, Williamson et. al. don't even hardly touch on differential forms, and only "just barely"
 
They also don't discuss the Inverse Function Theorem much, let alone prove it.
 
@TedShifrin I think it's in an appendix
 
That's kind of sad. Mike says Lee, but he doesn't know about a good mult. calc. book.
God if finding a textbook on the subject is so hard, I think I'd be better off not studying it.
 
8:54 PM
Most math students learn an engineering-style multivariable calculus and then maybe later take a multivariable analysis course.
For the latter, there are a few books (but they all assume you already know single-variable analysis and computational multivariable calculus).
 
AvZ
Where did he go?
@G-man Are you there?
 
Can the same be said for single variable calculus? @TedShifrin
 
Loads of books for single variable calculus out there @infinitesimal
 
Multivariable is way more subtle, however, skull.
 
True.
 
8:58 PM
@AvZ I was waiting here, you were supposed to click on the link.
 
No, @Balarka, not that teach you theory/analysis along with computational stuff.
Apostol and Spivak are the only ones, really.
 
I studied from Piskunov, and it wasn't bad.
 
Apostol's multivariable is a good start, but he, too, doesn't do the level that my book and Hubbard/Hubbard do.
Well, I don't know Russian and Chinese books, for example.
 
Here's one thing: with a single variable, differentiation and integration are "pseudo-inverses". When you have a function $f: \Bbb R^n \to \Bbb R$ some of that symmetry is lost. The closet you get to "recovering it" is something like Stokes' Theorem.
 

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