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8:00 PM
@MattN Hmm. I don't know your notation. Expectation?
 
@JM the trick is not to try to digest...
 
@JM Breathe?
 
@JonasTeuwen Yes.
 
@MattN And $H$?
Some subspace of $L^2$?
 
8:00 PM
Ah, sorry, I was just about to explain.
 
Okay.
 
$Z$ is a finite Abelian group and $H$ is a subgroup.
I have an almost proof but I messed up my sums somewhere because I can't get the right constant in front of the thing.
$H^\bot$ is the orthogonal complement of $H$.
 
Oh well, constants are futile.
Except when you're chasing them :-(.
 
@tb Yeah. Though if I can't digest in two hours or so, I move on for the time being... often things are clear hours after.
 
Meaning: all the characters that are one for all $h$ in $H$.
 
8:01 PM
I don't know what the orthogonal component is in a non-Hilbert(Banach) space.
 
Here's the sums:
 
@JonasTeuwen "annihilator"
 
Aha.
 
$$ \begin{align}
\textbf{E}_{\chi \in H^\bot} \widehat{f} (\chi) &= \frac{1}{|H^\bot|} \sum_{\chi \in H^\bot} \widehat{f}(\chi) \\
&= \frac{1}{|H^\bot|} \frac{1}{\textbf{P}_Z (H)} \sum_{\chi \in H^\bot} \widehat{f}(\chi) 1_{H^\bot} (\chi) \textbf{P}_Z(H) \\
&= \frac{1}{|H^\bot|} \frac{1}{\textbf{P}_Z (H)} \sum_{\chi \in H^\bot} \widehat{f}(\chi) \cdot \widehat{1_H} (\chi) \\
&= \frac{1}{|H^\bot|} \frac{|Z|}{|H|} \sum_{\chi \in H^\bot} \widehat{f \cdot 1_H}(\chi) \\
&= \textbf{E}_{\chi \in H^\bot} \widehat{g} (\chi) \\
 
Please do some \newcommand :-).
PING! Food!
 
8:03 PM
@JonasTeuwen What does it mean?
 
Some thing was undefined.
 
In the meantime, I have to leave. See you guys later!
 
see you!
 
@JM Bye!
 
Well, so you have ... $\leq$ already! 8-)!
 
8:04 PM
@JonasTeuwen The ds fonts, I've taken it out.
@JM See you later!
 
@MattN What does your one to third last line sum over?
@JM Bai bai! Have some good fire water. Cheers!
 
Oh, that's the same as the line above it, sorry.
$\chi(z) \psi(z)$
 
I dislike asking bad questions very much...
 
And I dislike symbol manipulation if I mess it up.
 
I really dislike it if I have nothing else to drink than water.
 
8:08 PM
And I dislike people who talk too much.
 
Do you like yourself?
 
@JonasTeuwen Me?
 
Me? I'm rather indifferent.
 
@JonasTeuwen he explicitly wrote that he dislikes that kind of people
 
@Ilya Hi, what an unexpected sight!
 
8:09 PM
@MattN No, skullpatrol. You should like yourself as you're the bro.
@Ilya 8-)).
 
@JonasTeuwen : D
 
good evening, everybody
 
Hi Ilya.
 
Hi Ilya
 
8:11 PM
Ah, maybe I do have to show $\leq$ and $\geq$!
Haha, I'm done!
 
@tb oh, even you're here :) I thought your gravatar was blind
 
@JonasTeuwen Thank you!
 
8-).
 
You saved my day : )
 
Cool!
 
8:13 PM
No, it's the wrong way around : (
 
Is this Additive Combinatorics notation?
 
No, it's not.
 
(looks ghastly)
 
Yay! : )
 
Sucks monkeys!
 
8:14 PM
Thank you, it's my own notation.
 
Yes, it seems to be. I think you've just messed up somewhere as I would do the same.
 
: )
 
And I'm still exhausted by what I've seen at the Red Light District in Amsterdam.
 
In the book the identify the characters with $\xi \in Z$.
 
What has been seen...
 
8:15 PM
...can't be unseen.
 
What has been mutiplied by zero can not be unmultiplied by zero :D
 
@JonasTeuwen No, I have not messed up. I just didn't realise that I have to show $\leq$ and $\geq$.
 
@MattN Oh, that's usual :-).
 
@tb what do you not like? That I write $\chi \in \widehat{Z}$ instead of $\xi \in Z$?
 
@MattN that the notation will break down horribly as soon as you'll deal with infinite groups.
 
8:20 PM
@tb But the entire chapter is only about finite groups. And is that a yes?
 
No.
 
Actually I'm not done. : (
How does $\leq$ and $\geq$ even make sense in $\mathbb C$?
</3
 
Am I the only one who finds the first comment here quite offensive? Could you please flag it if you agree.
 
@JonasTeuwen Do you have any other ideas regarding the proof?
 
@BillDubuque Done.
 
8:34 PM
@BillDubuque There is nothing wrong with it. I upvoted it.
 
@BillDubuque It's not possible to edit comments when it's more than two minutes since they were posted.
 
@BillDubuque I do find it impolite but not flag-worthy. I'm siding with Brian's latest comment.
@Gigili 5 minutes, but that's a detail :)
 
@tb Ah yes, two minutes was for chat messages!
 
@BillDubuque I don't think that it warrants flagging $-$ quite $-$ but I do agree that it's pretty impolite. Some of that may just be a side effect of Patrick's English, which is good but a little limited.
 
And I find it hilarious that someone with a history of offensive comments and suspensions for such wants people to flag a mildly offensive comment. lol!
2
 
8:37 PM
That's in Amsterdam indeed.
 
4
Q: How many times can you halve a number?

CharIs there an formula stating the number of times you would have to halve a number to reduce it to some value less than or equal to $1$? For example, for $6$ it takes three halvings: $6/2=3$, $\ 3/2=1.5$, $\ 1.5/2=0.75$. Also, is there a representation using the floor function in conjunction? ...

 
Hey @Gilles.
 
^^^^ this question is off-topic on Computer Science. Should we migrate it to Mathematics?
 
@Gilles looks like it would be perfectly on-topic here. Might be a dupe, though
 
@Gilles I agree with Theo.
 
8:39 PM
(but that shouldn't impact the migration)
 
@tb I know it's on-topic. What I'm asking is, is it worth migrating?
 
Poor me.
 
if you already have 50 similar questions, there's no point
 
@Gilles I would support migration. I can't think of a duplicate off the top of my head.
and in case it is a dupe, someone would point them out to the OP which will be helpful in any case
 
@MattN Why?
 
8:41 PM
@Gigili I'm stuck with the proof I posted above.
 
@MattN Umm, I wish I could help you. Why don't you post a question on the main site?
 
@tb ok, it's yours now
 
@Gigili The last time I posted a question about additive combinatorics on main I got zero answers and had to figure it out on my own.
 
@BillDubuque I'm more puzzled by the fact that this comment has now garnered 4 more upvotes since you brought it up here...
 
@MattN Don't believe the hype.
 
8:46 PM
@MattN Should I force someone to help you? (I have a sawed-off shotgun)
 
@tb As pointed out above, one of them is mine.
@BillDubuque About additive combinatorics?
 
I upvoted it, too.
 
@Gigili Hm.... : ) Sounds good. I suppose we could force them to do a lot of other stuff as well. Should we take the teddy?
 
Is this really a math question?
1
Q: Logic circuits with constraints of how long can signal "wait" in wire

SteffenDefine wait time of signal A as number of gates, that any signal in circuit passes during A remains unchanged (i.e. A is in wire, not passing any gate). It should be possible to define wait time: we organize LC from left to right, from inputs to output(s). Then it is possible to divide the LC to...

looks like CS to me
 
(I hope it's not loaded though, we don't want any injuries, right?)
 
8:50 PM
@MattN Whoever you think might help you more, just write down the name and pass it on to me. (of course, it's the new methodology since they don't help you voluntary)
 
@Gigili : )
 
I find it really sad what MSE has come to. There is now a "pack" mentality attacking new users for sins they don't even know about. I come here to try to teach math, not to watch users bully new users over issues that have absolutely nothing to do with mathematics.
9
 
He was trying to welcome the new user, just like what we always do by posting a comment and explaining how it works.
 
@BillDubuque I must say I prefer the Latex community by far.
 
8:54 PM
@Gilles looks a bit borderline to me, honestly. I wouldn't vote to close it as off-topic but if you think it would get better answers on CS or maybe DSP then I'd say go ahead and migrate.
(but there are a few users here who are a bit touchy when it comes to such decisions, so maybe it would be best to wait a few hours)
 
@BillDubuque "Pack" mentality, in my opinion, is a natural consequence of the Darwinian evolution of any web site as creative and innovative as this one :D
 
@MattN As I said, I'm puzzled. You used to complain very loudly about much more light-spirited comments by DP, for example.
 
Seems like Skullpatroll have read too much Nietzsche, or too little.
 
Or maybe too much of the Origin of the Species :D
 
@tb I explained it here but maybe that's not direct enough.
 
9:01 PM
@MattN yes, I saw that, but that's a wrong reason to embrace that comment.
 
@tb I know.
 
One thing that completely puzzles me. Are some folks really so offended by imperative questions that they find it justifiable to post such rude unwelcoming comments to new users?
 
@Gigili He did it rudely though.
 
@N3buchadnezzar BTW what is the biggest difference between this community and the Latex one?
 
@BillDubuque Apparently there are. I can't relate to either that or posting comments to posts not showing any work.
 
9:04 PM
@ymar Unintentionally.
 
But what I can relate to even less is unnecessary rudeness.
 
@Gigili That I do not know.
 
@skullpatrol the friendliness and the warm community
 
@BillDubuque Apparently so, though I really don't understand why.
 
@N3buchadnezzar They probably haven't read much Nietzsche either ;)
 
9:07 PM
@BrianMScott I think it's the pack following Arturo's pet-peeve.
 
@ymar I'm pretty sure since he admitted so in his other comment. We don't need to welcome new users by being unkind to active/old users.
 
This is simply bizarre.
 
It's getting crowed in here!!!
 
And hilarious.
 
aka pack mentality?
 
9:09 PM
LOLBBQ.
 
@tb But at least Arturo's boilerplate is polite about it.
 
This is precisely the reason why I tried to propose some sort of standardization of these meta comments. Without such we can get random comments like this one whose author believes it polite but which may offend others. Only by having the community vote on such meta comments can we avoid these issues,
 
@BillDubuque As almost always, I do agree with the abstract concern. However, I don't think the specific instance warrants the kerfuffle.
 
Well then. Seeing as no one is interested in doing Fourier analysis with me I'll go to bed and cry myself to sleep.
 
26 people in the room and no Konig???
 
9:14 PM
Good night!
 
Later.
 
Good night, Matt
 
Sleep well, @MattN.
 
Hope I didn't overdose on bizarre-ness right now, that might give me surreal nightmares.
 
The latex part have something like this
51
Q: Text building blocks

CaramdirThere are some replies that are used quite often. For example, the first reply to many questions is a demand for a minimal example. These replies should typically include a link with additional information. So I thought that it might be useful to collect some standard replies for quick copy&p...

 
9:15 PM
@N3buchadnezzar wtf?
 
@N3buchadnezzar Yes, I think someone already linked to that in my proposal on meta
 
@N3buchadnezzar That's what Bill brought up here
 
I am just saying that it is a good idea =)
 
@N3buchadnezzar What is "the friendliness and the warm community" like in their chat room?
 
Im with @N3buchadnezzar on this idea. Im usually editing and re-editing my comments a million times so as not to offend the users.
 
9:31 PM
When people say "dupe" on this chat, what do they mean?
 
@ymar duplicate
 
@tb Oh, I see. Thanks, that explains a lot.
 
Does anyone have any tips on writing $\Omega$ by hand? Mine always look terrible...
 
I start at the bottom left. :)
 
Horse shoe perhaps?
 
9:35 PM
Does anyone know any good alternatives to MSE?
 
@Bill: No, I don't.
 
@BillDubuque In what aspect?
 
@BillDubuque Losing faith? :-)
 
@robjohn read the transcript...
 
Any general level math site with folks seriously interested in math and not poetry etc
 
9:36 PM
@tb I should have done that.
 
@BillDubuque I know a few norwegian sites, but not anything as active as this one.
 
I'd welcome less activity and more contents, though.
 
PF is much worse than this site...
@BillDubuque www.artofproblemsolving.com is decent.
 
@BillDubuque Well, reddit.com/r/math is full of jerks, so there's one for you to avoid...
 
@N3buchadnezzar I haven't visited aops in some time. But it was more high-school level than upper level iirc
 
9:40 PM
@BillDubuque I guess it deppends on which parts you are visiting. The Calculus forums were good for a while. Few moderators, and mostly filled with fun questions.
I would not say mostly high-school, I would also include first two years at university. But I clearly see your point.
 
The thing I like about MSE is that it averages undergrad level, which I think poses the best opportunities for teaching.
 
And learning to :D
 
I always liked the wide diversity we have here and I know of no site having such a broad spectrum. There's something to learn for everyone. However, the tendency seems to be towards the more and more basic stuff.
 
@tb are you sure that's not just a result of an increasing maturity in you?
 
There are some internet fora but the ones I know are much less active and prone to technical difficulties.
 
9:45 PM
@AntonioVargas I'm old enough to converge towards the more silly side :)
 
A horizontal asymptote
 
@tb That's the natural evolution of a general level math site as it gets exposed more to the masses. At some point we may need to split into two sites, undergrad and above, vs. high-school and below, or somesuch
 
You could always try and start an Advanced Math Stack Exchange :)
 
I would join...
 
@tb I haven't noticed this tendency. Is it strong in your opinion?
 
9:47 PM
@skullpatrol MO
 
MO needs more hard analysis.
 
@N3buchadnezzar Oops ... I forgot sorry :(
 
@AntonioVargas Too much rings and fields over thar... for my taste.
 
MathOverflow, M.SE, and MathUnderflow. Hm hm.
2
 
Underflow? is that like an undercurrent :D
 
10:00 PM
@AntonioVargas How would you define "Hard Analysis"?
 
There should be a badge on that site called "flow rider", not sure what for though.
2
 
@ZhenLin Or MathForHobbits?
@N3buchadnezzar Maybe for drunk people that give good answers?
 
@JonasTeuwen This article was posted in a comment here earlier today, I think. It must have gotten me thinking about it.
 
@JonasTeuwen Would not that include most of the persons answering and asking questions there?
 
Oh no. I think that was such bullshit.
Even though it is written by Tao.
Why the hell would you care about the distinction?
 
@AntonioVargas You mean cool analysis with cool estimates. So, you mean harmonic analysis right?
 
@JonasTeuwen Because I like hard analysis, that's all. That's why I want more on MO.
 
@AntonioVargas More analysis is always better!
@AntonioVargas Has it been your birthday recently? I seem to remember your profile saying "23"...
 
@JonasTeuwen I have some friends in harmonic* analysis. I honestly haven't had the time to pick it up myself.
@JonasTeuwen Yesterday :)
 
@AntonioVargas Congratulations!
@AntonioVargas Harmonic analysis! It is very hard. Not soft.
 
10:04 PM
Yeah, typo.
@JonasTeuwen And thanks :)
 
:-). You're working on harmonic analysis.
 
Am I?
 
Sorry. I mean.
What are you working on?
 
As of right now I'm working specifically on zeros of polynomials via asymptotic analysis.
 
Sounds very cool.
I'd like to know more about that.
Do you have something written down?
 
10:09 PM
Actually yes, I wrote up a little summary of some of the stuff I've been interested in for a presentation to some physics students. I'll email it to you.
 
"Jonas had them green Bottom jeans, jeans
functions with fourier, with the fourier
The whole site was lookin’ at her
She hit the flo’, she hit the flo’
Next thing you know
Jonas got tao tao tao tao, tao tao tao tao"
 
Would be great :-).
@N3buchadnezzar I'll have what you had.
 
@JonasTeuwen enjoy
 
@JonasTeuwen Sent.
 
10:24 PM
Who's active now?
 
10:39 PM
Yes, who is active now?
 
I am.
 
Can you help me with a Galois Theory question?
 
Unfortunately, not. I don't know what a field is, as I already mentioned earlier today.
 
Yeah I didn't think so. You're an analyst right?
 
I'm the softest of soft analysts, yes. So soft in fact, that I wouldn't call myself an analyst :)
 
10:43 PM
No, you are Professor X :D
 
But seriously, you're going to ask about cyclotomic extensions, about which I really don't know the first thing.
 
What about just automorphism groups. My question isn't really that dependent on cyclotomic fields
 
You can try, but I'm not too confident that I can answer.
 
Well suppose I have two cyclic groups of automorphisms. One we'll call $K=\{\sigma_{1},\sigma_{2},\sigma_{3},\sigma_{4}\}$ and the other let's call $H$. If the subgroups of $H$ are generated by $\{\sigma_{2}^{2},\sigma_{2}^{3},\sigma_{2}^{4},\sigma_{2}^{6}\}$, what happens when I form the quotient group $H/K$ ?
 
@tb A topalyst?
 
10:48 PM
@BrianMScott I guess so, but a measured one :)
But my presence here really misrepresents my interests: yes, I like topology a lot, and yes, I love functional analysis, but I like to think of myself as a metric geometer, but maybe that's just an attitude that will wear off with time...
@DavidK I warned you and I feel ashamed to say: I have not the slightest clue.
 
Professor X is my super hero. :D
 
That's ok. Me neither really.
 
Should I add a homework tag to a question that isn't homework anymore, but used to be and I'm doing it now to prepare myself for an exam?
 
I want to learn physics, analysis, topology and algebra, and differential equations and and and..
 
@ymar I think that's up to you. By adding that tag you'd indicate that you'd prefer hints and indications, not full solutions, but people don't pay that much attention anyway, I believe.
 
10:56 PM
@tb Thanks. I don't mind full solutions, so I'll leave it as it is.
 
@ymar No. If you want just hints, say so very explicitly $-$ and even then you may get some full answers.
 
I think encouraging the use of the homework tag is good, so many people ask help for homework that are part of their grade
it's not good to give full, detailed solutions for those
 
@tb Is there such a thing as non-metric geometry?
 
@skullpatrol I guess not, but it's more like geometry based on metric spaces as opposed to differential geometry or Euclidean geometry.
 
Thanks
 
11:04 PM
It's a relatively new field that was very much influenced by the work of Gromov.
(of course, it has roots going back to Dehn, or Alexandrov and Busemann)
 
Is it possible to explain i few words what differential and hypergeometric geometry is?
I tried reading about it on wikipedia, alas it did not make much sense to me at the moment.
 
I never heard the term "hypergeometric geometry". Differential geometry is the geometry of spaces determined by smooth functions on Euclidean space I'd say. Like spheres, tori, and so on.
 
hypergeometric geometry?
 
I found this Is it any good? @tb
 
sorry, bad connection
 
11:09 PM
Ops sorry, I meant Hyperbolic geometry! bushes
 
@skullpatrol I remember the thread, it was okay. The interview by Berger with Gromov in the Notices might be worthwhile to read: part 1, part 2
 
Thanks again :D
 
@N3buchadnezzar Hyperbolic geometry is the geometry of negatively curved spaces.
"Triangles look thinner than in Euclidean space"
 
As opposed to Elliptic geometry.
 
Where triangles look fatter, yes.
Okay, that's it for me today. See y'all later!
 
11:20 PM
Later.
 
11:40 PM
@BillDubuque Hey!
@robjohn How's it going?
@Gigili Hello there!
 
@PeterTamaroff Pretty good. How are you?
 
Good. Back from a study-a-thon for physics.
Did you get the schedule mail for mod chat?
 
Hey @Peter.
 
Sorry guys, I'll b right back I'm not in my house and I've been called to the table. It'd be rude not to go! 10 mins TOPS!
 
I'm off to bed, good night.
(I've been called to bed, it'd be rude not to go)
 
11:48 PM
howdy folks
If I have a bunch of datapoints in 3space, how do I efficiently decide if they lie on a line and determine the line's slope?
I have equations for 2space, but not for 3space
Also, I need to see if they're going in one of the 6 cardinal directions (up, down, in, out, left, right
 
@JoeStavitsky Have you tried a least squares regression?
 
Robjohn, if you mean sum squared error, I have the equation for 2space but not for 3 space.
 
if $f\in L^1$ and $g\in L^p$, young's inequality gives us that $\| f*g\|_p \le \|f\|_1 \|g\|_p$. in a proof folland makes the claim that $\|f*g\|_\infty\le \|f\|_p\|g\|_q$. i don't see why, can someone help me transcend my density?
 
@robjohn, also I think that gives slope, but not linearity, ie doesnt it assume linearity?
 
@JoeStavitsky It tries to find a line that best fits the points and then you can see how well those points fit that line.
 
11:56 PM
of course by holder we have that $\|fg\|_1\le \|f\|_p \|g\|_q$ where $p$ and $q$ are conjugate
and in this proof $p$ and $q$ are conjugate
 
@robjohn, ok, but like I said how to do for 3space?
 
@Gigili Back here!
 
i retract my question
 

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