@robjohn: Not that I care about 10 rep points, but did you have a moment to check on those downvotes I got suspiciously yesterday?

@TedShifrin I don't care about the rep.

I care about the people that maliciously downvote.

@robjohn Do you have my e-mail? I think I am entitled to knowing who's maliciously downvoting me (and other people).

I wasn't meaning to sound like you did, @Pedro. You missed my war yesterday.

@TedShifrin With Don?

I didn't!

@Pedro Why would you be entitled to that knowledge, especially if the SE team hasn't called it malicious?

I actually voted to delete the answer.

Yeah, @Mike's right.

@MikeMiller I think they told robjohn who's downvoting, and it's clearly malicious, don't be naïve.

Oh, I forgot I can do things like that now ....

@Pedro: I think you and I may occasionally deserve downvotes.

@PedroTamaroff no one told me, and I can't say who I think it is.

@TedShifrin Why?

@Ted Why is the first paragraph of this follow? I assume he means $Diff^+$ (else by Smale's result it certainly is not connected...), and I don't see why connectedness follows from the extension bit. My first thought was the alexander trick but I can't figure out how to apply it.

@Mike: I keep telling you I don't know this stuff!

@Pedro "Don't be naive" =/= the mods have considered it malicious and punished the offenders and thus can tell the users involved

Before the end of the day I'll have won Pedro over to my 'all votes should be signed' proposal! #BuildingTheCoalition #YesWeCan

They shouldn't, though.

I never have downvoted without first putting a comment explaining why.

@Ted That doesn't make sense. You know more than me, and I don't know this, therefore you know this. It's basic logic.

@KevinDriscoll It would certainly be nice if the people who have cast x% of their votes as downvotes would at least justify x% of their downvotes.

Unless it was just total crap.

@KevinDriscoll, if that were the case, that would encourage revenge-downvoting.

You'll love that logic when you start teaching in the fall, @Mike.

Which is what I think I got, @Kaj.

@Kaj it would certainly allow for it while the anonymous scheme doesn't. But it would be revenge downvoting in the open. I think everyone here is smart enough to realize when that's happening.

@TedShifrin, oftentimes I'll downvote questions that are clearly homework and demand us to give them the answer. It's definitely frustrating when I get a downvote or two on answers, and I have no clue why they were justified. Especially when they're accompanied by a handful of upvotes.

@Ted Presumably as a first year I'll be teaching calculus at most... I bet I know enough calculus to get by.

It was your students' logic to which I referred, @Mike.

Yeah, @KajHansen. Opinions on downvotes so widely vary in this community. But I think that they can be very discouraging if unaccompanied by any explanation. This is certainly amplified when users seem to be "targeted".

@Ted Well, I thought you meant students would use that logic on me. But I'm hoping they'll be asking about u-substitution and not diffeomorphism groups.

Well, @Kaj, I flipped out at a 100+K who answered a takehome exam question when the OP specifically asked for no help, just clarification of the question!

hm, caring about downvotes

@PedroTamaroff: I have forwarded what information I have to the community team. They are the only ones who can do anything anyway. I don't know if they will reverse any of the downvotes today, but there is a chance.

@Karl: No, I care about the self-righteous majority who want to turn this place into a homework/exam answer factory.

@TedShifrin I hope that wasn't me. I try not to do that, but sometimes you see the question and just answer from the title. By the time you notice the request in the question, it is too late.

@KarlKronenfeld, it's important to care about downvotes, not from a rep standpoint, but because it tells others trying to benefit from this site that something is wrong with a legitimate answer.

@TedShifrin I was referring to a conversation earlier. I feel too that this should not be a place for doing work for others.

No, @robjohn, if it had been you, I would have bitched loudly in person to you. It was DonAntonio who, I believe, then went on a mini-spree downvoting various of my answers.

there are one or two users here who take things a little too seriously, pouncing on me whenever I make a post. It is shocking if you are new to the site, but after a while I just shrug it off.

@TedShifrin good. I would expect no less :-)

@Karl I care about downvotes that put my answers negative for no apparent reason, since it makes my answers look bad or wrong. I don't care about the rep.

@KajHansen I get the sense that these serial downvotes comprise such a small portion of the pool of votes that it is virtually inconsequential in that sense.

Time for the park. BBL

My point was you can't ignore the powers of supply and demand @Ted

My strong opinions, among others, and frankness seem to have sent Brian into permanent disappearance. I did not appreciate his implicit attacks on me, either.

Brian Scott?

@MikeMiller If you get no upvotes and just one improper downvote, consider improving your answer anyway to make it more attractive to the participants who would upvote it.

Yes, @Com.

I think it is okay to care about downvotes in a more local sense. Sure, the reputation cost is negligible. But in a way, I view upvotes (when voting on answers) to be a kind of "Kudos, nice answer!" which at least makes me feel very good and happy about my answer. Downvotes feel like a signal saying "your answer is either seriously flawed or flat out wrong", which obviously feels bad, especially if you cannot see what is wrong with your answer.

Or, in my case, registering disapproval of the answer's existence, @AWertheim.

But I say so loudly in a comment.

Agreed with @AWertheim.

I rarely downvote a reasonable person for a flawed answer. I comment and try to get it fixed first.

@TedShifrin: certainly, and comments are essential in that way. I generally do not like downvoting, and have only felt compelled to do so if I have left a comment pointing out a serious flaw or error that was flat out ignored by the person who posted it.

Agreed, @TedShifrin.

@TedShifrin, I think your latest downvote is the only time I've seen an accepted answer with negative votes.

High five @AWertheim :)

High five :)

Well, clearly by inspection everyone here leaves helpful comments when they down vote. Now we just extrapolate ot the rest of the Math.SE community and...........

@KarlKronenfeld Usually I end up getting an upvote or something that cancels it out, but that's a good point.

Accepted? @Kaj

You know, when the OP clicks the green check mark to indicate that your answer was the most helpful, etc. math.stackexchange.com/questions/836573/…

Thanks for joining Math Ed SE @Ted

I have had numerous positive experiences teaching and leading an OP to an understanding, but it takes patience, and most high rep people here don't have the patience.

I haven't said much there, @skull, if anything.

I always click up AND accept the amswer

It's the thought that counts Professor @Ted :-)

Oh, @Kaj, I believe that was one of the revenge downvotes to which I was referring.

I only have 793 points :(

I'll look for good stuff you do, @Com.

its ok, but thanks

Its funny how few people frequent this chat compared to the overall activity of the site. I think I have a very different perception of Math.SE because I spend most of my site time in this echo chamber as compared ot the rest of the site.

not that people here always agree, but it seems to happen more than I'd otherwise expect

It's @Pedro's fault — He dragged me here a year ago.

@TedShifrin Wat.

@TedShifrin Diffeomorphisms don't restrict to diffeomorphisms of submanifolds and their images, right?

Back when we used to call him Peter :-)

Um, @Mike. Think dinner.

oh.

Ok @PedroTamaroff, I think I've solved your problem. The only unfortunate thing is that the proof is very non-constructive. I can prove that $n$ is finite for any given $m$, but I have no idea what an upper bound might be. However, I do know that if you need an $n \times n$ matrix for a given $m$, then you need at most a square matrix of dimensions $2n+1$ for the $m+1$ case.

@KajHansen The idea is to use Ramsey numbers, certainly, and define a coloring in an appropriate way.

Interesting. I'll think of an approach that uses them in that case. I managed to avoid them entirely with my method though.

@TedShifrin Well, I've upgraded the bill to lunch and a drink.

is this an interesting property for topological space $X$?: For all $\epsilon >0$ there exists a continuous surjection $f_\epsilon:X\to (0,1)$ such that diam$(f_{\epsilon} ^{-1} ({t}))<\epsilon$ for all $t\in (0,1)$.

$X$ assumed to be metric

Find something interesting about it, @ComTruise

Then it'll be interesting

like the curve $sin(1/x)$ should have this property

topologist sine curve without the left bar

The graph of that from $0$ to $1$, say...?

yes

But that's homeomorphic to $(0,1)$ (or $(0,1]$ if you want) without the left point.

the graph as a subspace of $\mathbb {R} ^2$ is not homeomorphic to the interval though

Yeah it is...

Unless I'm mistaken in a stupid way

no, I'm rather sure the graph of any continuous map $f: X \rightarrow Y$ (with the subspace topology inherited from $X \times Y$ with the product topology) is homeomorphic to $X$

yes

@KarlKronenfeld this is dog

you use the projection for the inverse

@KarlKronenfeld right, I was leaving the possibility open that the proof in my head didn't work

ok so thats not a good example

@TedShifrin You told me you didn't know this stuff.

I don't :)

Yeah okay.

I have taught Guillemin & Pollack something like 8 times ...

@TedShifrin What's $g_i$ supposed to mean? Just some smooth function?

@TedShifrin: Do you think Guillemin & Pollack is well suited for self-study?

Yes.

hmm, if I add the condition that $f_{\epsilon} ^{-1} (A) \subseteq f_{\delta} ^{-1} (A)$ for $0<\epsilon<\delta$ and all $A\subseteq (0,1)$, it might be the case that the functions $f_{\epsilon}$ converge to a homeomorphism

I don't see why that's true. Taylor's theorem I guess. I'll go away now, though.

Yes, it's quite readable, @AWertheim. If you want, I can send you my notes and exercise sets at some point, too.

@TedShifrin: wow, that would be wonderful, thanks!

No, not quite, @Mike. I'm sure you read this in Lee.

Probably, but I've forgotten all the math I learned, @Ted

Email me when you want, @AWertheim. I'll have to scan the notes.

Sounds good @TedShifrin, thanks again. :)

It's often called the $C^\infty$ trick, as I said, @Mike.

Can't find it.

I'll leave you be though.

Hint @Mike: $$\int_0^1 \frac d{dt} f(tx)dt$$

le clasiqué

@ComTruise I can't convince myself that they should converge.

@Pedro Hows your combinatorics going?

@KevinDriscoll Hehe, I don't know.

On bad news, I cannot find my notes.

I prolly forgot them at my uni... =/

And the good news?

goodevening Gentlemen

Hello

Hello.

@KajHansen hello, how are you?

Not being gentle, I take offense to that.

@PedroTamaroff hi Pedro, how is your night?

@KarlKronenfeld hello karl, how are things ?

Not too bad Charlie

@Charlie Not bad. I should be sleeping in a while, tennis tomorrow morning.

And it is fucking cold here.

That's right. It's winter down in the southern hemisphere. It's been really hot this week up here.

@PedroTamaroff I suppose, good luck

@KajHansen good :)

@Charlie Fine, how about you?

@KarlKronenfeld I'm fine, thanks

@Karl You are the gentlest anonymous person I know

Excuse me , but does anyone know what does mean a matrix A with thiis symbol ~ above it?

@MikeMiller lol, tries to figure out if that is a compliment

I'll never tell

@Charlie Out of context, no.

@KarlKronenfeld Clearly it means the matrix $\tilde A$

@MikeMiller and what it represents?

a matrix

thanks

no but really, what Karl said, context is needed

@MikeMiller You never know, it could be some oddball trying out a new notation for determinants.

that's why it was a joke, not to be taken seriously, at risk of death

lol at proof #2

looootta stuff there

wb @robjohn

@TedShifrin Why does any orientable surface embed into $\mathbb R^3$? Is that even true?

Welcome back by the way :D

Huh? $2$-manifold?

Yes, it's true, by classification.

@TedShifrin I didn't say closed.

Compact with boundary?

Even non-compact.

Noncompact? Still think those are classified by genus and number of ends.

Ah, I think I read about that once. That should do it.

I'm assuming that's somewhere in Whitney.

I think we can push any double-points to infinity or something.

And with boundary follows imediately from the general case (consider the double).

Right.

Heya @Ted, guess what?! I'm going back to school in the fall! I just wanted to thank you personally since hanging out in here and reading your messages was the final 'push' that I needed.. It's only KSU and I'm starting out as a third year, but it's a start! Any tips on who to take?

(and by 'push' I honestly have to thank everyone in here for showing me how little I truly know and how much there is left to learn...)

Does this have anything to do with complex analysis?

@MikeMiller why does there exist a "several complex variables" tag?

on that question, or in general?

both

1) because the asker is using the wrong tags

2) why is there a multivariable-calculus tag?

you don't think there should be a multivariable calculus tag?

i do

and by analogy there should be a several complex variables tag

ok

How can I have a question reopened?

I had a legit question closed...

@Bananarama Go to your fridge.

Pick a piece of ham.

Cut it into four congruent circles.

that's gonna be hard considering circles have no volume

Draw the letters, E, G, L, G (yes, the G twice) with mayo.

Then give them to a stray cat and set it on fire.

set the letters on fire, not the cat

If the Gods are merciful, your question shall be reopened in four moons from today.

I would like to set some of my street's cats on fire

the cat must be unharmed

it's tricky

@MikeMiller No, the cat must be set on fire.

the last question you posted that was closed was over 2 months ago

@PedroTamaroff you've been doing it wrong

yes, that's the one

@MikeMiller Oh, damn.

Poor Mr. Kittens.

Is mayo even flammable?

both of your recent closed questions were marked as duplicates

@TedShifrin Wow. it was up for >3.5 hours.

oh, never mind, I deleted it yesterday

oh

it was totally legit btw

then why did you delete it

Heya @Alex: What was?

@TedShifrin the thing that made you furious

I dare not speak the name of he who did it

because it got closed

ah

was it something about a guy giving unsolicited advice on a test question?

so you are a coward who flees from the first sign of adversity

i know your ilk

@DavidKirby: Good for you! We can talk about it if you want ... Later.

my ilk?

@TedShifrin That answer that pissed you off.

@Bananarama Yeah, you had the m but then somone scared it away.

@AlexanderGruber YO.

Oh yeah. It was.

(and is pissing me off now that I'm seeing it)

@PedroTamaroff Yoseph.

I don't know his milk

but it better not be whole milk

that shit's nasty

@AlexanderGruber I think I am being supah clear here

I'm wondering if the student told his professor. Ha ha ....

@MikeMiller you misspelled "delicious"

@MikeMiller what kind of milk is better than whole milk?

literally any other kind

@AlexanderGruber Have you ever watched "It's Always Sunny in PA"?

that's

you don't abbreviate philadelphia to PA

@PedroTamaroff haha oh yes

philadelphia $\neq$ PA = Pennsylvania

Nothing we can do about assholes like Don, either. I first commented within a minute or so of his move.

@TedShifrin who is don?

@TedShifrin I wonder what the community would think about making that suspendable behaviour

I mean the guy asked specifically not to be hinted at

LE MCPOYLES

they would bitch endlessly about it, @AlexanderGruber, and it wouldn't happen

@MikeMiller Damn it, I tried.

PL?

I bet you I'm still in the gross minority, @Alex, sadly.

@Pedro: Philly

piecewise linear?

who is don?

@MikeMiller do you think so? I find it hard to believe that even B.D. and crew would be against that. Their argument basically boils down to "we don't know the asker's motivation, so there's no reason to assume that he's being dishonest / lazy", but in this case the asker directly states that he wishes not to receive hints or solutions

Toric Donut?

A 100k+ twit, whom 've always been nice to before, e en when he messed up. NO MORE.

@AlexanderGruber their argument is not the same as their response

they want an entirely laissez-faire community

That's why people invented bonfires, people.

They are meant to be used.

@MikeMiller you think they're just anarchists?

libertarians

which is just as bad, because libertarians really exist

@Alex: I don't know if you noticed, but immediately after that I got a bunch of downvotes ... I think just about the only ones I've ever had.

@MikeMiller, now now

I think professors need to stop giving takehome exams, too. That bus left the station a long time ago.

@PedroTamaroff edit the answer you linked

@TedShifrin oh wow, that's BS. i'm looking into it.

Thanks, @Alex.

@TedShifrin takehome exams are fine if the questions aren't googleable, or if they're easily googleable and one can just look at the first few results to see if the students copied.

@MikeMiller You downvoted me. LEL

@PedroTamaroff i was trying to annoy you, but you didn't complain about it, and i forgot to undo it.

Everything is SE-able, @Mike, as we've just established.

@TedShifrin search on SE for them...

Besides, if @TedShifrin gave a take-home exam, it would be guaranteed to be hard as hell.

@Mike: Did you finish the proof I outlined?

no, my consistent failure depressed me so I took a nap instead

How do I prove the student didn't come up with it himself, @Mike?

* spanks @Mike *

@Kaj: Years ago I gave take-homes in classes like 4010 and 4220.

There's no doubt the 4010 exam was worse than Graham's 4 and a half hour final.

shudders

LOL ... Not nearly so bad as you're imagining.

If you look at my finals objectively, they're not unfair at all ...

Just every one else has wussed out ... :( More rationale to retire.

Does this question have anything to do with conformal geometry?

I can't make it out it's asking, so I'm not willing to admonish the OP.

I agree. The 4250 exam could've been a LOT worse. And I did pretty well on the 4010 test...it was just a long.

Because who knows, maybe it's actually about conformal geometry.

it was just long**

People confuse conformal mapping (appropriate) with conformal geometry (diff geo). Is there a conformal mapping tag? @Mike

What does that question have to do with conformal mapping?

It drives me crazy how all your courses have numbers.

@TedShifrin one of the advantages of the diamond is my students are afraid to post my questions on here.

A lot of PDEs are solved by conformally mapping the domain to a standard one ... I didn't read the problem.

I couldn't read the problem.

@PedroTamaroff i know right? they assigned me "MAC1140" when I first got to UF and it took me several days to figure out what the hell that was.

it appears to be pre-calculus and algebra.

@Pedro: At MIT even the departments have numbers. Math is 18.

@AlexanderGruber My courses have names, like "Analysis I", "Advanced Calculus", "Complex Analysis".

It isn't even that hard!

@Mike, whatever "precalculus" actually is...

@KajHansen it's usually "what is a function? what is an inverse of a function? what's a polynomial and what are its roots? what are some tools for factoring and finding rational roots?" sometimes it even includes "what's a limit?"

florida is bothersome because of two different math prefixes. When I was Assoc Head it drove me nuts.

@PedroTamaroff at my old uni we had course numbers with course names, but we referred to them by the names and just used the numbers for registration. Here we still have both but everybody calls them by their numbers.

usually, in my experience, students leave knowing none of the above

We have names, too, @Pedro, geez.

mine's Mike

It's always just struck me as a nebulous term.

It's background you need for calculus, @Kaj.

@TedShifrin Like knowing how to add and subtract.

no, @PedroTamaroff, precalculus assumed that

as it turns out assuming students know how to add and subtract is dangerous indeed

At this pace we'll have pre-precalculus in no time.

@TedShifrin oh there's even more actually. we have MTG for topology MAC for precalc/calculus/etc MAA for analysis MAD for algebra MAP for applied math and probably others

Reminds me of...

alex is MAD and he wants everyone to know it

"Pre warm up, post work out."

@MikeMiller you're goddamn right.

@PedroTamaroff i'm likin' them groovy pushups.

Oh, @Alex, I saw only core level!

IN-DEED-

@alex: You feeling better?

@TedShifrin a little. They put me on drugs.

Agh.

I guess they're going to give me some kind of injection in the back of my head that will fix it for a while.

I hardly took codeine after my major surgeries ...

@AlexanderGruber Why?

Damn, @Alex. I hope this will get better.

@TedShifrin it's tramadol, which is not quite so potent. (non-addictive, I guess)

@PedroTamaroff I have a bunch of herniated discs from my whiplash injury last Halloween

@AlexanderGruber And are you looking forward to surgery?

My father had one, and it hurt like hell.

you know what hurts? gall stones

@TedShifrin yeah that'd be good. I'm a pretty physical person so it'd be pretty not good if it didn't get better. i'm into weightlifting and play rugby, neither of which are real compatible with neck injuries.

@PedroTamaroff sooner it's over the better, i say

long as the surgeon doesn't mess up

Are they planning surgery, then, @Alex?

Ah sorry to hear that Alex

@PedroTamaroff What you wrote does not obviously show that $\sin$ is surjective.

Agreed.

Eschew splitting into real and imaginary parts!

Thanks again, @Alex. I look forward to a resolution :D

@TedShifrin I'm not sure. I think they're waiting to see what happens.

For your health, I'll cross fingers, toes, and other things.

thanks.

and thanks to you too @Kevin

is this nonsense? (i.e., unsalvageably so)

@Mike: Stop stalling and do your exercise.

@Mike I'm stalling as well.

I'm supposed to be writing my Research Statement. Instead I'm talking with the gf on the phone.

@KevinDriscoll I'd rather talk with gf on the phone.

Here comes a gf

I'm outta here. G'night alll.

$\sum x_n x^n$

@TedShifrin I'm still recovering from the deepseated depression you induced.

I hate your jokes more than I hate exponential generating functions.

Wait for the faculty in grad school, @Mike. I'm a teddy bear.

Goodnight, @TedShifrin!

Night, @AWertheim

@Pedro Generating function!? facepalm

@TedShifrin Ah, but the problem is that I don't know anything, not your insults.

Insults? You're as bad as the viral memes.

@Kaj: You shall be dead.

@TedShifrin Well, the normal person's solution would be to start knowing things. But I've decided to become an economist instead. They can be bad at math.

@TedShifrin took me a minute to figure out what "wb" stood for. I checked my profile page from my phone, but I was not back to my computer, so I didn't see the message until later. :-)

@PedroTamaroff why do you say no one likes exgfs? They are just as useful as normal generating functions.

What are exgfs @robjohn? Naturally, Google returns explicit results.

@KajHansen exponential generating functions

Ah, got it.

@Robjohn we use exgfs for quantum field theory, though we just call htem generating functions

well technically theyre generating FUNCTIONALS

can someone help me check this? the bounds don't seem to match up math.stackexchange.com/a/839251/33907

they seem too lose to be good

@lyme The messages on this topic are so spread in the transcript of this room over several pages, so I created a new room, so that a conversation about this is feasible.

Is room info and transcript displayed normally for you?

Now even the chatroom is displayed strangely.

It is displayed like this for me: i.sstatic.net/LFkSi.png

For me looking like that is a sign of a poor internet connection

Now it looks normal again.

Thanks for the reply, Mike; I asked basically to know whether I am the only one experiencing this.

I've had that happen before, since my internet provider does a rather poor job of providing internet.

Hi @KevinDriscoll what's new in the world of Physics pal.