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12:24 AM
How do you calculate the frequency from component intensities (660nm, 430nm, 700nm) (what those light-colors add to), and vice versa? Wiki article would be great!
 
Can anyone help me with Sipser page 132?
 
Oh actually, it might not be. T_T
 
Thanx
 
12:45 AM
I've got a quick question.
For this Venn diagram. Are the two statements (below) the same to describe the shaded region?
$(B-A) \cap C$
$(B \cap C) - A$
to describe *when describing
 
 
2 hours later…
2:26 AM
@Khallil Yes, they are both the shaded area.
 
Thanks, @JasperLoy!
What time is it where you are?
 
It is 10.27 am.
 
So what's the "meaning of life" article all about?
 
2:51 AM
Oh, good morning! It's 03:51 where I am, @JasperLoy.
 
 
1 hour later…
3:55 AM
@exTremity i'm not sure, no doubt blue could explain it, but I think it's pointing out an unexpected coincidence between the coefficients of Klein's j-invariant and Ramanujan's tau function, in the same spirit of the "coincidence" leading to Moonshine theory. (moonshine is a (deep, real) relationship between the former coefficients and the dimensions of irr. reps. of the monster group.) The "meaning of life" bit looks like a joke reference to the Hitchhiker's guide since the number 42 pops up.
2
not qualified to tell if it's meant to point to serious math, or if it's all just good fun tongue-in-cheek silliness.
 
4:14 AM
What time is it where you are, @r9m?
Is it about 08:45?
 
4:45 AM
Everything feels so much more serene right after sunrise.
Indexed sets are cool, @BalarkaSen. Thanks for pushing me into set theory. ^_^
 
@AndrewG. Thanks!
 
5:25 AM
Hey, @skullpatrol!
 
Hi :-)
And bye
Gotta run...
 
Me too!
See ya later, @skullpatrol. ^_^
 
Later pal
 
5:57 AM
@eXtremiity they calculated some stuff that turned out to be 42
 
Greetings
@r9m Welcome back! Why so late? :-)
 
hello sports fans
 
Hi Mike Miller
 
6:34 AM
Yo, wazzup?
 
 
2 hours later…
8:38 AM
@r9m Thanks. I was excited when I that idea crossed my mind.
@Khallil Since $X-Y=X\cap Y^C$, you can use associativity of $\cap$ with $A^C\cap B\cap C$ to get $(B\cap C)\cap A^C=(B\cap C)-A$ or $(B\cap A^C)\cap C=(B-A)\cap C$
 
8:52 AM
Find the limit
$$\lim_{x\to 1^{-}}\left(2\int_{0}^{x}\dfrac{\ln{(1-t)}\ln^2{(1+t)}}{1-t}dt-2\ln{2}\ln{(1-x)}
\int_{0}^{x}\dfrac{\ln{(1+t)}}{1-t}dt-\left(\int_{0}^{x}\dfrac{\ln{(1+t)}}{1-t}dt\right)^2\right)$$
@Chris'ssis
 
@chinamath Don't take it personally, but your questions are for kids
 
No,I have meet this problem.....I don't have solve it.
so I ask you it..
 
@chinamath Roughly speaking, each integral can be expressed in terms of polylogarithm
 
@chris's we all start off as kids when learning anything :-)
 
9:07 AM
@skullpatrol Yeah, you're right. @chinamath is just at the beginning. :D
 
I know this reslut,But is not usefull to solve my question:math.stackexchange.com/questions/265981/…
 
@chinamath I know that integral. See that one guy there gave the correct answer - Gilles.J.
 
@Chris'ssis. Arrogant.
12
 
@eXtremiity No, I was kidding. But you see me arrogant because you wanna see me like that.
@chinamath I'd suggest to bring that integral in 2 dimensions and then you'll get that closed form. It's not easy, it's a lot of work to do.
 
I think this hard
 
9:18 AM
@chinamath Well, I did this for $$\int_0^1 \frac{\log(1+x)^2}{x} \ dx$$ and got a very nice solution.
 
This problem is from when I want prove this integral math.stackexchange.com/questions/805298/…
 
@chinamath working in more variables can be extremely useful.
@chinamath Yeah, I got your point, but as I mentioned, using the mutivariables is extremely useful.
 
I know you don't solve other people problem,so I post it ask other math ,Thank you: math.stackexchange.com/questions/907521/…
 
May I know who starred that message with "Arrogant"?
 
It's you!
 
9:28 AM
@chinamath The problem is that in the past I posted in chat a question and asked you not to post it on main, but you did it, you showed me you didn't care my opinion. Now you want help for limits.
 
@Chris'ssis Not me, obviously, I just came here. Seems like 2 users starred it.
 
@BalarkaSen I know ...
 
BTW, I have a question. Is there any condition for having two continued fractions to be equal? i.e., any computationally useful stuff that can identify one with another?
@blue
 
simple continued fraction representations are unique, otherwise dunno
 
@blue by simple you mean 1/stuff + 1/stuff + 1/stuff + stuffs, right?
i forgot all the names
 
9:35 AM
mmhmm
 
drats. mine are nonsimple.
 
you could bound $[a_1,\cdots,a_r,\cdots]$ above or below by $[a_1,\cdots,a_r]$ based on whether $r$ is even or odd
 
me knows. that wouldn't help here.
 
blah, I need notation for both nums and denoms
 
@blue just use the cfrac stuffs. take a but latex, but is explicit.
*bit
hmm.
gives up. i gotta go.
 
9:42 AM
Arrogant? Well, I don' t think you'll ever read my questions here. :-) Maybe in another life.
 
r9m
@Khallil it was 9:44 am :P lol
 
Hey @r9m :). Hows Naruto?
 
@blue I don't think simple ones are unique either
 
@BalarkaSen For irrationals they are. For rationals there are precisely two representatives.
 
@MikeMiller Not convinced.
 
9:56 AM
Don't care.
It's true.
 
LEL, OK.
 
if $x=[a_0,a_1,\cdots]$ then $a_0=\lfloor x\rfloor$ and $[a_1,\cdots]=1/(x-a_0)$; rinse and repeat. (assuming everything's positive)
 
So if $[a_0, a_1 , \cdots ] = [b_0, b_1, \cdots]$ then $a_i = b_i$.
Right?
 
as long as those are infinite, yes
 
i am considering about irrationals anyway.
@blue can all periodic continued fractions be transformed into simple ones?
 
r9m
9:59 AM
@eXtremiity Hey :) ... I'm most excited about the forecoming Hashirama vs Madara battles :D .. apart from that its all boring atm :P
 
in the sense that it represents a real number...
 
r9m
@Chris'ssis :D was caught in local traffic called exams :P
 
@r9m. I was about to say that Naruto has been brilliant! But that's because I fast forward all the boring bits :p. I have to agree with you. Last episode was so bad. I skipped through 95% of it.
 
r9m
@eXtremiity ya ,, similar experience here too :|
 
And I was so excited.....
Suddenly every can fight >_>.
 
10:02 AM
@MikeM @blue say $$-4 + \cfrac{x}{-4 + \cfrac{x}{-4 + \cfrac{x}{-4 + \cdots}}}$$. Multiplying above and below by $1/x$ one gets $$-4 + \cfrac{1}{-4/x + \cfrac1{-4 + \cfrac{x}{4 + \cdots}}}$$. Continuing in this fashion one gets the simple one $[-4, -4/x, -4, -4/x, -4, -4/x, \cdots]$
Am I doing it right?
 
when one speaks of continued fractions, the terms are meant to be positive integers
so that's silly unless $x \mid 4$
 
i have no problem if terms are rational
 
then you're not getting to a simple continued fraction
 
So if $[a_0, a_1 , \cdots ] = [b_0, b_1, \cdots]$ for rational $a_i, b_i$, then it might or might not be true that $a_i = b_i$?
 
yes
 
10:05 AM
drats
 
I ate 20 slices of raw salmon yesterday.
 
r9m
@robjohn :D
 
Huy
@JasperLoy: Eww.
Why would you do that?
 
@Huy It is called sashimi, lol.
 
Huy
@JasperLoy: I wouldn't know, I don't eat fish.
 
10:11 AM
@Huy Are you vegetarian?
 
Huy
@JasperLoy: No, I just don't like the smell and taste of fish and seafood.
 
@Huy Fish is certainly better than pork.
 
Huy
@JasperLoy: That's just like your opinion.
 
r9m
@eXtremiity the thing is ... there is only 5-15% of the content interesting .. the episodes are just 22mins approx and over that 7 days($7\times 24 \times 60$ mins) of waiting after each episode .. I'd say that's a poor distribution of fun/exciting stuff .. almost approaches dirac-delta at places :P
 
@Huy Everything I say is my opinion. What else could it be?
 
Huy
10:12 AM
@JasperLoy: Mine.
@JasperLoy: I enjoy most other meat, except for more exotic things like snails or frogs.
 
@Huy I'm with you on this one.
 
Huy
I'm glad I'm not all by myself.
 
I am trying to lose 10 kg, from 70 kg to 60 kg.
Maybe it is my meds making me fat.
 
Huy
@JasperLoy: I am trying to gain 10 kg.
How tall are you?
 
1.65 m
 
Huy
10:17 AM
So about the same as I am.
@JasperLoy: If only you could give me your excess amount of weight.
 
I want to be rid of my mental illness too.
 
Huy
Is it possible?
 
It is difficult.
 
Huy
I wish you good luck, then.
@DanielFischer: Good day.
 
Good day.
Grüezi.
 
Huy
10:21 AM
Very good.
:D
 
Greetings, @DanielFischer
 
Huy
@DanielFischer: Where did you learn that?
 
Hi @Mike.
 
@r9m. Hahah, well said ^_^.
 
@Huy A bit of Schwyzerdütsch transpires.
 
10:22 AM
When the first hokage gave his throwback stories, the episodes were great :).
 
Huy
@DanielFischer: Chuchichäschtli?
 
@Huy I'm not sure whether the first part means Kuchen or Kekse, Chäschtli is evidently "Kästchen", which would probably be translated as Schachtel to German German.
 
Huy
@DanielFischer: It means "Küchen".
 
r9m
@eXtremiity yas !! that was really gr8 :)
 
Huy
@DanielFischer: Kästchen is used more in the sense of a cupboard. It is the typical word a non-Swiss person learns first in Switzerland.
@DanielFischer: Kuchen would be "Chueche" and Kekse "Guetzli", at least in the dialect of Zurich.
 
10:25 AM
When I was watching Naruto (not Naruto Shippuden), I really wanted Sakura to die. After the last episode, I remember why. She's so annoying.
I always thought she wrecked the awesomeness between Naruto and Sasuke.
 
@Huy I've mostly been in the francophone parts. The first word I learned was "huitante" - the Hotel clerk noticed my bewilderment and translated it himself: quatre-vingt.
 
Huy
@DanielFischer: Yes, some people do say huitante. Also septante, iirc.
@DanielFischer: But why have you only been there? Zurich is much more beautiful and has much more to offer. ^_^'
 
@Huy Not many mountains in Zürich, as far as I know.
 
Huy
@DanielFischer: You came to Switzerland because of the mountains, then?
 
r9m
@eXtremiity the story rolls subtly around her emotions/ego .. the sasuke chase arc was after all bcoz of her request to Naruto to bring her crush cback to the village :P
 
10:30 AM
@Huy Mostly.
 
Hmm, yes - that's right. Sakura's request was predominately the reason for the chase.
Man when Sasuke came back and they all reunited - that was so cool!
 
Huy
@DanielFischer: Did you at least go skiing or snowboarding?
 
"I want to be Hokage >_>". Major lol ^^.
 
r9m
@eXtremiity but at times however I feel like she's a gigantic waste of screen time :P
 
@Huy No, just - what's it called - faire des randonnees.
 
r9m
10:31 AM
@eXtremiity xD
 
Gigantic is an understatement.
She's just not cool.
At all.
 
Huy
@DanielFischer: I see. I'm not very fond of hiking.
 
r9m
@eXtremiity Kishi trolls her every now and then .. :P maybe that's her roll :P
 
@r9m. How cool would it be to create your own anime - own story line and what not _.
 
r9m
@eXtremiity idk .. :) but I guess it would be a grand experience :D
 
10:36 AM
@r9m. Forgetting about the success of it all - just creating events in your mind, playing them out as they should. If you forget about all the garbage Naruto (the show) has to offer, it is actually a piece of genius in my opinion.
From story line to story line. I think its incredible. I enjoy the philosophical opinions of certain characters.
 
r9m
@eXtremiity true .. :) I still think the Zabuza episodes in the beginning of Naruto are still the best .. it was a vivid portrayal of the convictions and contradictions of a shinobi life (human life too perhaps ..) & not to mention the awesome actions and ever raising tension along the lines !! :D
 
@r9m. Agreed ^.^!
 
r9m
Kish delivered a lot in those 3-4 episodes .. its perhaps the most condensed form of the entire theme line .. every episode from then on has been only a dilution of that intensity .. :) (except of course the Hashirama-Madara sequence .. which is battle of the $\alpha+$ and far above the ordinary !! :D .. )
 
10:55 AM
:D !!
It is an exciting period.
 
r9m
@eXtremiity :D
 
anime
duh
 
@DanielFischer Do you know a closed subset of the plane that's not locally contractible?
 
@MikeMiller "Locally contractible" means every point has a neighbourhood that is contractible? Or a neighbourhood basis of contractible sets?
 
To me it means the latter.
Nevermind.
For some reason I discarded the comb.
 
11:10 AM
@MikeMiller Something Hawaiian, I'd think, $$\bigcup_{n\in\mathbb{N}\setminus \{0\}} \left\{ z : \left\lvert z - \tfrac{1}{2n}\right\rvert = \tfrac{1}{2n}\right\}.$$
 
Hawaiian works too.
Thanks
 
Huy
@DanielFischer: Let $u \in W^{1,p}(I)$ for some interval $I$ and w.l.o.g. $|I| \leq 1$. We know $$|u(x)-u(x_0)| \leq \int_I |u'(t)| \, \mathrm dt = \| u' \|_{L^1}.$$ Thus, after averaging w.r.t. $x_0 \in I$ we find $$\| u \|_{L^\infty} \leq |I|^{-1} \int_I |u(x_0)| \, \mathrm dx + \| u' \|_{L^1}.$$ What just happened in the last step?
 
@Huy The first inequality gives you $\lVert u\rVert_{L^\infty} \leqslant \lvert u(x_0)\rvert + \lVert u'\rVert_{L^1}$ for arbitrary $x_0\in I$. Then you just replace the arbitrary $\lvert u(x_0)\rvert$ with the average. (Consider an $x_0$ such that $\lvert u(x_0)\rvert = \min \{ \lvert u(x)\rvert : x\in I\}$ to see that it's true.)
 
Huy
@DanielFischer: If I look at the first inequality and add $|u(x_0)|$ to both sides, I can get $|u(x)| \leq |u(x_0)| + \| u' \|_{L^1}$ by the triangle inequality. Then you suggest taking the supremum on both sides, is that correct?
 
11:27 AM
The right hand side is independent of $x$, so you take the supremum only on the left. Then you take the infimum (w.r.t $x_0$) on the right, then replace the infimum with the average.
 
wat
 
Huy
@DanielFischer: I see, thanks.
 
RH is related to l-adic cohomologies and etale fundamental groups?
who knew !
 
One proves the Weil conjectures (including the "Riemann Hypothesis for curves") using those. This is probably what you're thinking of.
 
looks interesting. but far ahead of where i am. jerks head to shake these stuffs off
never knew that there was a RH for algebraic curves
@MikeMiller like, you're saying that one could, say, determine the zeros of the L-function attached to some elliptic curve using those?
 
looks greek to me
O_o
 
Huy
@DanielFischer: I'm confused. Isn't $|I|^{-1} \int_I |u(x_0)| \, \mathrm dx = |u(x_0)|$ since the integrand doesn't depend on $x$?
 
@Huy Yep. It's probably meant to be $\int_I \lvert u(x_0)\rvert\,dx_0$.
 
Huy
@DanielFischer: That's what I thought too. I guess a typing error.
 
So guess I.
 
Huy
12:04 PM
Good day, @TedShifrin.
 
Greetings @Huy @DanielF
 
Morning, @Ted.
 
I give up on greetings. There are too many people going in and out of chat, lol.
 
Ungreeting @Jasper ... I'm about to disappear
 
@TedShifrin Did you give Pedro any of your books?
 
12:07 PM
He said so, yes.
 
The past 5 years, I have dropped so much hair.
It's all the stress from my mental problems.
 
@TedShifrin Morning
 
Hi @nablablah, long time.
 
12:48 PM
Hello hello hello
 
In case you haven't seen it yet
 
Huy
1:01 PM
@DanielFischer: For bounded $\Omega$, $1 \leq p < q \leq \infty$ implies $L^q(\Omega) \subseteq L^p(\Omega)$. Can one say something specific about unbounded $\Omega$?
 
@Huy The inclusion holds if the measure of $\Omega$ is finite. If the measure is infinite, neither is included in the other for $p\neq q$ (I'm assuming we speak of open $\Omega\subset \mathbb{R}^n$ and the Lebesgue measure, for $\ell^p(\mathbb{N})$ for example, we have the inclusions in the other direction).
 
Huy
Yes, I meant open $\Omega \subset \mathbb{R}^n$.
 
What happened with @chris's sis ??
 
Huy
@Hippalectryon: eXtremiity called him arrogant and soon after he ragequit, methinks.
 
I hope he does come back, i'll be lonely otherwise :c
 
Huy
1:13 PM
Wow, so it actually was a ragequit.
I don't miss him. :)
 
I do :/
 
@Hippalectryon Her
@Huy her
 
Huy
Him.
There are only guys on the internet.
Everyone knows that.
 
@JasperLoy Oh sorry I always forget xD
 
@Huy No, that is nonsense.
 
1:14 PM
I have around 50 images of problems he posted in chat :D
For when I have learned more :c I'm currently totally unable to solve them
 
I wanted to exchange email with her, but she declined.
I have about 20 SE user emails now...
 
Even if she quits (which would be really unfortunate :c ), I hope she still notifies me when her books comes out if it does
 
Huy
Congratulations.
 
1:27 PM
@Hippalectryon Well, to be honest, Chris'sis is a bit too arrogant. Infact, I want to remove the bit, she is arrogant.
...though I was not aware of this development :O ..
 
Huy
@Sawarnik: Some guy (I think china math) came into the chat and asked Chris' sis for help with some limit/integral. She replied "Don't take it personally, but your questions are for kids".
 
sigh alright what drama is here now
 
it started here
5 hours ago, by Chris's sis
@chinamath Don't take it personally, but your questions are for kids
How can anyone not take that^ personally?
 
Huy
Well, she did say "don't take it personally", that's how. /s
 
Well, to me it seems more like teasing
 
1:35 PM
@AlexanderGruber HELLO
 
I wouldn't really care if she told me that? I know she far far exceeds my abilities in this field
 
Huy
@Hippalectryon: Well, sure, if it's a friend. But not if it's someone else genuinly asking for help.
 
and then to say "I was kidding"?
 
@Huy That's stoopid.
"Don't take it personally... your ...."
 
@PedroTamaroff hey man, are you still in america?
 
Huy
1:36 PM
@PedroTamaroff: Are you aware of the symbol "/s"? It stands for sarcasm.
 
@AlexanderGruber I left on Wednesday. =(
 
It seems that there were previous facts
 
@Huy Oh, sorry then.
You're too internetz savvy for me.
 
Huy
@Hippalectryon: It doesn't make her statement any less arrogant. If someone's being a dick to me doesn't justify me doing the same to them.
 
@Huy At any rate, don't make it a big deal.
 
1:37 PM
@Huy I was referring to 'But not if it's someone else genuinly asking for help.
 
It's some stranger on the web.
 
@Huy i agree with that.
 
Huy
@Hippalectryon: Well, the china math guy was asking for help at this point. He might have some bad history with Chris' sis but he did normally ask for help.
 
which is why i do not like that everyone seems to be trying to publicly shame her for what to me seems like light teasing, or at most one off color comment
 
@AlexanderGruber I saw your post on cyclotomic polynomials. Nice pictures.
 
1:38 PM
:-)
 
Huy
Chris'sis could have just ignored china math instead of saying "your questions are for kids" - in my opinion.
 
@PedroTamaroff thanks. I'm working on getting it set up in Python so I can get some more high res stuff
 
One has to learn deal with it.
 
Huy
@PedroTamaroff: I don't really care about her because we don't really talk to each other but I can see why people would think of her as arrogant.
And what she replied to china math definitely qualifies as an arrogant statement - imo.
 
@Huy Dunno. Last time I talked to him he dropped the same line and I was like "sheesh you don't have to be an ass just answer the question."
 
Huy
1:40 PM
And then reacting by leaving the website is just childish.
 
4 hours ago, by Chris's sis
@eXtremiity No, I was kidding. But you see me arrogant because you wanna see me like that.
 
@Huy Chris ragequitted?
 
28 mins ago, by Hippalectryon
http://math.stackexchange.com/users/32016/chriss-sis his new description :/
 
@Huy Oh, what a tragedy.
 
Huy
1:41 PM
I know. I'm heart-broken.
 
@Huy What have you been studying lately?
 
Huy
@PedroTamaroff: I have an exam on Tuesday about functional analysis, mostly Sobolev spaces, their regularity and Schauder theory, so just kids' stuff to be honest. :P
What about you, @PedroTamaroff?
 
@Huy I'm trying to study commutative algebra at the moment.
 
Huy
Just trying?
 
@Huy It's just a figure of speech, I guess.
=)
 
Huy
1:45 PM
Good, I was worried.
How would you summarise what you are studying in few sentences for another maths major who knows nothing about commutative algebra? I did take an abstract algebra class but I don't know if it has anything to do with it.
 
commutative algebra is abstract algebra with all the joy removed
 
Huy
What joy in abstract algebra?
 
@AlexanderGruber LEL
@Huy Abstract algebra studies commutative rings. But I guess you guessed that?
 
Huy
@PedroTamaroff: Yes, I would have guessed that.
So what's interesting about commutative rings?
 
@Huy Some things are interesting. Like studying the poset of ideals of the ring.
 
Huy
1:49 PM
@PedroTamaroff: Poset = ?
 
Partially ordered set.
Or the set of prime ideals, which one can give a topology, related to geometrical ideas.
 
Huy
I see. Can you give me tell me about any applications? If I have some commutative ring and I know something about the poset of its ideals?
 
@Huy do you mean real world applications or applications within mathematics?
 
Huy
@AlexanderGruber: Both.
 
only real world applications i know of for commutative algebra are in cryptography
computing groebner basis and stuff like that
 
Huy
1:53 PM
And within mathematics but extended to other areas?
 
oh gosh, there's lots of stuff
 
Huy
Something to impress me?
 
well i'm not really a proponent of CA so i'm not the best person to ask, but without it we wouldn't have algebraic geometry, category theory, scheme theory, any of that stuff
 
Huy
@AlexanderGruber: I don't really know anything about all these areas. :D
 
you're an analyst yea?
 
Huy
1:57 PM
@AlexanderGruber: I wouldn't call myself that.
@AlexanderGruber: I am interested in mathematical physics. I think physicist tend to not know much algebra so it's mostly analytic mathematics.
 
@Huy okay, so the foundations of string theory can be expressed in terms of commutative algebra
 
Huy
I see. I don't know much about string theory yet either. But I will at some point, I hope.
 
I know that string theory is about strings, lol.
 

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