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r9m
8:10 AM
@robjohn $H_n^2$ of course :-) (I saw your proof of $H_n^{(2)}$ :D !! Awesome !!)
bbl lunch :)
 
hello
 
@Committingtoachallenge here
@daOnlyBG hello :-)
 
What's going on?
 
not much, how about you?
 
I heard a cheesy yet lulzy math joke this evening
 
8:18 AM
ok?
 
A man enters a math-themed café and orders the "Mobius steak." What did he say when it arrived?
 
i wanted it cooked on both sides?
 
"I'll never be able to finish it."
 
```````````````4kllllllllllllllllllllllllllllllllllllllllllllllllllllll
 
@daOnlyBG I don't get it.
 
8:21 AM
There was a dog on my keyboard, no joke. I am dogsitting this tiny little dog
 
@Committingtoachallenge the dog only landed on 4 buttons? :p
 
That's one tiny dog
shih tzu?
 
The keyboard is not very good, so it only takes one key input at a time. New keyboards and gaming keyboards can take multiple
 
Greetings
 
Greetings & Salutations
 
8:28 AM
I have no idea what the dog is to be honest, I have never had any in my life and have had friends with mostly standard dogs e.g. Golden retriever, Huskie, Labrador, dalmatian
@Chris'ssis Hello Chris's, any interesting integral today
 
@r9m I didn't see but I might create it soon. By the way $$\LARGE \text{ I HAVE NEWS!!!}$$
 
$$\LARGE \text{The book is complete?}$$
 
No :-)
@r9m I'm very close to the solution of (I'm afraid not to received the bounty from myself - I hope not)
 
$$\LARGE \text{VERY NICE!}$$
 
@Chris'ssis I don't think you can grant bounty from yourself.
That's not possible.
 
8:31 AM
disabling ChatJax
 
@BalarkaSen Well, I should if I deserve it ... (still, that question will appear in my book)
 
@IceBoy Why friend :)
 
Yes, morally, @Chris'ssis. But the system in MSE won't support it...
 
@Committingtoachallenge just kidding pal :)
:D
 
@BalarkaSen Anyway, I don't think any will be able to do it soon (maybe in a few months or years).
 
8:33 AM
seriously disabling chatjax
@Chris'ssis "any" excluding you, perhaps?
 
@BalarkaSen You know me, I'd have some advantage since I worked on tons of similar questions ... (that's all, but not a guarantee)
 
right
 
@Chris'ssis have you ever thought about posting your most difficult ones on mathoverflow?
 
They would probably trivially solve them, I might be wrong though\
 
@IceBoy # of unsolved integrals in MO is infinitesimal
I'd think MO doesn't care about solving integrals ...
 
8:38 AM
just a suggestion :-)
 
@IceBoy Those guys will close my questions immediately although I don't know if they (or a part of those that vote for closing) were really able to solve them ...
 
...ok, that is their loss
 
r9m
@Chris'ssis $$\LARGE \text{Great !}$$ :D
 
Hi @Ethan
 
hey skull
 
8:44 AM
long time no see pal :-)
 
yes long time no see lol
 
hey @Ethan
whatcha been upto?
 
(removed) <---for old times' sake :D
 
cs is pretty vague soz
 
oh noes
 
8:48 AM
(removed)
 
why don't you fight it?
yeah. well i get it in some sense.
don't sweat it.
 
we all get that feeling...
7 mins ago, by Ice Boy
(removed) <---for old times' sake :D
 
soz
that sort of thing
alright i wont anymore
will try atleast
sorry if im being annoying
 
come'on guys, stop it
 
i can not do it, like i can force myself
but it just feels better to do it
by feels better i mean it is less painful
i havnt done any math in a long time =(
 
8:57 AM
what the hell @Committingtoachallenge
 
othewise id post some cool identity for you guys
 
stop reposting those
ughh
ignores the two
@Ethan You should start doing it ;)
I haven't really done any number theory these days. Only a bunch of topology and algebra
 
@Committingtoachallenge surrender
yes
thanks :-)
 
r9m
(removed) -_- !! .. if every hair in my head was to be removed with each (removed) .. I'd go bald in matter of days ! sigh
 
hi
Are there people here that submitted papers to "American Mathematical Monthly"?
 
9:09 AM
In this chat room? Idk, on this site yeah definitely.
 
9:27 AM
I would like to ask how much time it takes to get a notification. But I don't think it is a question for math.SE site.
 
I need help!!!
0
Q: Evaluation of a tough double integral

Chris's sisThis is an integral coming from personal research, and very important to me, but it does not seem an easy job to do. If a solution is not possible then I'd be glad with a closed form only. $$\int_{[0,1]^2} \frac{(1-x-y+x y+x \log(x)-x y\log(x)+y \log(y)- x y\log(y)+x y\log(x)\log(y))\log(1+x y)}...

@Ethan ^^
@r9m ^^
@Committingtoachallenge ^^
@BalarkaSen ^^
 
@Chris'ssis What does $[0,1]^2$ mean? Both integrals are just $0$ to $1$? I haven't seen this notation before
 
@Committingtoachallenge Yeah
 
Doesn't look like too much fun sorry
lol
 
@Committingtoachallenge the integration is done over that domain in $\Bbb R^2$
 
9:32 AM
@BalarkaSen I know now, I was just clarifying
I am looking now @Chris's
 
@Committingtoachallenge Thanks!
 
r9m
@Chris'ssis looks crazy !! :O
 
@r9m It is exceptionally important to me for some reason ...
 
r9m
@Chris'ssis I read that :-) .. looks fearsome ! does the integral arise from some Euler Summation ?
 
@r9m No
 
r9m
9:38 AM
okay ! its usually very difficult for me to identify the anti derivatives of these expressions ! :(
 
Change of order is significant in reduction
 
r9m
I would naively suggest $t = 1+xy$ and it becomes a problem of identifying anti derivatives of expressions involving $log$ and $Li_2$ .. but Ilazy lol :P
_/_ ! best of luck tackling that monster !
 
@Chris'ssis What does this solve? Is there any hope I could even solve this?
@Chris'ssis I haven't done stuff like this for a year which was Calculus III
and obviously you don't want a numerical solution
I upvoted
 
@Committingtoachallenge No, I want a closed form.
 
@Chris'ssis in the title of your book, are you going to put the word "Series" first or "Integral"?
 
9:53 AM
@IceBoy Integrals will apear first: 1) Integrals - 2) Series - 3) Limits
:D
 
Why not limits, series and integrals? Isn't that more available?
Oh sorry I misread the question. I thought it was order of covering the topics. Integrals, series & limits, is a good title order
 
Actually of the three, series are studied first at school, no?
 
Limits normally?
 
Sequences, series...
 
@r9m does that work?
 
r9m
9:58 AM
@Chris'ssis I'm not sure .. I haven't tried it yet
 
@Chris'ssis Is this not your normal sort of integral problem?
 
@Committingtoachallenge this one seems hard or I'm not inspired enough now ...
 
10:25 AM
does anyone know how to plot $x^a$ with Maplesoft?
 
@r9m Geometry!
 
r9m
@Sawarnik ??
 
$AB=AC$. $DB=DC$. $DE \perp AC$. $DF=EF$.
@r9m Prove $AF \perp BE$. Do you have time?
 
r9m
r9m bot : what have you tried ?
:18414539 its really a simple problem
 
10:40 AM
@r9m :O :O How?
 
r9m
@Sawarnik atleast its simple enough if you are willing to use coordinate geometry :)
 
No, not coordinate :(
@r9m :(
 
r9m
@Sawarnik I watch low budget Indian commercial movie :P I try later ?
 
ok :(
 
11:07 AM
I also wanna post this one, it's about finding the closed form of $$\int_0^1 \frac{(1-x+x\log(x))\operatorname{Li_2(x)}}{(x-1) x \log(x)} \ dx$$
 
@Chris'ssis Somewhat similar?
 
@Committingtoachallenge What do you mean by somewhat similar?
 
@Chris'ssis To the longer problem?
 
@Committingtoachallenge Not really, it's a different one.
 
What is $\operatorname{Li}_2(x)$
 
11:11 AM
@Committingtoachallenge dilogarithm
 
Where would one normally learn the dilogarithm? Complex analysis?
 
@Chris'ssis That combination I was trying to solve yesterday is a lot lot harder than it looks
 
Why does noone on here care for game-theory, graph-theory, coding-theory, design-theory or optimisation-theory? I see very few users in these fields
 
eleven thousand eleven hundred eleven = twelve thousand one hundred eleven
 
11:15 AM
11000 + 1100+11 = 12111
 
:D
 
@Committingtoachallenge Because people who do care about it are to busy doing or teaching it.
 
@Alizter What does that imply about fields with many users? Are you saying that the fields(listed above) aren't accessible(without specialised training)?
 
@r9m oh, there was trilogarithm though ...
$$\int_0^1 \frac{(1-x+x\log(x))\operatorname{Li_3(x)}}{(x-1) x \log(x)} \ dx$$
 
r9m
my god ! <(O_O)>
 
11:20 AM
AAAAhhhhh!!!
(O_o)
 
@Committingtoachallenge No. The people in this chat are arbitrarily specialised.
 
@r9m
0
Q: Finding the closed form of $\int_0^1 \frac{(1-x+x\log(x))\operatorname{Li_3(x)}}{(x-1) x \log(x)} \ dx$

Chris's sisHere I have a question I just received, and still trying to find a proper starting point $$\int_0^1 \frac{(1-x+x\log(x))\operatorname{Li_3(x)}}{(x-1) x \log(x)} \ dx$$ What starting point would you propose?

 
also
Game Theorygametheory.stackexchange.com

Q&A site for researchers, academics, and practitioners of strategic decision making

Closed after 9 days in beta.

 
@Alizter Oh sorry, I mean't from M.SE not the chat
 
There are not too many people
@Committingtoachallenge Yuh. This was the Game Theory SE. See how popular it is.
 
11:24 AM
@Alizter They specialised the SE wayyyy to much, they could have thrown heaps of fields in with game-theory
 
r9m
@Chris'ssis (+1) but I'm not good with polylog integrals .. IcrywhenIfaceone !
 
@r9m Icrieverytime
 
@Committingtoachallenge There is Gamification SE soon, Economics, Here, MO there are experts scattered around the place. Just not in one place
 
@r9m lol, a potential hater downvoted me ... :-) (I hope it's not one of the integration gurus - it would be sad)
 
r9m
sigh
 
11:35 AM
@r9m It's unbelievable that I found a potential way of getting the closed form of the question with the bounty. I ask myself: how can be that real?
@r9m still, I'm not done :-(
 
r9m
@Chris'ssis bbng ?
 
@Alizter OK
 
@Chris'ssis What was the form??
 
r9m.
 
11:38 AM
I can't see where you posted the form?
@Chris'ssis $\frac{6048077 \pi }{120064349}$ ;P
 
@Committingtoachallenge :/
 
@Sawarnik Are you alright Saw?
 
Yes, Commit.
 
@Sawarnik Why the :/ face?
 
@Committingtoachallenge lol :-)
 
11:45 AM
@Committingtoachallenge That fraction :/
 
@Chris'ssis Just another day of a closed form expression guessed from the numerical result xD
 
@Committingtoachallenge Good, good! ;)
 
@Committingtoachallenge Ah!
 
Hi people
 
I and my last questions greet you
 
11:56 AM
hi
 
hi
 
@UserX Welcome
 
greetings
 
@Chris'ssis separate in 3 integrals
 
@UserX you mean in 3 divergent integrals?
 
12:05 PM
@userX Would @Chris's Really miss something like that?
 
Lol they diverge
 
12:17 PM
@Chris'ssis what's the answer? Is it rational?
 
@UserX I don't know yet ...
 
$\frac{115233}{250000}$
That's what wolfram gets... Isn't it a little weird?
 
@UserX Is this the answer to my integral?
 
I'm not sure. Maybe.
It doesn't represent it as an approximation, could it really be rational?
 
@Chris'ssis I decided to ask about the combination question on the main yesterday. I need some more rep so I can put a bounty on it :P
 
12:27 PM
@UserX Which integral friend?
 
Chris'ssis's one
Should I sleep, finish an essay about democracy or try to cram the rest 220 pages of euclidean geometry?
 
@UserX Alternate sleep and cram.
 
depends on how tired you are
 
12:44 PM
@UserX Which one sorry?
@UserX 220 pages of geometry sounds like the most fun
 
I decided to eat
I'll write the essay, then study EG, while fighting sleepiness
 
@UserX This one you said equals $\frac{115233}{250000}$ chat.stackexchange.com/transcript/message/18414861#18414861 ?
 
@UserX That's best/
 
study EG first, then write the essay while fighting sleepiness
then sleep and start again with EG
this is for a math test right?
 
^better.
You write real fast when fighting sleepiness.
 
12:57 PM
good point^
:-)
Geometry requires clear visual thinking.
 
I don't write faster when I am fighting sleepiness haha, I just feel like giving up(but don't)
I might call an early night tonight(11:00PM)
 
Heyta
 
hi pal, looong time no see
 
I am looking for a document, but can not find it =/
 
@UserX and things in Geometry are so much easier to spot with fresh eyes...
 
1:06 PM
mathworld.wolfram.com/SerretsIntegral.html trying to find the 1844 paper
 
@N3buchadnezzar: Hiya there :D Could you link me your integral cookbook again please , I seem to have lost it.
 
@Committingtoachallenge When you can't give up, and you are sleepy, you do write fast.
I know that well.
 
@Sawarnik I get about 4 hours a night and I am a counter example to your Theorem $\blacksquare$
 
Unfortunately to go to uni every day, I have to get up at 5am and get on buses and as you know I am normally up until 1am(+10Time)
 
1:08 PM
@Committingtoachallenge: Ditto
 
Anyway I shall sleep early tonight, because I finally get to rest for a little :).
 
@N3buchadnezzar: Thank you so very much :D Also, that paper you're searching for is as hard as nails to find. It is most likely that you will find the paper in Versailles, France inside of Serret's tomb. lol
 
@Nick Lol
@Nick I want to reffer to it in my book, but I hate reffering to papers I have not read yet.
 
@Committingtoachallenge I am a proof to my theorem.
@Committingtoachallenge Ditto.
 
@N3buchadnezzar: It's not discoverable online. Maybe some library or book has it. You can definitely get your hands on it if you track down some of his friends from École Polytechnique. (though, they're most likely dead as well)
 
1:21 PM
I will search my math libary perhaps they have something
@Nick You like my notes? =D
 
@Committingtoachallenge I'm looking at your reading list and I'm seriously considering following in your footsteps. It's so difficult to stay motivated without any goals.
 
Wait, are there not communities on the internet whose sole purpose of existing is to digitize important scientific matter and bring it to the hands of the general public?
@ChantryCargill: Get goals, sirji.
 
Hi @Finn
 
have we met before?
 
Do you mean like in a previous life?
 
1:27 PM
@Nick Okay, I'm committing. I'll see how well I can stick to this during teachers college.
 
@user130018: Stop playing. How do you know my reel name?
@ChantryCargill: Good luck! Godspeed!
@N3buchadnezzar: This is Norwegian, right?
 
@N3buchadnezzar: What did you use to write this? (ie, which latex editor did you choose?)
 
TeXnicCenter
 
1:32 PM
@user130018: What? How do you know?
 
@Finn Because I read it
 
Nick is perplexingly perplexed. ie, he is confused
@user130018: Care to reveal your identity, Racer X
 
@Semiclassical
 
$\lim_{x \to 0} \frac{sin (1-cos x)}{x}$ :) how to calculate this ? :) im very new to limits :) without L Hospital rule
 
@Finn I don't give out information from my personal life on the internet
 
1:37 PM
@user130018: ... I meant your other pseudonym. I assume you're a regular in this room who's created a new account.
@TheArtist: What is $\lim_{x \to 0} \frac{\sin(x)}{x}$ ?
 
Darn he is not here.
 
@Finn Nope, this is the only one I've ever had
 
@DanielFischer
 
@Nick its 1 ....but over here it's 1- cos x , the angle is not x
 
curses
OK, nevermind, I misunderstood the question.
 
1:40 PM
@user130018: whoops, sorry then. I sincerely apologize for the rudeness
 
@Finn What rudeness
 
@BalarkaSen Yes?
 
@BalarkaSen 0
 
@TheArtist: Also, $1 = \frac{1}{1} = \frac{1 - \cos x}{1 - \cos x} = \frac{\text{potato}}{\text{potato}} = \frac{\text{tomato}}{\text{tomato}}$
 
@DanielFischer Am I right in thinking that the genus of the Riemannsurface of $w^3 = z$ over $\Bbb P^1$ is $1$, i.e., it's a doughnut?
 
1:42 PM
@Nick then? Ok yes but how is this going to get the answer? :)
 
@TheArtist OK, so the problem is to compute $\lim_{x \to 0} \frac{\sin(1-\cos(x))}{x}$, right?
 
@BalarkaSen yes :)
 
Why don't you expand the numerator by the addition rule?
And use fullstops instead of smiley faces, please. ugh.
 
@TheArtist: I can't explain it good. Just use L'Hosp and be done with it.
 
@Nic
 
1:44 PM
@Nick , this would have worked if it was $\frac{sin (1-cos x)}{1- cos x}$ :p then that's potato/potato is same as what you said :p
 
@BalarkaSen I don't know. By doughnut you mean torus?
 
@TheArtist You can multiply a factor of $\frac{1-\cos(x)}{x}$
@DanielFischer yes. whatevs.
 
@TheArtist : $\frac{\sin(1 - \cos x)}{x} = \frac{\sin(1 - \cos x)}{1 - \cos x} \cdot \frac{1 - \cos x}{x}$
 
@Nick but it's not the same function, so that won't apply.....this is for my gf :) she hasn't learnt L hospital :) That is why :) so can't tell her this :)
 
My claim is that the RS of $w^3 = z$ over C is homeomorphic to a torus minus two points.
 
1:46 PM
@BalarkaSen multiply the top and bottom by that?
 
Mmhmm.
You can also use my previous hint by expanding $\sin(1-\cos(x))$
 
^That's better
 
@BalarkaSen That looks dubious. How would two points go missing?
 
@Nick Thanks :)
 
@DanielFischer It's three points, sorry. It's because a points goes missing when biholomorphically mapping $\Bbb C$ to $\Bbb P^1$ by $z \mapsto 1/z$
And $w^3 = z$ has three copies of C in it.
 
1:48 PM
@BalarkaSen yes :) il expand and try it now :) thanks :)
 
@TheArtist: Teach her L'Hosp. Thinking is often a waste of time when it comes to limits.
 
@TheArtist Is she familiar with Taylor?
Otherwise Nick's approach would not be of much help.
 
@user130018: Never mind. So, how are you my friend
@BalarkaSen: Taylor Swift, perhaps.
 
$$\lim_{x\to 0} \; \frac{\sin(1-\cos(x))}{x} = \lim_{x \to 0} \; \frac{\sin(1-\cos(x))}{1-\cos(x)} \cdot \frac{1-\cos(x)}{x}$$
For the other factor, you need Taylor of $\cos$
 
@Nick I can teach :) but the problem is thsts not expected ...because it's her assignment, since she hasn't been taught that by profs...so they expect students to do without it...Atleast for now
 
1:50 PM
or at least I don't know any other way to do it.
 
@BalarkaSen thank you very much :)
 
What should I wear as a Halloween costume? I don't have a @Finn hoodie
 
@Alizter see this one (it's about your concern in one of your comments)
0
A: Finding the closed form of $\int_0^1 \frac{(1-x+x\log(x))\operatorname{Li_3(x)}}{(x-1) x \log(x)} \ dx$

Chris's sisThanks to @David H's comment I got that $$\int_0^1 \frac{(1-x+x\log(x))\operatorname{Li_3(x)}}{(x-1) x \log(x)} \ dx=\frac{5}{4}\zeta(4)-\gamma \zeta(3)+\zeta'(3)$$ that is proving to be numerically correct.

 
@BalarkaSen Over $\mathbb{C}\setminus \{0\}$, the Riemann surface is a cylinder, or a punctured plane. On one end of the cylinder, one glues $0$, on the other end $\infty$. If you leave off $\infty$, I don't see how you can get something that is a compact surface minus more than one point. But, all this geometric stuff isn't my forte, so I can't be sure that you're wrong.
 
1:54 PM
@BalarkaSen: There is an easier way to evaluate the second guy ($\lim_{x\to 0}\frac{1 - \cos x}{x}$) using plain old trigonometry. We don't need no Taylor :D
 
Oh, fair enough, @Nick.
wait @Nick. I am not convinced.
what is the trigonometry way?
 
wait till I type. I'm using a blackberry
 
I'm using a Samsung
 
can one of you explain how to convert an object in cartesian coordinates to cylindrical ones? I've having a lot of trouble and can't find good resources on it
 
@DanielFischer Where are you even getting the cylinder?
$w^3 = z$ clearly got three sheets. It's some fancy connection of three copies of P^1s.
 
1:59 PM
my problem specifically is this:
Use cylindrical coordinates to find the volume of the prism whose base is the triangle in the xy-plane given by y = 0, x = 1, and y = $\frac{7}{2} x$, and whose top is given by z = 8 - y
 
@BalarkaSen $z \mapsto z^3$ on the punctured plane.
 

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