« first day (2485 days earlier)      last day (2539 days later) » 

5:00 PM
@Dodsy wait I have a bridge? Wao reacts only
 
By the way, @Daminark @EricSilva I'm curious if my solution to the prime-power polynomial puzzle is the same as yours
 
Trolls live under bridges.
 
'cause I solved it earlier today
 
dude trolls live under a bridge u should know this @Daminark
 
How'd you do it?
 
5:00 PM
oh sweet
 
There needs to be a language without nouns and only adjectives
 
Weird @EricSilva and @Dodsy
 
swiftly swaying swaggy lots.
 
$\Bbb R[x]/\langle a_0+a_1x+\dotsb+a_nx^n\rangle$ is an $n$-dimensional vector field over $\Bbb R$
Well, specifically, it's a finite-dimensional vector field.
 
this is probably the same as mine
 
5:02 PM
$\{x^p+\langle f\rangle:p\text{ prime}\}$, however, is an infinite set.
 
This is beyond clever though
 
So any collection of $n+1$ of those is linearly dependent.
 
although I spent epsilon time thinking about this.
 
@BalarkaSen It took me days to think of this
 
@Daminark go away. We don't want you here, you troll!
 
5:03 PM
I was working with the other graders on this with a hint from Laci and it took us 3 hours
Or something
 
But, yeah, the that linear dependence, without the ${}+\langle f\rangle$ at the end, is the desired polynomial.
 
3 hours is a long time.
 
@Duck sad reacts only
 
trolls are better than backstabbing orcs
 
Shorter than it took me.
 
5:03 PM
>.>
<.<
 
That hint from Laci was, in fact, "linear independence"
 
@BalarkaSen like Dodsy?
 
D:
 
> dodsy threw demonark under the bus
 
5:04 PM
Dodsy dies
 
Most of the time I was thinking about it, I was thinking about it the wrong way
This morning I changed my perspective to the right one, and it just kinda hit me
 
But yeah @Akiva this is of a similar form to my solution, basically equivalent
Wait no this is definitely equivalent
 
this exactly my proof
 
@Dodsy that gif is ridiculous and should be burned.
 
Has bieber ever come to indiana, Duck.
 
5:06 PM
I managed to convince myself that flagging that would be going too far
 
Oh good!
 
Kek
 
I feel nauseous
 
Let's just message this out of the screen
 
make it go away
go
away
 
5:06 PM
I deleted it.
 
@Dodsy Idk. How would I know?
 
You would know, you're from indiana.
 
no I'm not
I always lie about where I'm from.
 
Rekd
...such as right now?
 
lmfao.
 
5:08 PM
nice staxxxer skills
 
@Akiva such image
 
Thank you.
Bow. Bow. Wave.
 
@Daminark -_- I mean that if someone asks where I am I'll tell them somewhere else so they cannot come to my house and murder me for bad math.
 
@Duck why would you not crave this fate?
 
"You forgot to label your axes, you monster"
"For that I shall kill you with my axes"
 
5:09 PM
snaps ayy
 
@Daminark because the only one who gets that privilege is myself.
 
this is a really unproductive room today...
 
I wonder where Meowmix has been.
 
i'ma peace out
 
that's not a joke
for all I know, you people are all serial rapists
 
5:10 PM
"Say minus one-twelfth one more time, I dare you, I double-dare you m*therfucker"
12
 
lol
 
You said you were from Indiana unprovoked
and I have the proof
nobody asked you
 
so?
I probably said that cause it suited the conversation
and why do you care where I'm from?
 
meh drop this convo
 
It's dropped.
Like a sack of stones.
 
5:12 PM
dropped
 
One of the problems on that puzzle sheet was, "Show that every real polynomial of odd degree has a real root."
Seriously?
 
Well you need an ego booster sometimes
 
@AkivaWeinberger that's true by definition...
 
Haha, I guess
@TheGreatDuck confused noises
 
It was probably set up for another puzzle which would use it
 
5:14 PM
@AkivaWeinberger a real polynomial outputs real numbers?
 
Yes
Well, for real inputs
 
so all roots are real
 
But yeah if I remember right, the way I had said my solution was that the set of polynomials with prime power order at most $n$ was a vector space of dimension $r$, but that the ideal generated by a given polynomial $f$ capped at degree $n$ was another vector space of dimension $k$
 
Yeah I'm going to log out from here too and do something unproductive
this is less than unproductive
 
@TheGreatDuck It's false for even degrees; $x^2+1$, for example
 
5:15 PM
"Call me imaginary one more time." "You're imag-"
 
The next one is, "Show that $1+x+\dotsb+x^{p-1}$ is irreducible for $p$ prime," which I feel like I should know how to do.
 
@AkivaWeinberger that's not a real polynomial
 
@TheGreatDuck A real polynomial is one with real coefficients. That's equivalent to having real outputs for real inputs
 
Now, if you increase $n$ to $n+1$, you will necessarily increase $k$ to $k+1$ as well
So that $n - r - k$ never increases
But then there are infinitely many prime numbers so $r$ has to increase, eventually $n-r-k$ will become negative
 
@AkivaWeinberger oh -_-. I thought it meant one with a range of all real numbers.
 
5:17 PM
Oh
No
 
So then the ideal generated by $f$ must intersect the space of prime power polynomials eventually
 
@TheGreatDuck In any case, odd-degree polynomials are minus infinity at the left and plus infinity at the right, so they have to hit zero at some point
IVT.
 
ok fair enough
 
@TedShifrin no isometries?
 
yeah, that's what he means
 
5:24 PM
I didn't mean to act like I cared to know where you live Duck. I just think that you were the one pretending to be Balarka. I don't want you to think I'm some sort of weirdo or anything. I honestly just think I am a detective.
 
@Danu hello. How's it going?
@Dodsy someone was pretending to be balarka? 0.0
 
Yeah and he's from Valparaiso Indiana.
 
weird
 
15 mins ago, by Mike Miller
this is a really unproductive room today...
 
Yeah so, sorry if I made you feel uncomfortable.
 
5:25 PM
reminisces fondly about the "good old days"
 
However, I will drop my personal investigation.
 
fair enough. I'm definitely not from that area.
how do you know where they lived? Did a mod tell you or something?
 
It's not worth discussing. I'd rather leave it now, and move on.
 
@Dodsy fair enough. Is there any way we could talk in a private room by ourselves on here? There's something I want to tell you that might be relevant.
 
No, I'd honestly like to leave it and wash my hands with it. I think I've already embarassed myself enough today.
 
5:29 PM
no i mean if you mean what I think you mean, you need to hear this.
 
No thank you.
hey sha
How are you today?
 
@Dodsy fair enough, but if @BalarkaSen loses control of their account again, please let me know immediately.
 
hi Dodsy, I'm good, how are you?
Also, guys, say we want to factor $u^2+v^2$. We could do this in two ways:
$$
(u+v)(u-v)\quad\text{or}\quad(iu+v)(-iu+v).
$$
When would one prefer the second factorisation? I'm guessing when $u$ and $v$ are complex, but I'm not sure.
 
@TheGreatDuck This was on a separate chatroom, Duck.
 
oooh
I thought someone was stealing accounts again
 
5:32 PM
@Sha. You're being sloppy.
Factorization is unique in $\Bbb C$ up to multiplication by $\pm 1, \pm i$.
 
A wild Ted appears.
 
uuuh
 
hi Nate
 
(u+v)(u-v) = u^2 - v^2
NOT u^2 + v^2
 
Hallo, mein Freund
 
5:33 PM
@Danu: Yes, the generic Riemannian manifold has no isometries. Obviously, you're working with homogeneous spaces, but you have to be very careful about how homogeneous they actually are.
Guten Tag, Nate.
 
@Ted oh huh, that doesn't tell me much. Is that equivalent to saying that $\mathbb C$ is algebraically closed?
 
No, factorization of polynomials (in any number of variables) over a field is always essentially unique.
 
@TedShifrin stupid question but would 1/z = a - bi where z = a + bi?
 
Duck already told you your error.
No, Duck, not unless $|z|=1$.
 
wat
we never had this conversation before
 
5:34 PM
oh sorry, I missed that
oh right
that was stupid
 
Duck, there was no comma.
 
@TedShifrin I never really thought about that.
 
why would I put in a comma? This is an informal chat.
 
@Danu Oh hey, didn't notice you there.
 
I was just asking because I wanted to write a little bit of motivation for the study of Riemannian submersions
 
5:35 PM
Duck, never mind. I was telling Sha that you had told her her error. Read what I wrote.
 
I framed it as dual to Riemannian immersions (following the original paper by O'Neill)
 
oooh
:p
 
I don't think of it that way at all, @Danu, I confess.
 
@TedShifrin How do you think of Riemannian submersions?
 
@ShaVuklia Nothing is stupid, Sha.
 
5:36 PM
that makes more sense now
 
Hey @Ted, @Sha, @Danu
 
hey @Dami
 
Fiber bundles, @Danu. Not always true, but you probably know Ehreshmann's theorem — any proper surjective submersion is one.
Hi, Demonark. I pinged you earlier.
 
@TedShifrin: For codim 1 things, I suspect you should be able to get away with transitivity on T^1 M
 
I've given up on Queens Ted. The manager just sent the email back to the guy I've already been dealing with, who will probably be angry that I tried to go over his head now. Thus, I am relying solely on UWO.
 
5:38 PM
I haven't thought about it, @MikeM, but likely true. I know that symmetric spaces are much better than general homogeneous spaces for purposes of invariant cohomology (on a general homogeneous space, invariant forms aren't even necessarily closed). I haven't pondered this aspect.
 
@TedShifrin If the total space is complete then you get a fiber bundle
 
Well, Nate, you still were not treated fairly, so I think what you did was reasonable.
 
Oh, of course transitivity on T^1 M is the notion of symmetric spaces.
 
Thank you, Ted.
 
@TedShifrin So, I realized something quite intriguing in response to that surface geometry thing we were discussing the other day. Were you aware that partially folding a plane preserves the rules regarding opposite and adjacent angles between intersecting lines?
 
5:39 PM
I must be going, I have to do some homework and study some math. I'll see you guys around.
 
@Danu, doesn't that follow from properness?
Bye, Nate.
Duck, it's still the plane.
@MikeM: Is that obvious?
 
yeah, it just never occurred to me that the same rules of geometry applied. :p
 
@Danu Proper surjective submersions are fiber bundles. Compactness of the domain is easier than properness.
 
@TedShifrin It's just the theorem that symmetric spaces are homogeneous.
(complete but blah blah blah)
 
Oh, so you're saying the unit tangent bundle of a symmetric space is .... ?
 
5:41 PM
@TedShifrin decided to try moving objects along the polygonal 3D model instead of a smooth curve. Locally everything is Euclidean so it's mostly trivial.
 
a homogeneous space itself
 
@TedShifrin Not assuming properness
 
@TedShifrin anything neat you've been working on lately?
 
Why is that, @MikeM? I should know that, I guess.
 
I'm sorry, I've got my words wrong.
 
5:43 PM
Hi
 
Hi, DogAteMy.
 
What's the name for a manifold that looks the same in every direction? (At every point there's an isometry taking one tangent vector to any other at the same point?)
 
Symmetric spaces are homogeneous because you have the symmetry at the middle of a geodesic connecting any two points
 
I thought this was symmetric spaces but that only guarantees an inversion symmetry
 
The geodesic is there because they are also complete
 
5:44 PM
I need to show that the polynomial $(x^p-1)/(x-1)$ is irreducible
 
We're talking about unit tangent bundle of symmetric space.
Ah, DogAteMy. That's a standard trick.
 
How does one go about proving C(XxY, Z) $\isom$ C(X, C(Y, Z)) in the locally compact category? (w/ compact open top)
I forget this
 
@Ted Heating up?
For the jumble
 
Yup, Demonark.
 
@Akiva Gauss did it you can too :D
 
5:45 PM
@TedShifrin Is this @me?
 
Yes, @Danu.
 
@EricSilva No, that's the opposite of true
 
It's definitely not opposite, DogAteMy.
 
@BalarkaSen whatever man
 
Perhaps not 100% correct, though.
 
5:46 PM
@TedShifrin Then I don't get why :P Was my comment irrelevant?
 
look at davis and kirk or something
 
lol
yeah maybe i'd do that
 
@BAlarka: It surprises me, actually, since it seems to imply that separate continuity implies continuity.
 
@EricSilva a priori that's rather ambitious.
 
@Danu I was claiming that, furthermore, the isometry group acts transitively on each unit tangent sphere
 
5:46 PM
@MikeMiller For a symmetric space?
 
@Daminark it was in jest
 
I thought you were claiming something about the entire unit tangent bundle, @MikeM.
 
Yeah. That's not true, I don't think.
 
It's not true, no
 
@TedShifrin Yes, but that follows from Danu's statement.
 
5:47 PM
That'd be too strong
 
SU(3)/SO(3) shouldn't work
 
I actually don't know a "recipe" for the unit tangent bundle. I know how to give the tangent bundle as an associated bundle.
 
but does have the inversion symmetries
Hm? Have $O(n)$ act on a sphere
 
Plus it'd make the notions of n-symmetric spaces obsolete haha
which are not obsolete :D
(I hope)
 
what's an n-symmetric space?
is that the notion I was trying to say?
 
5:48 PM
@Danu: BTW, if you want a reference for the stuff I pinged you with earlier, Spivak discusses it in detail in Volume 4.
 
not $\sigma_x^2=\operatorname{id}$ but $\sigma_x^{n}=\operatorname{id}$
 
Lel Eric
 

 
(where $\sigma_x$ is the $n$-symmetry at $x$)
 
Ah, my ChatJax finally failed.
@Balarka, did it fail for you too?
 
5:49 PM
derp, just n, not n+1
I need 3-symmetric spaces in my thesis
 
What is an n-symmetry?
 
Hmm, it did?
Nope
Oh you mean the previous version. I updated it
 
@Ted good for me
 
Ah, I haven't had to update yet.
 
@MikeMiller So a symmetric space has a 2-symmetry at any point. An n-symmetric space an n-symmetry
 
5:50 PM
I dread having to do it on my iPad and phone.
 

 
What is an n-symmetry?!
 
the number of times you apply it before getting the identity
 
ok im done
 
I'll have to resurrect those tricky instructions.
 
5:50 PM
somehow one of my messages had a weird symbol when i edited
 
You're right, sorry
 
if you post it, you post... "nothing"
 
I'm epsilon right but what I said there wasn't literally true
 
But I have to think if it matters
 
I'm still confused though so tell me )
:)
 
5:51 PM
You guys have lost me and I'm distracted by ChatJax issues, so ... I'm ignoring this.
 
@TedShifrin what's wrong with it?
 
@EricSilva Are you busy later today?
 
Robjohn announced some change in MathJax server that requires updating bookmarks.
 
@MikeMiller An n-symmetry around $x$ has $x$ as isolated fixed point and its derivative to the power n is the identity.
 
5:53 PM
aha!
 
So let me see if symmetric spaces have just 2-symmetires or if it's indeed more
 
@mike unsure
 
No, you're fine.
 
I have some galois theory homework to do
but it might not take long
 
Zee
@TedShifrin
 
5:55 PM
In the flesh
 
I just realized that Salamon Appendix D is a 5-page proof that (if int f, int h are positive, and $h$ is weakly positive in that you can integrate a nonnegative test function against it and always get a nonnegative answer) you can solve the equation $\Delta u + e^u h = f$, which should be enough to get Kazdan-Warner's results for surfaces
 
Weird, it still works on my iPad.
 
This is weird
 
It's just Duck's stuff that's broken @Ted
 
Zee
Why is one variable complex analysis a core gradute course? Pretty useless
 
5:56 PM
@Danu I haven't been posting any mathjax
 
No, no, the MathJax change stopped ChatJax from working for me, finally. But it's still ok on my iPad and iPhone. I don't understand.
 
Oh...
It's fine for me
@MikeMiller So do you get that the derivative is $-1$ for free?
 
@Zee: It shouldn't be useless. It's beautiful material and it's way beyond the usual undergraduate course (at least, as I taught it).
I taught a lot of sophisticated stuff in there.
 
Complex analysis is da bomb
 
@Danu Yeah it seems that way.
 
5:57 PM
@MikeMiller So why is that?
 
Zee
@TedShifrin it is pretty but it's not used anywhere today , all the important stuff is in several variables and complex manifolds
 
I was confused because this implies that symmetric spaces carry orientation-reversing symmetries when they're odd dimensional
 
Does it have to map a geodesic to its reverse?
 
That's an idiotic remark, @Zee.
 
Zee
Enlighten me
 
5:58 PM
$$G(x)=\lim_{m\to \infty}\frac{1}{m^{N_x}}+\frac{1}{m}\sum_{n=1}^{N_x-1}\frac{a_{nx}}{m^n}=x$$?
 
I'm fed up with comments like that.
 
@Danu An involution is diagonalizable in O(n), and [1, 1, ..., -1, -1] only has an isolated fixed point if all terms are -1
 
@Mike is this where the results you're talking about are? projecteuclid.org/download/pdf_1/euclid.bams/1183533899
 
@Zee Think about Riemann surfaces!
 
apparently
 
5:58 PM
There is plenty of work on Riemann surfaces, still
 
they have like 5-6 papers or something
 
First-year graduate courses are not cutting edge research. They're necessary knowledge that's background for the general mathematical community.
 
ah ok
 
this is the baby one
 
@Danu I haven't been posting mathjax. there's a special symbol "" that can be posted and literally renders to nothing in the browser. I can post blank messages and it's kind of funny to see what it does. I've been posting a few tests every now and then to see how it interacts with mathjax.
 
5:59 PM
alt-0173 or something ?
 
Salamon solves that eq'n for all compact n-manifolds, which surely works into the general proof of their theorems, but the change of conformal class formula for scalar curvature involves a |df| in higher dimensions
not just a laplacian and exponential
 

« first day (2485 days earlier)      last day (2539 days later) »