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3:00 AM
@CookieToast i would like to see the CookieToast 5000 line proof...
 
The other way to have written the initial proof is to have done the contrapositive: Suppose $s\mathbf{x}+t\mathbf{y}=0$ for $s,t$ not both zero. If $t\neq 0$, then $\mathbf{y}=(-s/t)\mathbf{x}$ and $-s/t\in \mathbb{R}$ so the vectors are parallel. The analogous argument holds for $s\neq 0$ and so the vectors must be parallel.
 
semiclassical goes for the classic proof.
 
lol
I'd have written 'without loss of generality' in order to say $t\neq 0$ but eh
 
so no ones gunna touch my diameter closed ball question?
 
either way
 
3:08 AM
@Faust something like this
 
lol
 
right haha
 
markers don't actually appreciate that
 
haha sadly no
 
i have actually seen people who have no idea how to do a question just write every kind of relevant piece of information they could think of in hopes that whilst marking it i will recognize the correct solution.
 
3:12 AM
My old physics prof would give you 9/10 points on a question for writing everything down, and only 1 point for solving/getting the correct answer. It was wierd
 
@Faust I am certainly not going to touch your closed balls, diameter or no!
4
 
Loool
 
@XanderHenderson its not like they are open balls...
 
Sir, I am a gentleman.
 
@CookieToast Ha! That particular Google Image result was actually from this answer: math.stackexchange.com/a/798261/23353
 
3:14 AM
Bookmarking for future use against professors :P
 
haha nice
 
@CookieToast I actually agree with the spirit of that, tbh. When grading quiz problems (at least at the intro level) I care more about the setup than the final result.
However, the set-up is more than just "what numbers are given in the problem"
That won't get you very far in my book. But, for instance, properly writing out the kinematic equations in a projectile motion problem is more important to me than if you solve them correctly in a quiz setting. The latter is math, not physics.
 
I typically assume that if a student managed to set up the problem correctly, they probably managed to get the right answer, too
 
Eh, people run out of time
 
i was always really good at physics problems if you just need an answer
 
3:20 AM
There's a whole bunch of reasons why someone might make progress on a quiz problem without reaching the end
 
yeah, but because I've assumed that they arrived at the correct answer, I've already given them the points :P
 
just dont ask me how i got it.
 
grading sucks :\
 
yuuup
 
i dont mind it that much
 
3:21 AM
So glad I don't have to grade lab reports this semester ugh
 
im not doing any this semester cause im not allowed to cause of funding but i dont mind it
 
@Semiclassical yeah I have no issue with her. And she intentionally structured her exams so we didn't have enough time. I liked that because it really taught me how to work under pressure
 
It was pretty cool actually. She gave 7 or 8 problems of increasing difficult, but only expected the class to get through the first 4 or 5. But if you were lucky enough to see the trick to one of the more difficult ones, you could set it up for a few extra points.
 
3:23 AM
Morning @AkivaWeinberger
 
@xander haha the class before us had a "song of the day" written on the board. That should have been one of them!
 
looks outside
G'evening
 
Its probally morning somewhere
6:26 a.m.
Monday, January 22, 2018 (GMT+3)
Time in Moscow, Russia
 
@TedShifrin pseudophpt.github.io/riemann now you can play with it
 
@Xander grading can be quite funny sometimes
It kinda alternates between being amusing and pure frustrating + monotone. Probably more of a negative experience than positive though
 
3:35 AM
Hi all, could someone helps me to understand a homework question?
"Give example of function classes that are preserved under uniform convergence."
What's the meaning of "function classes that are preserved under uniform convergence"?
 
There are certain properties of functions that are preserved under uniform limits
 
@User0.618 For example, is the pointwise limit of a sequence of continuous functions continuous?
what if you change "pointwise" to "uniform"?
 
I suppose they mean certain "niceness" properties, like continuity or differentiability
 
@User0.618 perhaps you can start by giving us an example of a function that is uniformly convergent
 
@AkivaWeinberger That would be my assumption, as well
 
3:40 AM
@orbit-stabilizer i used no css frameworks, just p5.js
and thanks
 
To be honest it sounds like lazy question writing to me
 
@Faust You probably aren't going to find a function that is uniformly convergent, but you might find a function that is the uniform limit of a sequence of functions...
 
Thank you all! I understand the question now. I'll try to solve it by myself
 
yo
 
yeah i guess i should say an example of something that is uniformly convergent to a function?
 
3:41 AM
oy
 
oi
 
yo @Daminark just want to make sure I have the wording of how I am understanding this question correctly
yo-yoyo
 
:D
 
3:42 AM
must... resist... urge... to make "Yo mama" joke...
 
(a)
 
nope... can't do it. Yo mama so fat, she ain't $L^p$ for any $p$
2
 
lol wut?
whats $L^p$
 
So we have this family of maps $i_C : Mor(C,A) \rightarrow Mor(C,A^{\prime})$ where each of the family comes equipped with $f_C$ and $g_C$ that make the diagram commutes
right ?
p-integrable functions
under some ~
difference being measure 0
 
A function $f$ is in $L^p((X,\mu))$ if $\int_{X} |f(x)|^p \,\mathrm{d}\mu(x) < \infty$
 
3:44 AM
It is a class @XanderHenderson
 
where "function" doesn't really mean "function"
 
yeah
 
oh ok
 
but an equivalence class of functions that are "equal" in the sense that $f \sim g$ if $\|f-g\|_p = 0$
 
yeah
precisely
 
3:45 AM
where $\|f\|_p$ is the $p$-th root of the integral above
 
your saying his moma's so fat shes infinite dimensional?
 
:D
 
I'm saying she's so fat that she can't be integrated :P
 
@Daminark
 
lol ok
 
3:45 AM
she got HEAVY tails
 
O.o
 
lol
@XanderHenderson Yo momma is so fat that she isn't a small category :P
 
@XanderHenderson your star board seems to be very insightful contributions to the site today.
 
@Faust Yay!
 
@XanderHenderson YAY
 
And here I was, about to compare Yo mama to the monster group. :(
 
btw what is Fractal geometry
it seems interesting
 
fractal geometry is geometry done with fractals
 
I am surrounded by crazy people.
 
You stare at the Koch snowflake and do drugs
 
3:48 AM
man, I wish
 
hahaha
 
And contemplate how the B in Benoit B. Mandelbrot stands for Benoit B. Mandelbrot
 
I spent most of my day today making sure that I could prove that singleton sets in $\mathbb{Q}_p$ are fractal in the sense that advisor defines the term
 
@AkivaWeinberger we already do drugs when we study things like schemes and stalks etc
lol
 
no
it stands for $_{\textrm{Benoit B. Mandelbrot}}$
 
3:49 AM
> The New York Times obituary stated that "he added the middle initial himself, though it does not stand for a middle name".[1] But other sources suggest that he intended his middle initial B. to recursively mean Benoit B. Mandelbrot, thereby including a fractal (his mathematical discovery) in his own name.[2][3]
Whoa, it's real
I thought it was a cheap joke
 
seems very interesting @XanderHenderson
 
funny that the NY Times would give him credit for the discovery of fractals
 
you do geometry with things like analysis intead of algebra
 
he might have been the coiner of the term, but the kinds of objects he described were well known before he came along
 
@XanderHenderson No, the NYT quote ends at the first sentence
 
3:51 AM
@Adeek Yup. I want a metric, and a measure!
 
yeah with algebraic geometry all you need is a scheme
 
@AkivaWeinberger Hrm... still, the quote is wrong :\
I'll sheafify you!
 
it sounds that we are about to rob a bank
I will go scheme on the bank now
lol
 
I've heard lots of people credit him for fractals
 
I sat in on an algebraic geometry class last year
I gave up about half-way through
 
3:52 AM
I don't think it is possible to learn this stuff from a class
I think you need to be a hermit at home
and learn it by yourself after hours of reading multiple books
 
I probably would have enjoyed it if I had more time to actually think about it, but it started getting deep into the weeds of sheaves and stalks and germs way too fast for me
and I had / have my own research to deal with
 
lols
 
> In 1982, Mandelbrot expanded and updated his ideas in The Fractal Geometry of Nature.[20] This influential work brought fractals into the mainstream of professional and popular mathematics, as well as silencing critics, who had dismissed fractals as "program artifacts".
 
as I said, he definitely coined the term
 
Heh, cool, apparently people at one point thought the Mandelbrot set wasn't really a fractal
and that it was the computer's fault
 
3:54 AM
indeed
 
I think very philosophically @XanderHenderson
a sheaf is essentially a human
 
though they didn't think that it wasn't fractal, only that the odd behaviour was an error
 
what humans do is as follows you see objects in real life and then after that you extract local data
same thing with sheaves
so sheaves are humans
 
@Adeek what about the converse?
 
humans are sheaves as well
 
3:55 AM
no proof?
 
no
 
Conjecture i say!
 
lolz
 
@Adeek yeah I think that should be the idea?
 
oh okay
So basically we have this
 
3:56 AM
Or
Actually hold on I'm not too sure now
 
$(i_C,\phi_C,\psi_C) :Mor(C,A) \rightarrow Mor(C,A^{\prime})$ which commutes with the maps $Mor(C,A) \rightarrow Mor(B,A)$ ?
I have an idea to solve it but I am not sure if I am interpreting this correct
correctly *
 
I need to sleep; g'night
 
show that if $S $ is compact, there $x,y\in S $ so $|x-y| = d(S) $ any hints 4 me?
 
nights
 
@XanderHenderson enjoy your sleep dinner.
 
3:58 AM
Good night!
 
@Daminark you know stuff about polar bears right? help me!
 
I'm not too familiar with polar bears
 
@Faust try working through it. It is not hard
it is better to think of something by yourself :)
 
@Adeek so it's a bit odd for me to interpret this thing
 
@Daminark why ?
 
4:00 AM
im just not sure its so obvious that i dont really know where to start
 
Like, "commute with the maps Mor(C,A) -> Mor(B,A)"
 
yeah
 
Oh wait wait
 
that is what I am confused about
 
like its closed and bdd the diamtere must come from two points in the set
 
4:01 AM
I think I get it now
$C$ is over any object in the category
 
yeah
 
So you have a family of morphisms $i_C:Mor(C,A) \to Mor(C,A')$
 
yes
I agree
together with also more morphisms $f,g$ right ?
 
Such that if $f:C\to C'$ is some morphism, well it'll induce $\widetilde{f}:Mor(C,A) \to Mor(C',A)$
 
ohh
 
4:02 AM
Okay wait let me upload a picture of this diagram
 
yeah I understand
 
But in a nutshell you'll want those to commute with these $i_C$
It'll be a commuting square basically
 
yeah
where the first morphism going down $mor(C,A) \rightarrow mor(C,A)$ is the identity ?
 
Uh, not quite, one sec
 
where do you upload those diagrams ?
 
4:12 AM
I'll upload here
 
how do you it ?
 
I think it only works on computer but you use the little "upload" button next to "send"
 
latex thingy?
u draw on it
 
Anyway never take me on faith in stuff like this since I'm utterly clueless but I /think/ this is how it works
 
it craps out latex?
 
4:13 AM
yeah
 
I agree with you @Daminark
 
or how make empty set?
 
Mathematicians might want to put more focus on topology constructs, cause these system's lack of dependence on details like geometry might give more insight on how amorphous matter behaves
Imagine an amorphous solid which has an inherent ordering and topology, some kind of collective behaviour might be interesting will take place there
 
taco\
 
4:20 AM
thanks @Daminark I will take it from here :P
I am gonna go to work to solve this problem and read Vakil
cya l8er :) nights if I don't come back toda
 
night
 
nights @Faust
 
@Adeek catch you around! And good night!
 
4:42 AM
Reposting this because it's quite good
I should buy this book at some point
 
@akiva how's that possible?
@AkivaWeinberger
Gif 1?
 
The second and third gifs explain the first one
 
@AkivaWeinberger its cheating?
 
The only other explanation is "magic"
 

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