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3:00 PM
@JasperLoy Not yet, just trying to find someone who I can work under to possibly publish some of it
 
@teadawg1337 But who would you need to work under if you are the original author?
 
I mean in the future, I don't know what I'm gonna do with the work that I've already done
The basis of my work with the Basel problem is on MSE, so it belongs to Stack Exchange
 
What you write belongs to you.
 
Yes, but I don't show my real name on my MSE profile, so I don't know how to prove that it's my work
 
@JasperLoy there was a long conversation about it and I followed it back. I was curious what the question was.
 
3:04 PM
@robjohn I see. You must have been following all my interesting conversations then. =)
 
@JasperLoy All of them.
 
morning folks
 
morning @mike
 
@MikeMiller Hey there. Back to the new term?
 
yup, @robjohn
 
3:06 PM
@MikeMiller taking any interesting classes this term?
 
mostly doing lots of reading and seminars
 
I read the chat transcript.
 
@MikeMiller That can be very interesting :-)
 
Do seminars come with food and drinks?
 
@JasperLoy Is it more or less entertaining than the phone book.
 
3:07 PM
No, @Jasper.
 
Phone book, what's that?
 
it looks like I'm the only one playing StackEgg
 
what's stackegg?
 
go to the main page.
 
@robjohn More of course. Some math books are written like phone books though.
 
3:08 PM
ah, i saw it, but didn't click it.
 
oh! i get it, it's easter coming up.
 
that's a weird game
 
Good Friday will never be good for me until I get well.
Sorry if I talk too much in chat. Those who wish to ignore me may click the ignore button, thanks.
 
Hi, anyone for ring theory ?
 
3:46 PM
@JasperLoy got my exam back for dynamical systems and I performed horribly :(
@JasperLoy there are chemistry majors in my class that got 100 :(
 
@ᴇʏᴇs Sorry about that. It's not your fault.
 
@JasperLoy It is, I took a gamble because I didn't understand one concept out of all the topics so I hoped it wouldn't be on the exam but there was 20 points worth of those topics on it lol
 
@ᴇʏᴇs OK. But hey at least you did not screw up your life like I did.
 
@JasperLoy I'm just fixing mine earlier, you'll fix yours very soon
 
@ᴇʏᴇs I hope mine is still fixable. You must pray for me. I am going to bed. Good night.
 
3:58 PM
WTF is this stackegg thing ?
 
@LeGrandDODOM A Tamagotchi
 
4:18 PM
It's nice to see how many fail to give the correct answer as regards the parity of $0$. :-)
 
It's even, 'course.
 
I think that might be a good interview question (and the interviewer might have much fun).
 
What, parity of 0? But it's patently obvious!
 
@BalarkaSen I was just talking to a friend of mine, back from high school, he told me he prepare a proof for $0$ is both even and odd.
 
He is wrong.
 
4:27 PM
@BalarkaSen Of course. I let him think of it for a while.
 
A parity of an integer, by definition, is on which equivalence class mod 2 it belongs. 0 belongs to [0] in Z/2Z as 0 is divisible by 2, hence it's obviously even.
 
I have to buy some food for my pets. When I enter the store I'll ask the guys there if they know how $0$ is in terms of parity.
 
Pet store clerks are usually not the best sources of reliable mathematical information. It's a matter of self-selection.
 
The MSE StackEgg has officially "graduated" to become a full member of the site
 
has it taken over the internet yet?
 
4:34 PM
We've done that once, according to the leaderboards
 
Yeah, right, some have done some good schools. Just curious about that. I'm on the way to them. :-)
BBL
 
4:56 PM
Any hint on how to evaluate $\displaystyle\lim\limits_{x\to\infty}\frac{x(e^{\sqrt[x]{x}-1}-1)}{7\log{x}}$?
 
Someone help me with the StackEgg thing, this other user is hell-bent on screwing everything over by only voting for "Ask"
 
@Chris'ssis Hi again, I just saw your answer !
 
Back from the store. No one knew the answer! One said "Does $0$ have a parity?" and th eother one said $0$ is both even and odd.
 
The store ?
 
@Ramanewbie The solution is as I mentioned. I misunderstood teh question a bit, but that way is just fine.
@Alessandro That limit flows really naturally.
$$\lim\limits_{x\to\infty}\frac{(e^{\sqrt[x]{x}-1}-1)}{\sqrt[x]{x}-1}\cdot \frac{\sqrt[x]{x}-1}{7\log{\sqrt[x]{x}}} $$
That's all.
That is $1/7$. Q.E.D.
@Alessandro To summarize, all you need is to use well-known elementary limits.
 
5:12 PM
@Chris'ssis Doesn't look like anything "elementary" to me from his point of view...
 
$$\lim\limits_{x\to\infty}\frac{(e^{\sqrt[x]{x}-1}-1)}{\sqrt[x]{x}-1}\cdot \frac{\sqrt[x]{x}-1}{7\log{\sqrt[x]{x}}}=\frac{1}{7}\lim\limits_{x\to 0^{+}}\frac{e^{x}-1}{x}\cdot \lim\limits_{x\to 0^{+}} \frac{x}{\log{(1+x)}}$$
 
I see, you made a transformation such that $x\mapsto\sqrt[x]{x}-1$
 
@teadawg1337 Yeah, for a clearer picture of the limits I used.
BBL (30-60 min)
 
I spend too much time on integrals and series, I often forget many of same methods are applicable to limits
Which is odd, considering how often limits occur in my work...
...
 
@Chris'ssis I think I'm missing something, how did you go from $\log{x}$ to $\log{\sqrt[x]{x}}$? (I mean in the first step)
 
5:24 PM
@Alessandro You have $x$ on top. I took it from there I put it under the log.
 
@Chris'ssis oh, of course
 
@Alessandro $\frac{x}{\log(x)}=\frac{1}{x^{-1}\log(x)}=\frac{1}{\frac{1}{x}\log(x)}=\frac{1}‌​{\log(\sqrt[x]{x})}$
 
Hi! What subject is better to study first, non linear or linear programming? :)
 
Let $H, G_1, G_2$ be groups. If i know that $H \times G_1 \cong H \times G_2$ does it follow that $G_1 \cong G_2$.
 
I give up on formatting that, you know what I intended it to appear as @Alessandro
And I spent so much time formatting that I didn't realize I was beaten to the punch...
@Saal Well, $H\cong H$ is it not? Doesn't $G_1\cong G_2$ directly follow?
 
5:30 PM
I'm not sure how to formalize it
 
Hallo
 
@Chris'ssis @teadawg1337 thanks for your help, I understand now
 
Hallo @Owatch! Deutsch?
 
@Owatch guten Abend
 
@SaalHardali Dunno, I'm not an expert in group theory.
 
5:42 PM
@Hermine No
 
Typo then?
 
Ich ist ein Mann
All I learned from duolingo
No I like the way it sounds, so I say it
 
I think that proves that you don't speak German @Owatch
 
I don't, never claimed to.
I speak French
And English
 
Me too :)
 
5:44 PM
You speak French?
 
Je suis en train de apprendre allemand aussi :)
Oui, mais pas tres bien :P
 
I see.
Is it on your own?
 
je m'appele Isabelle
 
Nope, at my University, they give us free language courses
I learnt french there
 
Nice, I'd like to learn it too.
 
5:46 PM
Are you implying you don't actually speak French @Owatch? :P
 
Aber ich weiss nicht vielen Worten auf Deutsch :(
 
No, I do.
I know what she said, I can speak it.
Ca cera mieu si je prends du temps pour ameliorer ma grammaire.
 
Tu es francais @Owatch?
 
'Twas meant to be a tease, @Owatch
 
Ma maire est francaise.
J'ai vecu en France pour peut-etre quatre ans/
 
5:49 PM
Je vais y aller
veux*
 
Mais j'ai un passeport francais, donc qui, je suis Francais.
(Je suis dans l'etas unis pour l'instant, et je suis aussi American)
 
@Hermine did you take courses also in German?
 
J'ai toujours etait enseigne en Anglais, et mon francais souffre beaucoup malheuresement.
Mes amis Francais sont decu. .
Ou veux tu aller?
Bad news Tee Dog
I completed my test last week, 10/15 questions. But we were supposed to do 12.
Nobody did 12 as far as I know.
In any case, we are permitted to do additional problems next lesson under test conditions for half points if we wish.
So I must practice some more.
I think that 12 problems in 1 hour and a half is a lot considering the work pace of other students is similar to mine.
 
I cannot help you under test conditions
12 problems in an hour and a half is very doable
 
It takes me like 20m to do one!
Ok maybe less
If it takes me 15m per question, that requires 3 hours to do 12.
 
6:00 PM
You say you need to do practice problems? Are those the ones on which test conditions are applied?
 
No
I don't need to do practice problems, but I should if I want to be good at solving them
In any case, I cannot at the moment as I have other classes to do work for.
So perhaps tomorrow.
Or tonight if I finish in time
I will start them myself
 
@Alessandro, yes, I'm in my second semester of my german course :)
@Owatch je ne sais pas, peut etre Marseille, Paris (comme tout le monde :P )
 
Paris is okay.
I was say it's a bit overrated. But I suppose that depends on your expectations.
 
Huy
@Owatch: How is it overrated?
 
Yes, I can see Paris is very idealized...
 
6:08 PM
@Huy People are very cold. The city is sometimes a bit dirty too, not terribly more than other cities, but it seems more visible.
 
Huy
@Owatch: It seems terribly dirty to me but I didn't know that people go there expecting something else.
 
I have been to London, and NYC
 
Wow, I've never left my country
 
@columbus8myhw was Asaf here?
 
NYC was a bit better I thought, and most people travelling there think of it as some sort of paradise.
Or they expect it to be better than it is.
If you have been there and lived there, sure. It is normal/expected.
 
6:13 PM
@Chris'ssis why is that nice? Is there any reason why they would think it is odd?
It seems disturbing to me.
 
@Huy Do you live in Paris?
 
Huy
@Owatch: No.
@Owatch: I have never heard anyone thinking NYC is some sort ofparadise.
 
I meant Paris
 
Huy
@Owatch: Same applies for Paris.
 
@robjohn Maybe they consider $0$ as a kind of special number or so with a special property as regards the parity.
 
6:18 PM
How to get the exact maximum of this polynomial : $10x-\frac{10}{13}x^2$
 
You did not like me saying it seemed overrated did you?
 
Huy
I just wonder why it should be overrated.
 
A paradise is an exaggeration. People expect it to be romantic and pleasant.
 
Huy
I found it rather romantic.
 
Just like the stickers on some motorcycles.
"I love nothing, I am a Parisian"
 
6:25 PM
@robjohn I just asked on a certain network this question and I receive only wrong answers. It looks like that most of them say it's neither even, nor odd.
 
@ThomasAndrews I don't see where the problem is (see my comment)
 
I have no context for that statement, @EnjoysMath.
 
oh,
you gave an example. Lemme check it out
 
Oh, that statement. You are definitely wrong. There aren't many normal subgroups of $S_n$.
 
I thought $A_n$
$S_{i_1}=\{e,(1,2)\} \implies \tau S_{i_1}\neq S_{i_1}\tau$
$(1,3) (1,2) = (3,2), \ (3,2)(1,3) = (1,2)$ QED
in fact, $(u,v) (1,2)$ does the same thing
so I don't see the problem yet
 
6:31 PM
@Ramanewbie Take the derivative and solve for x such that $f'(x)=0$
Unless you haven't learned calculus yet?
 
Aha, I stumped Thomas Andrews
 
GAH! I need money.
 
$_$
 
Huy
@DavidWheeler: Do some work and you'll get money.
 
@DavidWheeler what for?
 
6:53 PM
@Huy I intend to. However-my situation is this: I have a job (well, I will have), but it's in North Dakota, and I'm in Texas.
I think I have the moving expenses covered, now I need first+dep for a place to rent, and food to munch till my first paycheck.
 
Huy
@DavidWheeler: You should get a job in Texas or move to North Dakota.
 
Yes, I prefer option number 2. Texas is a terrible place to work. Salaries are low, and employer benefits are well below national averages. Laws are pretty staunchy skewed against employees in favor of employers, as well.
 
Huy
Is it common in the US to not have much of savings? (because you say you only have your moving expenses covered and need first&dep for rent)
 
@Huy-I don't know. But in my case, no I don't have much savings. Personal reasons.
 
Huy
I see.
 
7:02 PM
When my wife committed suicide, I sort of let everything go, for a few years.
 
Huy
I've seen a lot of people on r/personalfinance financially living on the edge and I just find that weird.
I'm sorry for your loss, @DavidWheeler.
 
:(
That is an awful thing.
 
There was this "credit bubble", for a while, credit was too easy to obtain, based on the premise the economy would continue to improve. The first decade of this century showed that optimism was unfounded. Mass foreclosures ensued, a lot of banks needed to be bailed out, due to unwise mortgage investments.
 
Huy
@DavidWheeler: I know of that bubble.
 
So when it's time to "pay the piper" the savings are the first thing to go.
 
Huy
7:08 PM
=(
 
This, in turn creates a dearth of liquid capital, hindering further recovery.
 
Huy
I wish to never be tempted to take out a loan but I don't know if I can resist.
 
Loans aren't necessarily bad-suppose you own a trucking company, and can double your earnings with another truck. If the cost of the loan on top of your other expenses is still less than double your current costs, it makes sense to borrow the money.
 
@TedShifrin, et al. - I am looking for a quote which I believe was attributed to Riemann that went something like, "The difficulty is not in the proofs, but knowing first what to prove."
 
Huy
@KajHansen: Riemann indeed. "If only I had the theorems! Then I should find the proofs easily enough."
 
7:13 PM
@Huy, thank you so much. I've been Googling for a while with no luck!
 
Huy
@KajHansen: I started googling 1 minute ago.
 
What. the. hell.
 
Huy
@KajHansen: After your daily maths session, you should practice some more googling.
 
So it seems :P
 
Huy
@DavidWheeler: Usually, over here loans are taken out for acquiring flats or houses. I think the banks require one to at least have a fortune of 30% of the loan they want to acquire.
@DavidWheeler: But for most people it is never paid back. Just the interests. So the house/flat basically belongs to the bank.
 
7:16 PM
That's a sound lending practice.
 
Huy
Is that the same in the US?
 
I'm not sure about now...for a while Fannie Mae was floating loans with 10-15% down. The lower down payment was typically made attractive to lenders by rolling in PMI (default insurance).
 
Huy
That's really low.
 
These loans were then bundled, and re-sold to investors as "derivatives"
 
Huy
I see.
 
7:21 PM
@teadawg1337
 
7:33 PM
I often hear questions like "Why do you attend such problems, calculations?" or "Who cares about them?" or "What are they good for?". Now, more than ever, I'm sick and tired of these questions.
 
How do I prove that these all are composite?
$10001$, $100010001$, $1000100010001 ....$
@robjohn ^
 
@BalarkaSen, @JulianRachman, et al. - Pete's posted a new problem set for us for those who are interested: math.uga.edu/~pete/4200HW_six.pdf
 
"not everyone agrees that manifolds should be second countable" is technically true but nonetheless misleading; anybody working on locally euclidean spaces that aren't second countable is far from the mainstream
and his theorem of Whitney assumes second countability
 
Cool cool. Thanks for the clarification @MikeMiller
 
indeed every $n$-dimensional topological manifold can be embedded into $\Bbb R^{2n}$; this is recent, not due to Whitney (who did the smooth case). Whitney's proof works for topological manifolds to show that they embed into some big $\Bbb R^N$; his reduction of $N$ to $2n$ (or even $2n+1$) is not valid in the topological category
 
7:51 PM
@teadawg1337 yes, I just saw your answer when I pinged you...
 
@Ramanewbie evaluate at $x=\frac{13}2$
 
@teadawg1337 But I haven't really learn that yet, indeed. I wonder if we cannot get the canonic way of the polynomial and then get the coordonates of the maxinum ?
@robjohn I know it's between 6.48 and 6.52, but I can't manage to prove what the exact value is...
@robjohn Is it exactly $\frac{13}{2}$ ?
 
@Ramanewbie Have you tried taking the derivative and setting it to $0$?
 
@robjohn I don't know the formulas for the derivate...
 
@Ramanewbie well, I guess you could complete the square.
 
7:56 PM
@robjohn What do you mean ? I've been thinking of the canonical way so far, do you think it's a good idea ?
 
If I have a matrix min. polynomial and I want to find the equation for $A^n$, is there a straight way to get the equation
 
@Ramanewbie completing the square: $10x-\frac{10}{13}x^2 =\frac{65}2-\frac{10}{13}\left(x-\frac{13}2\right)^2$
 
@Ramanewbie Look at the graph of the function to understand the point.
 
@Chris'ssis I could find an approx result (6.5) but what I need is the exact x value
@robjohn That's the canonic way, yes.
 
@Ramanewbie @robjohn told you the exact value.
 
8:03 PM
@Ramanewbie You are troubled by this little question :O :D
 
@Chris'ssis yes, thanks @robjohn
@Sawarnik I'm fine now that I've found the clue to find the solution...
@robjohn Could you explain how you got the canonic way ?
 
Factor out $-\frac{10}{13}$: $10x-\frac{10}{13}x^2=-\frac{10}{13}\left(x^2-13x\right)$
Then remember that $(x-a)^2=x^2-2ax+a^2$
So $a=\frac{13}2$
Thus we add $\frac{169}4$ on the inside of the parentheses and $\frac{130}4$ on the outside:
 
@robjohn thanks
 
9:00 PM
Hey
There is something I don't understand, a group action on a set A means g in G acts as a permutation on A in a manner consistent with group operations in G.
 
Hello @Karim
 
What does it mean to be consistent with group operation ?
 
You should look at the actual definition of a group action. What they mean by that sentence is that $(gh) \cdot a = g \cdot (h \cdot a)$.
 
oh I see I mean consistent that is intuitively when we apply group gh then apply on a
it will be same as applying g on the element of the set given by ha ?
 
9:22 PM
0
Q: Sign with Fourier transformation, convolution, periodicity

user159870Let $x(t)$ be the sign with Fourier transformation $$X(\omega)=\delta(\omega)+ \delta(\omega-\pi)+\delta(\omega-5)$$ and let $h(t)=u(t)-u(t-2)$. Is $x(t)$ periodic? Is the convolution of $x(t)$ with $ h(t)$ a periodic sign? Can convolution of two non-periodic signs be a periodic sign? How ...

 
9:40 PM
We also require that $e\cdot a = a$, that is, the identity of $G$ induces the identity permutation. It's very similar to how the group of multiplicative units (of a field) acts on a vector space.
 
10:15 PM
I still don't know if I should learn from Clark's notes or Simmons
 
So I've failed 4/5 midterms so far :(
 
On what?
Also, I'm not sure if people who have answered a question are notified if the question has been migrated. Does anyone know?
 
Can anyone help me understand what a characteristic polynomial can do that a minimal polynomial cant
 
10:35 PM
it's easily computable and its coefficients have the trace and determinant, so that those two values tell you something about the charpoly
 
Can minimal be used to find the kth power of a matrix?
 
It also tells you the algebraic multiplicity of an eigenvalue, which bounds its geometric multiplicity (is an upper limit for the dimension of an eigenspace). Minimal polynomial gives no information about that.
 
when would I need to know the multiplicity of an eigenvalue?
 
Well, you might want to find an eigenbasis, if one exists.
That diagonalizes your matrix, making powers easy to compute.
 
because then it's just the powers of each individual element along the diagonal right?
 
10:49 PM
'zactly
 
11:03 PM
oh I see @DavidWheeler
that is nice analogy
 
11:30 PM
Hello @robjohn @DanielFischer
$|y|=e^{t+ \sin{(4 \pi t)}+c} \Rightarrow y=\pm e^{t+ \sin{(4 \pi t)}+c} \Rightarrow y=\pm e^c \cdot e^{t+ \sin{(4 \pi t)}}=C \cdot e^{t+ \sin{(4 \pi t)}} $

Is the above correct or can't we just set $\pm e^c$ equal to C?
 
@evinda Hallo, bist du noch wach? Es ist nicht gesund, Mathematik der ganzen Nacht zu lernen :P
 
Does anyone have a PDF copy of Slater's "Confluent Hypergeometric Series" I may have?
Published 1960
Honestly the best book on this subject I have yet seen in my travels
 
lol @Alessandro kanst du deutsch sprechen bist du from Deutschland ?
 
"travels"
 
@Alessandro Hallo!!! Ja, ich bin noch wach.. Ich habe im Moment viele Aufgaben auf. Bis am Donnerstag muss ich in 2 Fächer Aufgaben abgeben.. Was gibt es neues bei dir? :)
 
11:34 PM
@jm3243 Who is it by?
 
Lucy Slater
@Christopher
 
@KarimMansour Ich komme aus Italien, aber wohne in Deutschland
 
I see
 
oh sorry, the link I was going to provide is only an table of contents
 
Ich bin von canada aber ich weiss ein bisschen deutsch
 
11:41 PM
@evinda nichts besonderes, ich habe die ganze Woche Ferien, deshalb lerne ich Deutsch für die B1 Prüfung
 
@Christopher Thanks for trying at least!
Hey, at least you were able to find that! I couldn't find anything
I think it's funny because it's cited by hundreds yet not a single thing online anywhere about it
e.g. here is a paper that mentions it a lot: campus.mst.edu/adsa/contents/v8n2p16.pdf
 
Made a 2 on the Putnam!
(goal was a 1, didn't study, just showed up)
 
@GBeau Congrats!
 
Verbringst du die Ferien in Deutschland ? @Alessandro
 
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