« first day (1508 days earlier)      last day (3506 days later) » 
01:00 - 19:0019:00 - 00:00

7:04 PM
@nablablah Hi Bart. How is school?
 
Hi @JasperLoy
It sucks
 
You did very well last term.
 
The classes were at least interesting last term
My analysis class is not a real analysis course..it is a joke and I don't understand why it's a requirement for the math major when there is a graduate real analysis course available for students to take
 
@nablablah What are you studying in that class?
 
Absolutely nothing
He talks about his family for about half the class
Then some other nonsense
 
7:09 PM
OMG.
It's OK to talk about these, but not too much.
 
He spent an entire 2 lectures (~2.5 hours) proving the equality of ordered pairs
 
Most people can do it in their head in less than a few minutes
 
Huy
I can't.
 
For the exams, he wants us to memorize his definitions/theorems word for word and he gives no partial credit so if you make a mistake with an article such as "the" or "a" you get 0 points for the entire problem
 
7:11 PM
@nablablah You mean that (a,b)=(c,d) iff a=c and b=d?
 
Yes
 
That should only take 10 min at most.
 
But anyway, the point is that 3 weeks have passed and I haven't learned a thing about real analysis
 
Huy
@TedShifrin: Projective geometry is part of the standard curriculum.
 
@nablablah Word for word is unreasonable.
@Huy How about affine geometry?
 
Huy
7:13 PM
@WillHunting: I don't think I know enough about it to teach it and find interesting examples for high school pupils.
 
The time now is pi am.
 
Huy
21:14 over here.
 
pi pm here
 
We are on opposite sides of the globe, lol.
@nablablah That proof belongs more to a set theory class than a real analysis one.
 
7:17 PM
Oh well
This is my punishment for not doing well in high school
 
I have officially retired from SE, but I will come here to chat.
 
@JasperLoy you like Willard better than Munkres or Mendelson?
 
Certainly. If you were to ask me to recommend one book covering general topology and nothing else, it is Willard.
 
Cool
 
It is also a cheap Dover paperback.
 
7:23 PM
I don't like the Dover paper
They feel like the brown paper tissues in the bathroom
 
I hope your mum no longer throws away your books. Otherwise, she needs to be locked up.
 
I don't live with her anymore
 
I think I will sleep at 6 am, so another 2.5 hours.
 
You need time to get into bed and fall asleep so make that 2.4 hours or something
 
I will look for you in the US when I go to grad school there.
I drink lots of coffee these days.
Oh @nablablah you must watch the movie "If I stay", best movie ever.
 
7:30 PM
Does it have math in it
 
Nope, but it made me cry a lot.
 
Huy
Forrest Gump did the same to me.
 
@Huy I did not like that movie somehow.
 
@JasperLoy when do you hear back from grad schools
 
@nablablah I have not even applied, lol. My plan is to enter in Sep 2017.
 
7:32 PM
Oh
 
Maybe we can be classmates, lol.
 
I think I will have finished my courses by fall 2017
 
Aha, so grad school in Sep 2017 for you too.
 
No, grad school next year
 
Oh, lol.
 
7:34 PM
I will tell you which school I get into if I get accepted into any
 
But it might never happen for me. I need to get well first.
If I did not go mad, I would be a prof by now.
 
I read a play called "Proof" which is about some mathematicians
 
I saw the movie Proof.
 
I think there is a movie based on the play
 
@nablablah Have you found a gf?
 
7:36 PM
I might have to act out a scene for my acting class
@JasperLoy I haven't spoken to a girl since I came to this school yet
 
OMG
@nablablah I am 33 and never had a gf, lol.
 
That was the age Jesus Christ died
 
That is also the age my teacher died.
 
Which teacher
 
My elementary school teacher. She went for brain surgery and it failed.
 
7:41 PM
Baw
I had a classmate who got brain surgery for a tumor
 
She was a strong Christian.
 
I am pretty weak
 
I am an ex-Christian. I am also a semi-Buddhist.
 
Should I convert to Christianity
 
7:44 PM
@nablablah You should think about it for yourself.
 
But if I prefer others to tell me what to think, should I become a Christian
 
Regarding the image above, the three conditions at the beginning of the passage are all separate, right?
 
@nablablah No, letting others decide for you is never right.
@Khallil Yes, 3 different things: apples and bananas and cherries.
 
Cool! Thanks, @Will.
 
I only like bananas because they don't have inedible seeds like apples and cherries
Except you can't eat the skin of a banana like you can with apples and cherries, I guess..
But the skin is convenient anyway
So I still prefer bananas from those 3
 
7:47 PM
@Khallil It's saying that it doesn't change if apples, it doesn't change if bananas, and it doesn't change if cherries. Make sure you understand.
 
Yep. Got it.
 
@nablablah My favourite fruit is banana.
 
Why @JasperLoy
 
It's always sweet, unlike most other fruits, and it is cheap and nutritious.
 
Even un-ripe bananas?
 
7:50 PM
Of course, they need to be ripe.
People post questions here whose answers can be easily found in textbooks, lol.
Do they even read books these days?
 
Do mathematicians like literature?
 
$$\int_0^{\pi/2} \log \left(\sin\left( \frac{x}{2} \right) \right) \log\left(\cos\left(\frac{x}{2}\right)\right)\log(\cos(x)) \ dx$$
 
@user96402 What kind of literature?
 
Poems
 
Mathematics is the poetry of logical ideas.
 
8:12 PM
That guy that forgot everything about math should be part of some famous hall of students. :-)
 
Huy
That blackboard is ugly. :(
 
@Chris'ssis That would be a crowded hall.
 
@IceBoy lol :-)
 
:D
 
8:31 PM
@Karl!
 
Ahoy!
 
hello
@Khallil yes, do it
it shouldn't be hard.
consider $(x+y+z)^3$
 
I've got it down to the form below, and I'm going to begin work on manipulating the stuff in parentheses. $$x^3 + y^3 + z^3 = (x+y+z)^3 - 6xyz - 3 \left( xy^2 + xz^2 + yz^2 + x^2y + x^2z + y^2z \right)$$
Yep, already thought of that by extending the two-variable cases, @Balarka. ^_^
 
cool. but the stuff in parenthesis needs trick
note that $xy^2 + x^2y = xy(x + y)$. pair them like that and see what you can do by trickery.
 
Yep, that's what I'm focussing on. I think I've seen something else quite similar before.
Yea, I've already done that. I got something that looks like this $$xy(x+y) + xz(x+z)+ yz(y+z)$$
 
Huy
8:40 PM
@Khallil: What are you trying to do?
 
yes, that is obvious, but what next?
@Huy Newton's identities.
Don't tell him.
 
Don't spoil it for me, @BalarkaSen and @Huy!
 
Huy
@BalarkaSen: Which ones?
 
Thank you, @BalarkaSen.
 
@Huy $x^3 + y^3 + z^3$
in terms of elem. symmetric polys.
 
Huy
8:41 PM
@BalarkaSen: So. Algebra.
 
58 mins ago, by Khallil
user image
 
@Huy yes, just basic algebra.
 
Huy
I see.
 
:-)
3 mins ago, by Khallil
Don't spoil it for me, @BalarkaSen and @Huy!
 
Huy
Don't worry. The only thing I remember from algebra is Lagrange's theorem and some Galois theory.
Oh, and Sylow, of course.
 
8:44 PM
Galois is my favorite.
 
It already seems like a symmetric poly. I tried interchanging $x$ and $y$, $x$ and $z$ and $y$ and $z$. Now, I only need to rearrange it into the necessary form, @Balarka. ^_^
 
Lagrange's theorem? Huh? @Huy
 
Huy
@BalarkaSen: I was blown away from its application.
 
I'll find that trick, no matter what!
 
@Khallil try to snuggle in a $z$ in $xy(x+y)$
 
Huy
8:45 PM
@BalarkaSen: Lagrange's theorem from group theory. Nothing big. Just something I think of when I think of algebra. ^w^
 
@Huy Galois theory? Your are referring to unsolvability of quintics while you are referring to applications right?
 
Huy
@BalarkaSen: For example, yeah.
 
@Huy Ah. I was thinking of Lagrange resolvent, hehe
@Huy what else do you have in mind? the other applications i know of are quite technical (i.e., haven't studied them =P)
 
hmmm, you say so ... $$x^3 + y^3 + z^3 = (x+y+z)^3 - 6xyz - 3 \left( xy^2 + xz^2 + yz^2 + x^2y + x^2z + y^2z \right)$$
 
yes, @Chris'ssis?
 
Huy
8:48 PM
@BalarkaSen: Well, firstly from Galois' theorem not only unsolvability of quintics follows but for $n \geq 5$, iirc.
 
yep, that's another. right.
 
I'll try to apply it here for instance ... (in a new proof)
(of course, I know this identity since I was 10 or so)
 
Huy
@BalarkaSen: A lot are geometrical applications. For example, as far as I remember, you can prove in one sentence that it is impossible to trisect an angle using compass and straightedge.
 
eh, it's a highschool identity alright.
but how're you going to apply it, @Chris'ssis?
 
I think I have it, @BalarkaSen. Let me write it up.
 
8:50 PM
@Huy That's.... not Galois theory.
cool @Khallil
 
@BalarkaSen I think I set things like that $x=\log(1-t) , y=\log(t), z=\log(1+t)$
 
Huy
@BalarkaSen: You can use Galois theory to prove it a lot quicker?
 
@Huy Heh?
 
Huy
@BalarkaSen: Heh?
 
It's sufficient to know a bit of field theory to prove that geometrical impossibility, @Huy
 
Huy
8:51 PM
Doesn't mean you can't apply Galois theory to prove it in a lot faster way?
A famous application of Liouville is the fundamental theorem of algebra.
 
I don't know of such proof.
 
Huy
But you can prove it with only calculus 1.
 
@Huy FTA with calculus 1?!?!
 
Huy
That's really not my fault.
 
@BalarkaSen $$ \begin{aligned} \alpha = x+y+z \implies xy(x+y) + xz(x+z) + yz(y+z) & = xy(\alpha - z) + xz(\alpha - y) + yz(\alpha - x) \\ & = -3xyz + \alpha(xy+xz+yz) \\ & = -3xyz + (xy+xz+yz)(x+y+z) \end{aligned} $$
 
8:52 PM
@Khallil Do you have a uniqueness proof of your solution yet? :P
 
So, @Huy, what's the proof using Galois?
@Khallil yep
and you're done.
 
Sorry, I have no idea of what you mean, @Karl!
Nice, @BalarkaSen!
 
@Khallil There's no other way of writing x^3+y^3+z^3 as a polynomial in the elem. sym. polys.
 
I took a leaf from that other question I posted with all the $\alpha$s, $\beta$s and $\gamma$s as the roots of a cubic, @BalarkaSen. ^_^
 
Yes there is @Karl
 
8:54 PM
There isn't, @Karl?
 
Just add a $0$ at the tail.
 
lol
"write" is a bad mathematical term
 
yep
@Khallil As you move forward, you'll see a cool theorem stating that all symmetric polynomials can be expressible in terms of elem. sym. polys.
 
@KarlKronenfeld would you prefer "express"?
 
8:56 PM
I think I've already seen the end result of the theorem, but I haven't seen the proof, @BalarkaSen. It's by Newton, right?
 
You can prove it by induction on the degree of your given poly, which also yields an algorithm for constructing the poly of elem. sym. polys
 
OK, back to @Huy. The impossibility of that construction essentially reduces to proving that a root of an irred cubic can't be inside a quadratic (degree $2^k$) extension. I am not sure how you'd accomplish it by Galois : it's just obvious from basic theory of field extensions.
@Khallil I can't possibly know the authors of every theorem I've read!
 
Huy
@BalarkaSen: I haven't done algebra for over a year so I don't really remember everything, but I do recall having proven the impossibilities of those constructions twice, once just with theory of field extensions and then another time - a lot simpler - with Galois.
 
Very true! I can hardly remember the theorems I've seen, @BalarkaSen!
 
@Huy That must be interesting.
You're familiar, @Karl?
 
8:59 PM
@BalarkaSen with what?
 
Oh wait you're not referring to monodromies are you @Huy?
 
Ah, you're convo with huy
 
@KarlKronenfeld a galois-theoretic proof of impossibility of trisection of angle?
 
Huy
@BalarkaSen: Not sure.
 
@Karl wat
 
Huy
9:01 PM
I'm a bit too tired to read this. :D
@BalarkaSen: And yes, I'm 98% sure we proved the fundamental theorem of algebra in calculus 1.
 
!!!111!
 
By the way, do you sing while computing some math stuff? I'm singing right now, especially because of discovering some awesome stuff.
 
@Chris'ssis Noise distracts.
So no.
 
@BalarkaSen :D
 
@Karl Did you find anything of interest about prime twins?
 
9:11 PM
@Chris'ssis singing or humming?
 
6
Q: Closed-form of $\displaystyle\sum_{n=1}^\infty\frac{(-1)^{n+1}}{n}\Psi_3(n+1)$

Anastasiya-RomanovaDoes the following series have a closed-form \begin{equation} \sum_{n=1}^\infty\frac{(-1)^{n+1}}{n}\Psi_3(n+1) \end{equation} where $\Psi_3(x)$ is the polygamma function of order 3. Here is my attempt. Using equation (11) from Mathworld Wolfram: \begin{equation} \Psi_n(z)=(-1)^{n+1} n!\l...

Yeah, it's possible ...
@IceBoy singing :-)
 
icic
:-)
 
I usually watch TV programs or anime whilst working, @Chris'ssis. That's probably why I'm so unproductive. =P
 
throws tables
 
:-)))
@BalarkaSen How many tables did you throw so far? :-)
 
9:15 PM
Lots =D
 
Good! :D
 
I missed it @Khallil :(
 
runs and hides from @Chris'ssis
 
Don't worry, @IceBoy. I got the answer to my question right after I posted it. ^_^
 
9:20 PM
icic
:-)
 
@Khallil Have you seen Gustavo lately?
 
I saw Gustavo yesterday, I think, @BalarkaSen.
 
Oh?
Well I guess I had wrong timings.
 
Actually, the last time we spoke was on Monday.
Sorry. ^_^"
 
I was right
Well, too bad, since I had a DBZ theory to discuss with him
 
Deriving that result took me way longer than most people on my first try, @Daniel!
 
There's a simple combinatorial proof. Should I add it? ;)
 
DBZ as in Dragonball Z, @BalarkaSen?
 
Yes, @Khallil.
 
@Khallil How many people's time did you measure?
 
9:33 PM
No comment.
^_^"
 
why not?
 
I don't have a clever comeback!
 
be honest
 
Last time Gustavo and me were discussing theories about Goku being a powerful than most of the Sayians (except possibly Broly), @Khallil
@IceBoy I have measured at least one persons time.
 
It took me a few months to understand it, @IceBoy.
^_^"
 
9:36 PM
getting there is half the fun :-)
 
Half the fun and 100% of the torture!
 
one man's torture is half another man's fun
 
stabs @IceBoy on the face haves fun
I know
I make up words on the way =p
 
np
 
Great snakes it's thundering hard in here.
With massive rain.
 
9:45 PM
I am going to sleep in 15 min.
 
see ya later pal
 
17
A: Closed form for ${\large\int}_0^1\frac{\ln(1-x)\,\ln(1+x)\,\ln(1+2x)}{1+2x}dx$

Julian RosenThe value of $I$ is a $\mathbb{Q}$-linear combination of values of the multiple polylogarithm at rational arguments. I'll explain how to compute this. Expanding each logarithm in the integrand as an integral, multiplying out, and dividing into regions, and making the substitution $x\leftrightarr...

Just WAAAAAT
Beyli coverings in an integral problem? Tate motives? Vector Bundles!
O_______O
silently leaves chat I have much to learn.
 
later
my friend
 
What's the use of the geometric mean?
I see why the arithmetic mean has useful applications (for finding the mean of a set of values), but I can't see where the geometric mean comes in.
 
I find it interesting that most mathematical software cant solve $$\int \frac{\sin x}{\sqrt{1-x^2}}+\arcsin x\cos x\,\mathrm dx$$
 
10:03 PM
Is it possible to find an elementary antiderivative, @Darksonn?
 
yes
 
@Khallil Take logs.
 
The solution is $\sin x\arcsin x$
 
:O
Thank you, @BalarkaSen. I can't believe I didn't see that!
 
It's just arithmetic mean for logged variables, @Khallil
In that way, AM-GM becomes the indicator of concavity of $\log$. (Jensen's ineq)
Right you are
@IceBoy Calculi and concavity sure makes it painful.
 
10:05 PM
What or who is Calculi, @BalarkaSen?
 
Calculus $\mapsto$ Calculi. Google it.
 
I tried Googling it, but it was to no avail, @BalarkaSen.
Oh, it's the plural.
 
10:25 PM
Oh.
You and your hipster dental jokes, @Balarka.
 
throws a table at @Khallil
 
May I get some attention to this question (math.stackexchange.com/questions/937062/…) from moderators? I flagged it for migration to Cross Validated but I haven't received any response.
 
10:56 PM
Wakes up from the concussion caused by being bludgeoned by @Balarka's table
 
Does anyone here know the basic stuff about Fourier transforms?
 
37 mins ago, by Balarka Sen
throws a table at @Khallil
 
Ice Boy, do you know basic Fourier series?
 
you were out for only 37 minutes @Khallil
^_^
 
Can anyone see my messages?
 
11:05 PM
Nope, we can't, @Analysis.
Hahaha!
 
:D)))!
) = Ha
 
A
n
a
lys
i
s
 
01:00 - 19:0019:00 - 00:00

« first day (1508 days earlier)      last day (3506 days later) »