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18:00
@AlecTeal there are formulas for lunar exposures that use the focal ratio and the phase of the moon that give decent exposure times.
I sent my work (well, a part of my work to some publisher). Waiting for an answer from them in the next period of time.
@StanShunpike Think so
Found a question along what I have been asking myself for a few days now. No answer for higher-than-2 forms. Hmm. It might actually be difficult. :-)
@Chris'ssis Good luck!
@robjohn Thanks.
I have a mix of thoughts in mind about what to do after that (after publishing my book). I still think of leaving math once and for all.
18:03
@ccorn Note the comment on the answer.
@robjohn I didn't even have the proper equipment
@MikeMiller Yes, that's reassuring... so I have to look at the specialized problem, not the general one. Sigh.
Hey everyone?
Can anyone give a list of important topics in complex analysis one should have a good grasp of before starting to read about algebraic curves and Riemann surfaces?
In particular, are $H^p$ spaces important?
no, I doubt you'll see Hardy spaces in any introductory accounts of Riemann surfaces.
there's usually some functional analysis that shows up when proving Riemann-Roch; but you can cross that bridge when you come to it
i guess modular functions and monodromy are important thought right?
though*
18:07
Most good books on Riemann surfaces are self-contained, other than assuming a first course in complex analysis. If it wants to use those, it will likely talk about them.
Ah great I want to start reading from Rick Miranda's "algebraic curves and riemann surfaces" this summer but i wasn't sure about the prerequisites. Thanks!
I'm so full of angry seeing the way some build their success and pretty disappointed at the same time.
@Saal Take a look at the preface/introduction. It should tell you what it expects you to know, roughly.
@AlecTeal Proper equipment is pretty much required for good astrophotos. I don't use my largest scope right now because I don't have a mount that is sufficient.
Anyway, I leave math after that. I'll feel much much better.
18:16
@Chris'ssis why would you do that? You build up an expertise and then ignore it?
@Chris'ssis :/ noooooo
@SaalHardali Be careful with modular functions. At least if you are the Sherlock Holmes type, habitually searching the darkness for the few identities that might be clues to your solution. In the modular realm, identities are the rule, not the exception. Blinding lights! These might burn out your brain. Wear sunglasses. (Take my userpic as a warning.)
any chemistry people?
@AGoogler me, a bit
@Hippalectryon Why can I replace br and cl in sn2 reactions?
isn't I- more stable than either cl- or br-?
18:22
Stable ? Define stable
@robjohn Perhaps I should consider that more than other things. I like math, that's true.
like , in acid base reactions , the logic is that HCL + I- ----> HI + Cl- doesn't take place because cl- is less stable than I-
why is it different here?
Br,Cl,I can be replaced by each other because they're all organomegnesium compounds. A SN will work better with I than BR than Cl though
organomegnesium?
18:24
Urm in what context did you see sn2s if you haven't talked about organomegnesiums ?
but we're not using grignard reagents
Well ok let's just call them nucelophiles
First of all I'd get back on what you were saying about HCL+I- not making HI+Cl-
okay
i just started to study organic in high school
The reason why it's not happening is not just because of the relative stability of I- and Cl-, but because (HCl and I-) is more stable than (HI+Cl-). If HI wwas highly unstable for instance, the reaction couldn't occur either.
Now i'll get back to the main question
A sn2 requires a nucleophile. I,Cl, Br are all nucleophiles and can take part in sn2 s. However, it's easier energy-wise to have an Sn2 with I than with Br, with Br than with Cl. That is because I is more polarisable.
easier with I as a nucleophile or electrophile?
18:28
I is nucleophile. It's on the far right of the periodic table.
but isn't that only true in polar protic solvents
in polar aprotic solvents , isn't cl- a better nuc. than I-?
that's what i learned
Ok I'd like to make sure of one thing : what did you mean when you said 'Why can I replace br and cl in sn2 reactions?' ? are you asking why a sn2 which uses Br can also be done using Cl, or why Br-+(...)Cl -> (...)Br +Cl- occurs ?
O_o I ask 'Is it A or B' and you answer yes lol
in my opinion it shouldn't occur because br- is more stable than cl-
wait a min
18:32
@AGoogler Linux's better...
i think it confused you that i capitalized the "I" , it means iodine not me
@Ramanewbie what?
@AGoogler Use linux, not MacOs ! -_-
@Hippalectryon i meant why can iodine replace chlorine in sn2 reactions
@AGoogler Ok I see
@Ramanewbie i don't use macos!
18:34
@AGoogler But... Your account image is MacOs logo !
@Ramanewbie lol yeah but i don't use it
@AGoogler What do you use
@Ramanewbie windows
@AGoogler better than MacOs
@Ramanewbie i'd like to try linux though , which one would you recommend?
18:35
@AGoogler I think Ubuntu, it's the most common one.
@AGoogler don't listen to him q_q
@hippa but I'm right -_-
i was going to try arch linux
@hippa I've made an effort not using it for a time... Because it woudn't install !
@hippa only in Virtual Box I mean
18:38
@AGoogler Why would Cl- be more nucleophile than I- ?
@AGoogler And in what solvent are you working ?
the logic in polar aprotic solvent sis that a better base is better nucleophile so Cl->I- however in polar protic solvents its the opposite because cl engages in hydrogen bonding with solvent , decreasing its effectivity
@Hippalectryon acetone which is polar aprotic
I know modules are a generalization of vector spaces. What is the relation of affine spaces to vector spaces?
@robjohn here is an amusing question I created today
$$\Re\left \{1-\frac{1}{1!}-\frac{i(i-1)}{2!}+ \frac{(i-1)(i-2)}{3!}+ \frac{i(i-1)(i-2)(i-3)}{4!}- \cdots \right \}$$ it's meant for fun. Thinking to add it to my book too.
how to see latex?
18:42
@Chris'ssis I have to go to the vets. That is interesting. I will look when I get back. I've been dealing with MSE crap this morning. Sorry for being absent.
@robjohn it will make you laugh. OK. :-)
@AGoogler Where did you see the reaction above in acetone ?
@Hippalectryon in a book
I'm OUT too for 30 min or so.
@AGoogler Oh yeah I see
give me a sec
18:47
sure
@Hippalectryon Before going, I wanna say that as regards my last creations it is possible that even Euler and Ramanujan working together to be in trouble with them.
I'm out now.
this page for example has it - www2.chemistry.msu.edu/faculty/reusch/virttxtjml/alhalrx1.htm see the solvent effects section
@AGoogler Are you sure it's a Sn2 and not a Sn1 ?
I have offered a bounty for that question now. (Take your time, it seems nontrivial.)
18:52
@Hippalectryon in my book , it is a reaction where NaI is added to a compound containing bromine in acetone
@Hippalectryon yes , the answer has inversion of stereochemistry
@Hippalectryon also sorry for replying to that old comment , i was scrolled up and thought you asked it again
@Hippalectryon also i guess sn1 reactions don't really happen in aprotic solvents such has acetone , do they?
indeed usually they don't
@Chris'ssis Okay, this is where I'm going to draw the line. You're vastly underestimating the great minds of the past, and going around comparing yourself to them will get you nowhere. I know this is rich coming from me, but I think you need to learn to show some more humility.
If this comment leads to me being suspended from the chat for a bit, then so be it. I just said what I felt should've been said.
@AGoogler Finkelstein reaction then
@Hippalectryon i see , but why does it happen?
@Hippalectryon " since KCl and KBr are insoluble in acetone and are consequently removed from the equilibrium:" is that the reason?
That's one of the reasons at least
the equilibrium is driven forward by the poor solubility of the salt formed
That's probably it
19:01
@Hippalectryon i found this page - organic-chemistry.org/namedreactions/finkelstein-reaction.shtm it says you can replace any halid by any other halide
@Hippalectryon oh well then that was a quite tricky question
Well of course you 'can' since it's an equillibrum... but for instance if you try to replace F by I, the yield will be extremely small
Near to 0
i see
any expert about computation theory is here ? can I talk ?
@Hippalectryon how dis you quickly found out the name of reaction? i'm impressed!
@AGoogler It can be catalyzed though
19:03
*did find
@AGoogler I studied it a bit :D (I'm a student too)
@Hippalectryon aha , great!
@Hippalectryon, thanks
I ran into a problem
in one of my note
says
@AliMovagher oopps wrong ping :c
19:04
@AliMovagher Ask first, people will see and hopefully answer :-)
K={x | x $ \in W_x $ } is not an index set, why?
don't ask to ask , beg and grovel to ask!
(that was the topic of a chemistry irc channel)
Who can help me ?
19:06
What is $W_x$ ?
I say
W_x is the set of inputs for which the program encoded by x halts
i think this is halting set.
@Hippalectryon Thanks a lot by the way
@evinda or @DanielFischer might be able to answer when they're here, @AliMovagher
@AGoogler :-)
@DanielFischer, would you please help me?
@AliMovagher Not sure whether I can. What is an "index set" in this context?
19:12
@StanShunpike Affine spaces are like vector spaces without a preferred origin
index set is a set of all indices of some family of computable [partial] functions/computably enumerable sets.
@DanielFischer, I SAY. THANKS,
@AliMovagher So $K$ contains codes for programs that halt when given their code as input?
YEAH, K is a halting set.
@ccorn.
@AliMovagher Ah, sorry. Computability is outside my ken.
who can help me @DanielFischer :)?
19:14
I designed an adding machine,once. Never again.
@AliMovagher I don't know. Perhaps you should ask on cs.se?
I have encountered GCC devel sources that were not in $K$
(hangs after bootstrapping)
19:30
@teadawg1337 I love Ramanujan and Euler, I don't compare to them in that comment although I have no problem to say that I wanna become like Ramanujan or far beyond, but for the fact that my last creations use a certain technique (pretty complicated) I also developed, it seems hard even for a very good mathematician to easily get an answer there in my opinion. I cannot show humility anymore, there is no need for that.
@teadawg1337 I understand your comment. No problem.
I considered the positive part of it.
@Chris'ssis it looks like something that can be solved with taylor series to me , is it so? i only know a tiny bit of real variable calculus so forgive me if i'm speaking nonsense
@AGoogler I don't know what you refer to.
@Chris'ssis you problem, can it be solved by a taylor series approach?
i meant your problem
@AGoogler I didn't try it. I used something simpler.
19:36
@AGoogler But, yes, it works to use Taylor series.
@Chris'ssis To me, you seem to be coming off as arrogant. In my opinion, showing some humility (maybe even feigning humility) will get you farther than acting like you're better than everyone else.
Maybe it's just because I'm in a super crappy mood today, I dunno.
@Chris'ssis is the answer 0.42882900629436784932265200709733549961174774695121920952369...?
@teadawg1337 I prefer to show respect, not humility.
basically real part of (1+i)^i
@AGoogler Yeap. This is not one of the problems I was referring above.
19:44
oh
@Chris'ssis which was it?
:20663742 This one was for kindergarten. Just for fun.
I have to write up some more proofs. Back a bit later.
@Chris'ssis which problem were you reffering to?
19:56
@AGoogler Oh, some problems I'm going to add to my book.
@Chris'ssis cool , so you're writing a book! what is the book about?
@AGoogler an awesome book
@AGoogler It's a collection of problems coming from personal research mainly about integrals, series and limits.
seems nice , i'm currently studying those topics
@Chris'ssis Did you research to make sure that it is a method that you in fact developed, and hasn't been done before? That's what I do, and I generally end up walking away with a lesser opinion of myself. Perhaps I don't have the resilience to pursue a career in maths, I dunno.
All I know is that I'm in no position to give advice
20:04
@teadawg1337 You never know for sure, I mean 100%. Yeah I did some research, plus my experience, and I found nothing like that so far.
I'm starting to get to that point where the material is becoming more and more scarce, and I guess that implies a higher probability of uniqueness in my work
20:19
@Chris'ssis Just a matter of curiosity ;).
My work involves 1+1=2.
@Hippalectryon Retour de Hippa ?
@Gato @TedShifrin For several days we slumbered... __Now we Riiiiiiise__
@Gato This was also one of the songs loved here. Ah, but it's not a Romanian song ...
tl:dr; I'm back ;D @Gato
20:22
@Chris'ssis Today I lear the game : sapte oaemeni fac o casa cite lemne trepuiesc :p
No problem, I am listening.
@Gato :-))))))))))))))))))
and the 'hora' dance :D @Chris'ssis
@Gato :D
@Gato I like your attitude. You never criticize people, but make them have fun. :-)
@Chris'ssis Sorry about my outburst earlier
@Chris'ssis I really enjoy learning romanian 'culture'.
20:26
@teadawg1337 No pb. Once I was one of the humblest persons I ever knew, and I realized that it's of no good. I only prefer to respect people now.
@Hippalectryon What's up ?
@Gato The sky :3
And the exams soon
is black ?
@Hippalectryon Ah yes, exams. Ready ?
Salut @Hippa @Gato, hi @teadawg
20:29
@TedShifrin Good afternoon.
@Gato Cultura.
Hello @TedShifrin
@Chris'ssis :DD
@teadawg: Because it was raining, a fourth of my differential geometry students skipped class yesterday. I was not pleased.
RAINING???
20:31
Yeah, like, right, like ... :D
Why would anyone skip class just because of a little rain?
Hi Ted, gonna bed in 30 min.
Almost-good-night, @Jasper.
I even went to class when school was closed due to a snowstorm
And the professor was there too lol
And one of them, one of our grad students, had the nerve to waltz up to me at 5 PM yesterday, @teadawg, and innocently ask "What did I miss?" I told him it wasn't my problem.
20:32
@TedShifrin That is crazy
@Gato :D
This is why I'm quitting, @Hippa.
If you're deathly ill, send me an email and explain ... But I've had it with this.
What kind of question is that, though? Did he expect an entire lecture over again on the spot? lol
20:33
I have already decided I won't help the students that skipped in office hours, mr eyeglasses.
Isn't it better to just ask a classmate for notes or something
Yes, that would have been the appropriate thing to do, not to mention a cursory apology.
I skipped many lectures but nobody cared.
CUNY used to kick students out of school if they missed too many classes
I won't skip anymore in future, promise.
20:34
I still remember a calculus student from my first year teaching here who missed one class out of 50 in integral calculus, apologized to me and told me that in the next quarter's class he would miss not a single one and he would get a higher grade. He was right.
The others were left
@Jasper: If someone gets an A and doesn't need my help, I don't care either, although I do like to have class participation. But usually the ones who miss are doing poorly.
I did skip two classes this year though in physics,, I didn't wake up because I didn't hear my alarm clock ring :/
Yeah, @Jasper. I'm an oddity. I do care.
The lectures I skipped were by the bad professors whose lectures I did not understand.
20:35
I've had people sleep through my 11:15 classes... What?
well, I'm sure there are some students who would say that about me, @Jasper, but ...
I'm paranoid of missing classes because I feel like at any given class, the professor might say something super important or something (besides the lecture)
I think the fact that you put up youtube vidoes shows that you are a good teacher already. Also you write good books.
A good teacher gives context and nuances and emphasizes things that you cannot get from a textbook.
@TedShifrin Why is that not surprising hehe | 'Breaking news ! less attendance to classes gives better grades !!'
@Jasper: You don't know anything about my books :D
20:37
Ah yes, but looking at the contents and a few pages is enough, lol.
I have had students, probably like Jasper, who say they cannot learn from lectures and can only learn by reading books.
Many of us are not like that.
Anyhow, @Hippa, il faut que tu étudies :P
I think maybe I am autistic or something, I will go ask my shrink about that.
I think lectures for me are more of an assurance from an authority figure on the topic that what I learned from the textbook is correct because I'm always scared of misunderstanding something I read and learning the material completely incorrectly, but an affirmation from a professor who knows the topic puts me more at ease
For one, I don't really look at people in the eye when I talk.
Shy people do that all the time, @Jasper.
20:40
@TedShifrin I know :-)
mr eyeglasses, I try to give insight and approaches to examples/problems which will help with homework more than the book does ...
@TedShifrin Blind people too :3
But one reason I don't look at people when I talk is because it is hard to focus on what you are trying to say.
I'm diagnosed with Asperger's, @JasperLoy, I wouldn't be surprised if you have some form of autism. If anything, it's a mild case
@Hippa: Sometimes they do look in the general area of your face ...
I've had several students with Asperger's, @teadawg. One in particular is extremely smart and extremely stubborn, has taken 6 classes from me, and gotten grades from C- to A- ... but all should have been B or better. Sigh.
He just refuses to read problems carefully and to give himself enough time to do a good job, insists on his creative approaches even when they fail :(
20:42
He's not called Reynolds by any chance ? :O
But he did ask me a really good question in probability (about the law of large numbers). I had to go off and think for about an hour to answer it and explain it.
Qui ça, @Hippa?
That dude you're talking about. Reminds me of some student I know in America
You know students in America?
Only him. I have no idea where in the US he lives though
Plus a few from chat in here ?
20:44
Yeah, but you know those too
I haven't talked to him for a while though
I haven't seen LeDodo in ages ...
He was here some minutes ago
but he logged in and out
Didn't say a thing
Probably because you were here :P
20:46
@ted Do you get many downvotes on your answers?
I guess I'm a mathematical "savant" of sorts, since I'm slightly above average in every other area.
What strikes me most about autism is how much it varies from person to person
Someone recently targeted me with downvotes, @Jasper, and it's happened once before. Occasionally I deserve them, and I have removed a few answers that were just bad.
@TedShifrin Seriously I hope he still isn't mad at me
I didn't know he was mad at you, @Hippa. What did you do this time?
If you get mad at people for too long, you get mad.
20:47
I prefer to air grievances and not stay angry, but I have a colleague who hasn't spoken to me in over 10 years. And it's basically because he believes I did something I in fact did not do.
But I figure that if I have friends from more than 50 years ago, I can't be that horrible :P
@TedShifrin chat.stackexchange.com/transcript/message/20351338#20351338. I don't even know what I did to take him say that.
Once a girl thought I made prank calls to her at night, which I never did.
I think I was here when that happened, @Hippa. He doesn't like your assumptions any more than you like Chris'ssis's assumptions that you're twice as old.
I don't usually care if people think I did something that I didn't, but it gets really annoying when other people that significantly impact your life begin to believe it and it messes up your life
My friend suggested that I made those calls to her because of some things I said, so it's his fault.
20:50
Yup, mr eyeglasses. It's really not good.
@TedShifrin He's got an X's picture on his profile though and a French name :/ how was I supposed to not make that assumption
I got many such assumptions when I first joined MSE...
Although I do stalk people, I do everything openly and tell no lies.
But I think you persisted in discussing/insisting on it, @Hippa, after he'd earlier asked you not to.
@TedShifrin It's the first time I think I talked to him
20:52
isn't "stalk" and "openly" a contradiction, @Jasper?
That's not true, @Hippa. Shortly after I started talking with you both almost a year ago you guys were talking.
Oh, I mean I find out info about people online, but I don't hack into anything that is meant to be secret.
@JasperLoy Wha...... What??
Isn't that just doing a background check?
If you put info about yourself online, it's not my fault that I look it up.
Only certified people are supposed to do background checks ?
20:53
@TedShifrin Ugh I don't remember :/
I'm pretty sure, @Hippa. I know I'm old, but my memory is still mostly in tact.
Of course, he had a different name back then.
I remember when I first saw Ted Shifrin in this chat, I thought he was a celebrity because my friend had shown me his differential geometry textbook the year before and he told me it was a famous textbook
@JasperLoy It's common decency to respect the privacy of others, though...
@teadawg1337 Yes, but I am not hacking into anything.
mr eyeglasses, far from celebrity.
@teadawg: Sometimes we all use Facebook and google to look up people we've run into.
20:56
@TedShifrin More like godly status
Ah, shaddup, @Jasper.
@TedShifrin Well that would explain why I can't remember that
morning.
@Hippa: You change names more than anyone else here (except Jasper and mr eyeglasses), so you can't complain that he changed once.
@TedShifrin Really? I should be glad I don't put much info out there
20:56
Good night, @Mike.
@Ted Speaking of, John H. Conway has a biography coming out in July..the author came into our class the other day, and he brought a pre-print copy lol
That might be quite interesting, mr eyeglasses.
It's called "Genius At Play"
@TedShifrin But I changes names often and keep the same avatar
We had him here about 15 years ago to give a lecture for undergraduates. I was a bit disappointed, but he's a fascinating mathematician.
20:57
"...John Horton Conway is Archimedes, Mick Jagger, Salvador Dali, and Richard Feynman all rolled into one-a singular mathematician..."
lol
rolls eyes
who wrote that? lol
The author lol
@Hippa: His original name was GTR ... I just remembered.
@TedShifrin waaaat ?
21:01
You're so helpful, mr eyeglasses :D
I forgot her name
@TedShifrin Wow that's unexpected. I was actually wondering where GTR was gone
But she's written biographies of other math people
"math people"
Tu comprends maintenant, @Hippa?
21:01
I think I will wait another hour to go to bed.
When is your biography coming out @TedShifrin
Oh, did she write the Nash biography, mr eyeglasses? Sylvia Nasar?
@TedShifrin yeah now that makes sense... it's awfully awkward :/
Who will write mine?
21:02
Well, @Hippa, I'm glad I could help.
No, not her..this author appeared fairly young
I don't know anyone else who's written math biographies, but I don't keep up. ...
But Professor Conway really seems embarrassed by the contents of the book and says he wants to go into hiding lol
Well, he surely approved/encouraged it, mr eyeglasses.
On the other hand, such projects rarely turn out the way one expected ... And if she's writing sentences like that, I can see it would be embarrassing.
21:05
@ᴇʏᴇs A quick Google search turned up with a Siobhan Roberts
see, @teadawg, google search ... just as I said. :D
Blue and green is said to calm you down.
Red is said to make you anxious.
As with the bull in the ring, @Jasper?
And purple is said to inspire creativity.
Well, I'm out of here for now. Sleep well, @Jasper.
21:06
@TedShifrin C U
21:26
This night I won't sleep too much since at 05:00 it's the game Simona Halep - Serena Williams. They meet again. :-)
(maybe no sleep at all)
21:37
@Chris'ssis You watch tennis?
@JasperLoy Sure. I love tennis. I also played tennis in the past.
@Chris'ssis I tried to play tennis once, but failed miserably.
@JasperLoy There is no such a thing. It was only your appeciation about that I think. Well, one needs some practice for a bit of progress. That's true for all.
21:56
@Chris'ssis I am going to sleep, see you in my dreams.
@JasperLoy OK :-) Sleep well.
Hello!! Is someone of you familiar with PDE's ??
A slightly bit @MaryStar
@Hippalectryon Do you maybe have an idea for the following??
1
Q: Differential equation - Green's Theorem

Mary StarI want to find the solution of the following initial value problem: $$u_{tt}(x, t)-u_{xt}(x, t)=f(x, t), x \in \mathbb{R}, t>0 \\ u(x, 0)=0, x \in \mathbb{R} \\ u_t(x, 0)=0, x \in \mathbb{R}$$ using Green's theorem but I got stuck... $$$$ I found the following example in my notes: $$u_{tt...

All I can is upvote on that one :-)
22:04
Ok... :-)
22:18
Hello @DanielFischer!!! I want to write an algorithm that gets as input two strings s1, s2 and determines if the one is a subsequence of the other.
So if we have for example abcdk and ak, is ak a subsequence of abcdk?
@evinda Depends on the definition of subsequence. Read the definition, and it should be easy to see.
@hippa did you answer already on irc
obviously
@hippa arg you're on ignore
@hippa how to delete you from the list of ignored people ?
@DanielFischer I found this: A subsequence is a sequence that can be derived from another sequence by deleting some elements without changing the order of the remaining elements.

So ak is not a subsequence of abcdk, right?
22:23
@Ramanewbie google
@evinda a bcd k
Oh, I see... So for example ba wouldn't be a subsequence of abcdk, right? @DanielFischer
@evinda Right, that would change the order.
@Hippalectryon How do you gain so many enemies
@ᴇʏᴇs many ?
22:34
One is too many
I hope GTR isn't my ennemy :/ lol
@Hippalectryon Why do people always have you on ignore lol
'always'
I've never been on ignore here afaik
Nice, thank you :) @DanielFischer
23:17
@robjohn I should clarify, I've never gotten a picture of Mars, say, handheld!
@AlecTeal Mars is hard to get with a telescope. It is very small and usually very far away.
@AlecTeal I have a few pictures that I took very early on. They are not very impressive.
23:45
Can the integral $$\int_0^1 w_{xt}^2 dx$$ be written as an exact differential?? Can it be written in the form $$\int_0^1 \left (\frac{d}{dt} ... \right ) dx$$ ??
23:57
@DanielFischer @robjohn @DavidWheeler

Can the integral $$\int_0^1 w_{xt}^2 dx$$ be written as an exact differential?? Can it be written in the form $$\int_0^1 \left (\frac{d}{dt} ... \right ) dx$$ ??

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