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00:00 - 21:0021:00 - 00:00

00:00
Can the spheres intersect or are they tangent when you say "touch"?
Tangent. No intersection
@MikeMiller I was hoping there's a sphere packing proof of uniformization in high dim maybe
If I touch you, is my hand tangent to you or am I ripping out your heart?
13
Q: Squaring a square and discrete Ricci flow

Joseph O'RourkeIs this a theorem? Every $3$-connected planar graph $G$ may be represented as a tiling of a square by squares, one square per node of $G$, with nodes connected in $G$ corresponding to tangent squares. I ask because the cited AMS Notices paper1 suggests that this might be a theorem, offering ...

Ah but the spheres can be of different sizes?
Yeah
@Thorgott WTF
00:01
(because otherwise any graph with a vertex of valency bigger than the kissing number is an issue)
It's still an issue :)
@Balarka I'm pointing out that colloquially, touching should obviously mean tangency
LOL oh
Ok I can't stop laughing now
I'm not at all verbalizing my violent anti-set theory fantasies
@MikeMiller That's such an interesting question
The graph is realizable by a circle packing (Andreev's theorem) so I was thinking of slowly inflating those circles to be squares
00:05
@BalarkaSen is it?
@Alessandro Take a sphere in the configuration of smallest radius $r$. Then a bunch of spheres of radius $\geq r$ is surrounding this guy of radius $r$; there can be at most kissing number many such guys, right?
Oh ok
So the complete graph on more vertices than the kissing number can't be done
Yeah, but in fact I claim $K_6$ is impossible.
(I'm just making sure that the smallest sphere has a lot of nbhs whatever the smallest is)
@BalarkaSen Is that sharp? Is K_5 possible?
Tetrahedral packing
00:09
Isn't that K_4?
Oh, I mean, put a sphere at the center of the tetrahedron
Small guy
Can it be done so that it touches the other 4? I guess so
Yeah you have a lot of space in the inside
My intuition for 3D stuff is really poor and my drawings are possibly even worse
Of course, the tetrahedron has a point in the center with equal distance to the vertices and you're putting the spheres at the vertices
00:10
Yeah I convinced myself it has to be possible by symmetry
By symmetry the point on each sphere closest to the center is the same distance to the center for each sphere
@MikeMiller OF COURSE that paper is by Oded Schramm
This guy is a massive legend
This guy is so smart. Holy shit
How
I'm just going to read all his papers during the winter.
This is what I need to read.
The man described himself as a circle packer, because that's literally what he did in his PhD thesis
Two Fields medalists won the Fields medal because of tools developed by a circle packer
Only $280 for Volume I alone.
Apparently i can download the book because for some reason i have university access without being in the campus
Apparently it's free in separate pdfs
and when I say apparently
I mean I just clicked and they're all available
Is that strange for a Springer book?
00:24
@TedShifrin I'm sure the Russian online bookstore will have a copy at an affordable price
10
Also you're getting ripped off, it shows 180€ (around 220$ to me)
Oh no, my bad, I was looking at the ebook
00:39
0
Q: Subsets $A$ of $\Bbb{Z}$ such that $xy \in A \implies x \in A, $ or $y \in A$. Primality of arb. subsets.

CommutativeAlgebraStudentIf $$ A \subset \Bbb{Z} $$ is such that $xy \in A \implies x \in A, $ or $y \in A$. Then $A$ is either a prime ideal or ? Can we describe all "prime subsets" of $\Bbb{Z}$ that aren't prime ideals in one fell swoop? It's not just a set closed under taking divisors, though those are counted, and s...

00:59
@TedShifrin looked up Gronwall's inequality, its very nice
01:36
@JoeShmo Yup. You can use this to prove uniqueness of solutions to systems of linear differential equations (of any order). :P
I missed the pun
So did I. What pun?
I'm lightning fast
but I thought my solution was cute
but it's fluke-y.
@TedShifrin I wish I had gotten people to do problems computing areas of regions like they were planimeters.
Oh yeah? Planimeters are complicated!
01:42
The integral isn't, though
I just mean one can give problems of the form "compute the area of this region" in terms of integrating a specific vector field over the boundary curve, which a planimeter is encoding mechanically
Maybe I'm not understanding your point.
I wish I had thought to have them do problems computing that integral and then point out that one can do this mechanically, thus giving planimeters.
Oh, no, planimeters are more complicated than $A = \frac12\oint_C -y\,dx+x\,dy$.
I'm really making a fool of myself today
Although I thought that would be it when I started to figure it out. But it is Green's Theorem with a pretty tricky pullback.
That's one exercise in my book I don't think more than one student (of mine) has ever done.
01:45
oh haha I am not understanding the :P at the end of that sentence
Your challenge, you mean, @JoeShmo? Just giving you a challenge with my tongue stuck out.
ohhh
I'm not doing challenges outside of harmonic analysis until this semester is over
btw, I got problems in analysis by gelbaum, recommend?
I don't actually know that. I had his Counterexamples in Analysis book.
his other book is really famous
yeah
@AlessandroCodenotti F
logicians had it coming for being such jackass know-it-alls
at least category theory nerds now occupy that position
ah nice didnt even read thorgott's subsequent comments
case in point
@AlessandroCodenotti mood
@TedShifrin btw, thanks for making the connection to thorgott's solution to the problem; the proof of gronwall, and the inequality itself, were never insightful to me before
ah no, the intended solution is the MVT
 
1 hour later…
03:22
What are the integer solutions of $n!-1=m^2$?
Are they just $n=0,1$?
so it has the potential to be really hard
I know that $n!+1=m^2$ is unsolved but I couldn't find any information about $n!-1=m^2$
That made me wonder if it is trivial
oh
consider mod 4
I'm pretty new to NT so could you explain a little more please
for $n\geq 4$, $n!\equiv 0 \mod 4$ and then you have $m^2\equiv 3$ which is impossible because 3 is not a quadratic residue mod 4
03:36
ah okay I think I understand now
btw if you don't know what a quadratic residue is, it just means that $0^2\equiv 2^2\equiv 0$ and $1^2\equiv 3^2\equiv 1$ so there isn't any number whose square is $3\mod 4$
04:08
Hi chat
05:06
Hi, can anyone say that whether it is worth registering for brilliant.org or not? Would I get a good practise for number Theory/Algebra/Geometry? I am not from a math background.
@roydiptajit it's good for problem solving, olympiads, but would no help much in advanced mathematics.
And yes, if you are not from a mathematical background, it is probably good to start from there, but don't forget to read books
But your profile is telling that you know about algebraic number theory, so why are you saying that you are not from a mathematical background?
05:33
If you have learned algebraic NT, I am 99% sure that you already know the contents of brilliant.org
@TedShifrin is the intention here $\mathrel{\int\!\!\!\!-}_{\frac{1}{\lambda}Q}\ f(\lambda x)\ dx = \mathrel{\int\!\!\!\!-}_{Q}\ f(x)\ dx$? if you expand out the average it's not true.
05:51
@JoeShmo what is the bar? Certainly there's a $\lambda$ missing from change of variables?
@LeonhardEuler I have just started learning algebraic number theory. I am not from a mathematical background and as I am really interested in solving problems, I opted research in computational number theory, and my research involves depth into algebraic number theory. But as I am not from a mathematical background I was thinking, it is perhaps better to solve these problems in free time as the people in this field are really familiar with these staff
bar is an average over the qube
Average over what?
$\mathrel{\int\!\!\!\!-}_{Q} f(x) dx= \frac{1}{\mu(Q)} \int_Q f(x) dx$
Crazy notation.
What dimension is $Q$?
05:55
@roydiptajit do you know calculus?
$Q \subset \mathbb{R}^n$
Oh, so the volume scaling gives you the COV factor. It's right.
Just one final tip: first see the list of courses in brilliant, decide which courses you know, a then subscribe if you haven't learned their content
ohh.. stoopid stoopid
Me or you?
06:01
who do you think
The president.
:-)... me
I really need to learn how to change variables....
You can watch my video :)
I scaled the domain and the argument of $f$.. instead of changing vars
Well, however you think of it, the Jacobian has to be there.
06:04
yurp
@LeonhardEuler Yes just the basics, never prepared for olympiad or other math exams which uses advanced syllabus
its the pesky jacobian all over again
Differential forms do it for you automatically — that's (one reason) why they're so powerful.
youre like a poster child for differential forms
one day I'll learn them, promise
Of course I am.
06:06
and maybe I'll be able to change variables then
@LeonhardEuler Actually I was thinking that whether my little problem solving background will cause any trouble for me afterwards
I have to be true to my heritage!
06:34
@roydiptajit you should probably try it
and @roydiptajit, learning from books is a million times better than learning from brilliant
07:00
@LeonhardEuler Yes actually I follow I lot of books, I was just asking for suggestion whether I should do it or not. I was worried if these lack of practise would cause me any trouble. If you say no then its ok, I do not want to waste my money, if it is of no use :-)
@roydiptajit some better alternatives to brilliant are books like IMO compendium, art and craft of problem solving, etc.
they are a lot better than brilliant.org
for anyone here who wants to truly master in NT, see what I have mentioned here:

 Analytic number theory

For people interested in analytic number theory, a field of ma...
07:46
Okay thanks
@LeonhardEuler What does your images mean?
they are fractals
I post them here daily
08:32
If $X$ is contractible, then $[X,Y]$ is not necessarily consists of a single element?
$X,Y$ are topological spaces and $[X,Y]$ denote the set of homotopy classes of maps of $X$ to $Y$
I don't assume $Y$ is path connected
123
123
Hi All..
08:45
Hello!!
To show that $1<\sqrt{2}<2$ do we use the fact that $1<2<4$ or how do we get that inequality?
First prove $\sqrt{2}<2$
A good way would be by contradiction
So we suppose that $\sqrt{2}\geq 2$.Then do we square the inequality? Or how do we continue? @LeonhardEuler
squaring both sides of an inequality will be valid as long as both sides are non-negative.
Both sides are positive, so there is no harm in squaring
by squaring, we get $2\ge4$
But why do you even want to prove this obvious thing?
It is a part of an exercise. After that do we have to show that $1<\sqrt{2}$ again by contradiction? @LeonhardEuler
you can square both sides, so contradiction is not necessary
I just added contradiction unnecessarily
is it a problem in real analysis?
08:57
Ah so for sides we can it like that?
It holds that $1<2<4$ and taking the root we get $1<\sqrt{2}<2$.
@LeonhardEuler
@LeonhardEuler Yes
yes we can take square roots
Ok! Thank you :-) @LeonhardEuler
np
Let $N(x)$ denote the number of composite $n\le x$ for which $\varphi(n)|n-1$
How can we prove that $$N(x)=O(\sqrt{x}(\log x)^{3/4})?$$
@LeonhardEuler Ohh how did you create these?
using a software called xaoS
also ultra fractal
that theorem looks a bit hard to prove...
any idea?
 
2 hours later…
10:50
the name of this post sounds funny to me:
0
Q: Showing that a family is not normal

Kabouter9Suppose $f : \mathbb{D}\setminus \{0\} \rightarrow \mathbb{C} $ is analytic and $z=0$ is an essential singularity of $f$. Show that the family $\{f_n\} $ defined by $$ f_n(z) = f \left( \frac{z}{2^n} \right), \quad z \in \mathbb{D}\setminus \{0\} $$ is not normal in $\mathbb{D}\setminus \{0\}$. M...

11:04
[tag: dysfunctional~family]
11:16
exceptional level of rigor in this answer:
9
A: Oscillatory integral with absolute value

Alex RavskyProposition. Let $f:[0,1]\to\Bbb R$ be a continuously differentiable function such that $f’(x)\ne 0$ for each $x\in [0,1]$. Then $\lim_{n\rightarrow \infty} \int_0^1 |\cos(nf(x))|dx=\tfrac {2}\pi.$ Proof. Since $f’$ is a continuous function on a compact set $[0,1]$, it is uniformly continuous and...

12:14
How is Daniel Fischer able to find $\epsilon, \delta > 0$ with the prescribed properties?
12:37
Whoops...never posted the link...
2
Q: Meromorphic Function is Rational

Joshua BunceI'm asking for clarity on the method given above. If there is a duplicate post, it is only duplicate if it addresses this. Thx! Let $f(z)$ be a meromorphic function on the complex plane, and suppose there is an integer $m$ such that $f^{-1}(w)$ has at most $m$ points for all $w \in \mathbb{C}$. ...

Again, how is Daniel Fischer able to find $\epsilon, \delta > 0$ with the prescribed properties?
13:07
If $f(z)$ is an invertible, analytic function, is it true that $(f^{-1})'(z) = \frac{1}{f'(z)}$?
If it doesn't vanish at a point, I think so yea
Wait it should be $(f^{-1})'(f(z))$
$1 =(f\circ f^{-1})' = (f^{-1})' \times f'\circ f^{-1}$
13:43
Hello
13:53
Hi All! I'm wondering if anyone can help me with this question I've posted here: stackoverflow.com/questions/65160903/…
I've gotten as far as converting all of my time data to seconds and then finding my mid_day and mid_night time in seconds thanks to spc but I can't quite get there after that. His 4 equations don't quite make sense to me.
Furthermore, If anyone can think of a better way of doing this based on my sunrise and sunset data please let me know!
Is there any easy way to find the normalizer of $H$ where $H=\langle a^2,b^2,aba^{-1},bab^{-1}\rangle<F(a,b)$
Hey is there an easy way to draw graphs (edges and vertices)?
 
1 hour later…
15:16
I dunno why apostol's analytic NT book is saying that "it can be read by high school students". Man, it uses advanced calc and complex analysis
Lol
@LeonhardEuler Clearly, since this book is for forty years ago!
At no point in history has advanced calc and complex analysis been taught in high school.
Source: trust me it's probably true
15:34
@Khallil is right @user91500
@Khallil Apostol says "it can be read by high school students" but don't say all high school students.
Let $x > 0$ but not all $x > 0$
:p
@Khallil Also it depends on high school definition. I learned advanced calculus when I was a high school student.
 
1 hour later…
17:06
@Khallil *in the US
When I think of advanced calculus, I think of a level of rigour from elementary real analysis (and anything more involved). Do you know of any countries where stuff like that is taught before university/college, @user2103480?
Romania, I think
That's interesting! I have a friend who studied biology at university and she said she'd seen the stuff I was doing at the time (introductory functional analysis). I thought they were joking :o
Russia and Hungary maybe also have some stuff along those lines in advanced courses. A former teacher of mine told me that 30 years ago, they taught vector spaces in german high school
in the advanced classes, near the end of school at least
"Abstract" vector spaces I mean, not just vectors in R^n
17:49
It must be tough to try and develop a curriculum for schools.
18:31
Any such claim is not meant to be literal. If I say my book can be read by someone who has taken a course in multivariable calculus, does that mean that someone who learned nothing in said course (or even got a B, say, or even an A) is guaranteed to understand mine? I think not. After all, some teachers give A's freely and cover very little material and the students have little comprehension. It's hopeless to make a universal statement.
That feeling when you hit enter too early on a stack answer and then you have to scramble to edit the rest of your answer in while answering questions taking apart your incomplete answer.
Well, I just closed a question and the OP was irate that I didn't read his complete question carefully. He was right. He had a long post about differential geometry (of which there are many duplicates), but his question was just why if $v=\sum_{i=1}^3 c_i e_i$ and $e_i$ is an orthonormal basis, then $\|v\|^2 = \sum c_i^2$. Seriously. Talk about not having learned anything in prerequisite courses.
I guess I would not try to answer all the questions. I would say something like. "I know. I'm editing right now." and leave it at that until you're done.
trying to learn differential geometry without a solid understanding of linear algebra seems like a bad idea
Undergrad, Lukas. Undergrad.
But you need some basics from linear algebra (like what an orthonormal basis is) and basics from multivariable calculus (like directional derivative and Green's Theorem).
oh yeah right, I guess if you do curves and surfaces in R^3 you don't need that much
18:40
I actually have a short appendix in my notes summarizing the basics needed.
I always forget more elementary differential geometry exists since the intro course here at Heidelberg just throws manifolds, forms and Riemannian metrics around from the beginning
Same thing at my old uni, @LukasHeger.
Klingenberg wrote a lovely little curves and surfaces book 50 years ago. I'm sure he taught it numerous times.
@LukasHeger trying to learn differential geometry without a solid understanding of linear algebra seems like a bad idea*
@Alessandro lol
18:42
I think throwing super-sophisticated stuff at students who have no background or intuition is a huge mistake. U Chicago does the same thing with their "honors multivariable" course that skips most of what the title is and does functional analysis with freshmen/sophomores. I think every math student should have a solid foundation in multivariable calc/analysis.
smacks demonic Alessandro hard
I actually think the teaching of mathematics across the board is in pretty bad shape.
functional analysis is considered a standard sophomore course here
@LukasHeger you can say "I forget more elementary any course exists since the intro course here at Heidelberg just throws really hard stuff around from the beginning" and be fairly accurate
@Edward lol
Our multivariable calc/analysis course was weird, we did forms and Daniell integration from the beginning
It's a corollary of the Bourbaki-ing of mathematics, where one makes everything as formal as possible and students never learn to calculate or to work with examples.
I don't mind doing forms for good math majors, but you still have to make connections with the classical notation/understanding.
That is precisely how I learned the Frechet derivative and differential forms. Thanks, Bourbaki Boys.
18:45
Of course, I love forms (JoeShmo called me the poster boy for them :P).
I think students who learn from my book do better than that, @Khallil.
our first definition of differentiable functions was for Banach spaces...
@LukasHeger When do you do measure theory and topology?
but we did show that it agrees with the classical difference quotient definition
@LukasHeger lol
@Alessandro the first three semesters are Analysis 1-3 which include intros to topology and measure theory. Typically topology in Analysis 1 or 2 and measure theory in analysis 3
18:47
Lukas, I admit that I like to do the proof of the Inverse Function Theorem that works verbatim in Banach spaces. The "compactness" proof in $\Bbb R^n$ that Spivak and Munkres have is just not natural to me.
The inductive proof is the wrong damn proof
It has no intuitive content
Inductive? That's change of variables.
then functional analysis is considered as a fourth semester course typically
Yeah, I hate that proof too.
You agree the standard non-contraction principle proof is inductive, right?
It's a trick to my eye
18:48
Oh, I wasn't talking about that proof.
We had a two page proof of the Implicit Function Theorem on Banach Spaces in an old course.
Literally skipped those two pages and never looked back.
I was talking about the proof that proves openness by looking at distance to the image of a sphere and using the maximum value theorem.
I don't remember this, I doubt I like it
@EdwardEvans I agree, we even defined Noetherian rings and modules in freshman LA lol
lmao
18:49
Yeah, I also hate the inductive proof of change of variables, @MikeM, although the honest proof without Lebesgue is torturous. Even having been careful, I ended up with a small mistake in my 4-page proof in my book.
what kinda mutant LA course is that
That's one unique undergraduate education.
@Lukas you had Böckle right?
Germans
18:50
this is why I dropped AlgGeo
we literally had exercises proving that the three standard definitions of Noetherian rings are equivalent and we had to prove that f.g. modules over a Noetherian ring are Noetherian
LOL @MikeM
Well, the US is sort of the polar opposite. Here at good universities a student can get a math degree having learned very little mathematics. (Of course, I am sure there are some in Germany who learn very little as well.)
@Edward I really think you should take AlgGeo at some point, though, it's foundational for a lot of NT
and there's no reason to fear Böckle, he's great, I did my LA lectures, the group cohomology seminar, the seminar on algebraic groups, the seminar on local Langlands for GL(2) and two years worth of ANT by him
yeah I plan to, it probably would've been easier than p-adic Hodge theory
I think so, too
18:53
and probably necessary to understand the real meaning of the stuff we're doing
but eh
But your taste, Lukas, is perhaps non-standard.
I think Böckle has some things in common with you as teacher @Ted, he likes to challege the students, but he's always fair
@TedShifrin indeed
now the question is whether or not the German who can tell me what a prismatic ring is but not an example has learned any mathematics
Lukas, thanks for the compliment, and I wasn't criticizing his teaching. I was saying that your taste/ability is not necessarily standard.
oh that's certainly true
18:56
hodgepodge theory
even our advanced courses like ANT always had computation and examples
perhaps our LA courses had less computation than some courses which don't do proofs, but there was still some amount
Linear algebra is tricky. It's too easy to make too much busy-work, mindless computation. But concrete problems are important.
EM4
EM4
hello guys.
I'm hoping to include a lot of perhaps optional material about algorithmic linear algebra next sem
Yes, an applied linear algebra course should definitely have that (without option, I would think).
Hi EM4.
19:04
I've never had or seen one that does
Really?
Perhaps tragically, no
Well, maybe I don't understand what you mean by algorithmic.
Oh. Discussion of numerically efficient algorithms for computations. Strassen for fast matrix multiplication, inverting matrices efficiently.
We don't do that in LA, but do it in numerical analysis (which everyone has to take)
19:06
I've taken a course where one could easily leave thinking the best way to invert a matrix is to apply Cramer's rule
Yeah, numerical algorithms. OK, yeah. And the cute repeated application of QR to find highest eigenvalue, eigenvector, etc.
didn't they teach you how to invert a matrix using Gaussian elimination?
we learned that even in our proofs-heavy LA course
@MikeMiller I repeatedly say that Cramer's rule is useful for $2\times 2$ or $3\times 3$ and theoretical consequences. It gives the easiest proof of the classical adjoint inverse formula.
right
I'm only talking about my experience taking such courses --- not what one should do
I dislike plenty of standard textbooks for faults like this, where it feels like they're not teaching to anybody in particular
Strang definitely discusses numerical aspects in his more advanced book, a little bit in his easiest book.
19:08
Not suitable for math majors and also not suitable for applied people
Wilkinson is a classic text I looked at occasionally, but too advanced, for cool numerical things.
I'll jot that down
The Algebraic Eigenvalue Problem
I'd like to give a reasonably standard course with optional material for those who are interested in either the more abstract side of things or the more numerical side of things
Both are reasonably accessible from the get-go and reasonably interesting
But either you expect students to write proofs or you don't :P
19:11
Sure, I don't, because they haven't been trained to
And in this dept it's not the linalg course's job to be able to
we learned how do proofs in our LA course and we did module theory up to STFGMPID
That's not an acceptable abbreviation
OK ... in our department the usual linear algebra (now almost dead) has the intro to proofs course as a prereq, but the applied course of course does not.
We only have one (lower-div applied)
Gotcha.
19:12
I gotta get back to grading project drafts
Thanks for the tips
Have fun!
I'll try
I should add that our LA courses are only taken my maths and physics majors, for example chemists or biologists have courses like "math for scientists"
Statistics actually has a lot of geometric linear algebra hiding in it. They just don't bother to elucidate it.
In hindsight, having a course on logic and how to prove things is very useful but at the time when you're lost in the sauce, time passes very quickly and you still don't really grasp it all until the end of the first year.
Like contrapositives and contradiction at face value is understandable but you don't really feel it until you start doing some real analysis or group theory.
Or at least that was my experience!
19:16
We don't have such "intro to proofs" courses, you just learn how to do proofs in linear algebra and real analysis
I'm not sure what an intro to proofs course even is
like, how do you fill more than one lecture worth of content with that
Getting students used to writing/reading language and interpreting it. Basic logic, sets, induction, proof techniques, functions, preimages, maybe a little bit of division algorithm.
We did a bit of basic number theory, induction, introduced number systems, sets, functions, relations, truth tables, graphs, some diagonal arguments and a little discussion on types of infinities.
we did all that in ~2 weeks in LA and real analysis
@Thor: The average math major in the US will never get to your level. When I was a student, it was assumed we were all smart enough to learn this in our abstract algebra and analysis courses. But then education degraded and students just couldn't do anything.
19:19
Some of it was recap, a lot of it was just formalising all the things we took for granted pre-uni.
Part of the goal was to save teachers/students from having to see the same introductory stuff — too fast for most students — in their algebra and analysis courses.
@LukasHeger Yea it was a very short course for us and was pretty much designed to get everybody up to speed.
we do have something we call "Vorkurs" which I guess translates to preliminary course, it's an optional thing done by students which introduce basic logic, sets, functions before the actual first semester starts. But that's just 1 week
I taught it a couple of times. I had very few A's in there, but several of the students went on with me to other courses.
Remember that the US high school education system is very generalized. In Europe, don't you all have to pick math/science vs. social science vs. humanities by the middle of high school and get a very specialized high school education? I know it's that way in France.
everyone who is in the university-track high school does calculus and linear algebra in high school in Germany
I can't speak for other countries, there are many different systems
19:23
Yes, well, that's 100% different from the US.
And the ones who do AP calculus and often linear algebra in high school get mostly crappy courses here.
There's a lot more respect for high school teachers in Europe than there is in the US, so you have much more highly qualified teachers.
And now that we've been Trompified, things are going to be worse here.
hi @TedShifrin
you got a new president now :)
Anyhow, enough depressing talk.
how well you do in high school calculus and linear algebra can make a big impact if you get good grades which can be important even if you want to study something that doesn't involve much math at all
Who will be totally powerless unless the two GA Senate run-offs go to the Democrats, @Karim. I'm sending lots of money every week.
Demailly book is amazing.
19:25
A lot of stuff in it, yeah. I don't know it well, but I downloaded it years ago.
amazing book I am finishing first chapter a lot of good stuff in it a lot of my PhD thesis will be based on
twisted currents
twisted version of currents
You make it sound too fancy. If you can do forms with values in a vector bundle, you can do currents with values in a vector bundle :)
yea right
I will do my thesis on twisted hodge conjecture on surfaces by twisted I mean sections are covered by flat vector bundles
@TedShifrin I spent most of my money on books
spend *
I used to do that when I was in school, too, @Karim. But times are different.
when I make money I want to donate to organizations like khan academy and governments that really contribute to the world
@MikeMiller is making all the money now as postdoc :P
19:38
Only slightly less penniless than a graduate student.
Food can be expensive
Not to mention rent.
@TedShifrin is this the book you were talking about earlier from Klingenberg on curves and surfaces?
Thanks! I'm gonna give it a read at some point
19:46
@TedShifrin Yeah, it's actually a good strategy nowadays to stay with a parent or someone else who owns the place you would be living. It removes that burden.
My recollection is that it's quite carefully written.
20:28
@LukasHeger our LA II prof went through some, to us, really obscure proof of jordan normal forms via modules
People do like to do that
Diff Geo was along the same lines as you describe, although I didn't take it after the manifolds & differential forms part in analysis 3 was enough for me.

The definition of the derivative was the simple one in analysis 1 - but in analysis 2 we were also hit with the banach space definition lol
@MikeMiller yeh the prof works in representation theory so it was probably the natural approach. To us, though, utterly incomprehensible
No I agree with you
I find the module-theoretic proof to be much more lucid than the usual inductive ones
algebra brain
20:41
@Thor: I actually agree with you. Although they're not exactly too constructive. I learned this from Artin in my algebra course sophomore year and loved it.
But differential forms were still the worst of all. Desperately, I tried to find any reason for why the things are defined as they are. I later learnt that there is indeed an abstract characterisation of the wedge product, as for the determinant, as an example
I think you can get something constructive when unwinding the details in the abstract proof, but it's admittedly much more cumbersome
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