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2:00 AM
@TedShifrin Yeah, absolutely, that is good advice.
The thing that impresses me most about this student is her resilience, she was in my precalc class, came in knowing really nothing (came from a bad school system), fought discouragement the whole way and ended up getting an A in the class. Medal of honor stuff, I really was impressed.
 
The trouble comes, @AlexG, with students who ask for a letter after not having made any effort to distinguish themselves or get to know one. I had a business major in my probability class who was very smart, ended up with an A-, asked me to write for about 15 places for Ph.D. in different sorts of business. I wrote, but I couldn't say much. I told him he should have been coming to office hours and working on the more challenging problems to impress me :)
That's a good letter, @AlexG, particularly if you can now say she's gone on to do well in subsequent courses.
 
@arkamis I feel your pain though. It takes me a bit of time to remember how to use the parallelogram law at times (which might not matter yet to you, but will when you get to hilbert spaces/inner product spaces)
 
Yeah, she's kept coming back to my office hours, and to my neighbor's office hours too (who's teaching her current class)
 
In a situation like this, @AlexG, I like to ask the student to ask other teachers to send me a sentence or two which I can perhaps quote in my letter.
 
Ooh, that's a good idea.
 
2:04 AM
For example, since students only have a limited number of letters for REUs or grad school, etc., I often incorporate comments from a few other people because there just aren't that many letters allowed :)
heya @Committing
 
@TedShifrin Yeah, I suspect that may have been me for one of my grad school letters :p a lot of my office hours people ended up being physicists, and I didn't want all my letters to be from non-mathematicians. In retrospect, I think I shouldn't have cared.
 
Hey @ᴇʏᴇs @Ted @MikeM
 
@TedShifrin that seems like system gaming. banned!
 
Hi @Committingtoachallenge
 
(if MSE were reality)
 
2:05 AM
The other thing you might do, @AlexG, is show your letter to your faculty mentor (or a faculty member you feel comfortable with) and ask for suggestions/feedback on how to write such letters.
@AlexG: Not gaming. Trying to have maximum impact in as few words/letters as possible.
No one ever suggested this to me. I've just been doing it for the last 15-20 years. :)
 
@TedShifrin Yeah, I was just kidding.
 
Is it normal to be bad at one field and good in another(in math)?
 
no, every mathematician is a renaissance mathematician
 
Not ideal, but not unusual, @Committing. For example, @AlexG is great at algebra and hates analysis.
 
@Committingtoachallenge I thought everyone was Gauss except me
 
2:07 AM
@Committingtoachallenge only if the bad field is analysis.
 
I have much better intuition for analysis/geometry/topology than I do for the formal symbol-pushing of algebra :)
 
I am bad at real analyis, but I 'get' metric spaces
 
Nevertheless, I've written an algebra book that has pictures in it :P
 
@Committingtoachallenge do you just not like completeness?
 
2:08 AM
oh, it looks like monster @Pedro just entered.
Where are you in your travels now, @Pedro?
 
I wish I learned general topology first before learning about metric spaces..I feel like knowing metric spaces already is messing me up in my abstract learning of general topology
 
No, mr eyeglasses, better to have concrete examples before ridiculous abstraction. Most topology courses use metric spaces as examples to go on and build on.
 
I am bad with the terminology they use in real analysis with the weirestrass continuity and limits there, but I get limit points when they are phrased using neighbourhoods
 
I have no idea what you're talking about, @Committing.
 
@Committingtoachallenge hey I think I get what you mean
 
2:10 AM
I always use neighborhoods :)
 
@Committingtoachallenge My professor defines everything sequentially..sequential continuity, sequential compactness, sequential limit point, etc. ($\epsilon - \delta$ continuity is a theorem for us lol)
 
I am saying I can't remember the $\forall \epsilon \gt 0, \exists \delta \gt 0, |x-a|\lt \delta \implies \implies |f(x)-f(a)| \lt \epsilon$ or something
 
Sequences can be more natural for a lot of people, mr eyeglasses. We have a sequences/series class (intermediate level) that does exactly that.
 
@TedShifrin I don't like it
 
Like for example do prefer the $f(B_\delta(x))\subseteq B_\epsilon(f(x))$ definition of continuity?
 
2:10 AM
@TedShifrin Back home. =)
 
@AlexanderGruber Yep
@AlexanderGruber That is much better, I can see it and draw it nicely
 
Welcome home, @Pedro. I'm guessing you had a great time for the most part, except for being sick.
 
@Committingtoachallenge yeah totally with you there. Makes a lot more sense to work with sets than elements to me.
 
@TedShifrin Is there a reason that a harmonic analyst would prefer sequential stuff? (My professor did his PhD at Princeton under Elias Stein)
 
Any Australians here?
 
2:11 AM
It's totally identical, @Committing. You need to get over this mental block.
 
@TedShifrin I have been trying...
 
Yes, one uses sequences and convergent subsequences all over analysis. I do compactness that way in my multivariable course, because it's more elementary and concrete than other approaches for that level.
Some people choose to do things for sound pedagogical reasons, mr eyeglasses, and I see no reason to think this person didn't do so.
 
(my internet is dropping at uni, how sad.........)
 
You could also just belligerently deny the existence of infinite sets, denounce the real numbers as a sham, and never become good at analysis. That's worked pretty well for me.
 
I am in QLD @Parth
 
2:13 AM
smacks @AlexG
 
@TedShifrin Yeah. It was pretty nice.
 
@AlexanderGruber I don't like the 'hyper reals' if it counts for anything
 
@Committingtoachallenge I'm in India. You know what I'm about to bring up, right?
 
@Committingtoachallenge is that that $\mathbb{R}$ plus $\pm\infty$ thing?
 
Well, next trip to the US, @Pedro, there won't be me to visit in Georgia. Thank goodness :)
 
2:13 AM
@AlexanderGruber HAHAHA.
 
@AlexanderGruber Nah it's worse
 
infinitesimals, @AlexG
it's actually quite cool, based on the compactness theorem in model theory.
 
hi @Committingtoachallenge.
Lots of chatter tonight
 
That's 'cuz I'm babbling too much, @Mike, but I'm leaving soon.
 
2:14 AM
Hi @MikeMiller
 
@ParthKohli I don't follow the news much atm if that is what you are asking
 
@Pedro: Did you ever meet other Alex?
 
hi @ᴇʏᴇs
 
Okay i have to leave, I can only post every bloody 20 attempts at timeouts...
 
@TedShifrin No, I couldn't find him. =/
Next time it is.
 
2:15 AM
Ok, bye @Ted
 
@MikeMiller was a good acquaintance already. ;)
 
@AlexanderGruber It's infinite numbers and infitesimals
 
Growl, @Pedro ... Well, you definitely need to keep Berkeley on the list.
 
abel prize for John Nash and Louis Ninrenberg
 
So my posts are out of order
 
2:16 AM
@Pedro: But @Mike gets tiresome after a lunchtime or so. :D
Better to forget about us and go do some work, @Committing :)
 
@TedShifrin Yep
 
That's not a good joke
 
inb4 infinitessimals don't exist
 
No, @AlexG, those of us who've had cancer don't appreciate that "humor."
 
Sorry @Ted. :/
 
2:20 AM
@AlexanderGruber How's your back, by the way?
 
@PedroTamaroff It's alright.
 
@AlexanderGruber what happened to your back?
 
@TheEmperorofIceCream Infinitesimals.
Infinistesimals happened.
 
Car crashes aren't very infinitesimal, IMHO.
 
Mods shouldn't try to make jokes.
 
2:22 AM
Mods are people too.
2
 
Stop mod cruelty. Mods are people too.
 
@TheEmperorofIceCream It got rear ended by somebody last year, had to get slowly massaged back into place.
 
The first doctor I'll need to find when I move is a good chiropractor. Sigh.
 
@TheEmperorofIceCream Haha, you're not gonna like me much, then. ;)
 
OK, I'll leave so @Mike can take over the chattering.
 
2:23 AM
oh that's terrible. I had terrible back pain in high school. I could only get about three hours of sleep a day because of the pain.
 
No thanks, @Ted.
 
Oh, I thought you wanted to be in charge, @Mike.
 
Not around here.
 
@TheEmperorofIceCream it was upper back/my neck mostly, so it didn't really bother me, except when I was using the computer, reading, or writing.
In other words, all the time.
 
@Mike: LOL ... Where, then? .... I've forgotten the bordism stuff. Is $\Bbb RP^3$ an element of order two?
I've had lower back and neck/shoulder, @AlexG ... and it all sucks. I was almost immobilized for several months with lower back agony about 10 years ago. The chiropractor totally saved me.
 
2:26 AM
I just watched the 2015 math panel breakthough prize in mathematics. It think it was terrible, really awkward and it got kind of dark at moments, I also didn't understand anything Kontsevich said, and the moderator wasn't versed in the art of speaking either.
 
@Mike: I guess $\Bbb CP^2$ is the best low-dimensional example? Anything with nonzero signature can't bound?
 
What was the panel about? People who got prizes?
 
@TedShifrin So how did you get started playing bridge?
 
@TedShifrin the lower back stuff seems like it would be the worst, to me. Neck stuff is terrible, lots of headaches, but at least you're mobile.
 
Started in college, @Stan, partly because I'd watched my parents play. That's a few generations removed these days, I think.
But lots of MIT undergrads played serious bridge, and it was a fun "distraction" from politics and work.
 
2:30 AM
@TedShifrin: Yes, correct. You know a bound for every orientable surface and every orientable 3-manifold bounds by characteristic classes...
And as you mentioned signature is a bordism invariant.
 
I used to know this stuff centuries ago.
What in the world is $\Bbb RP^3$ a boundary of? :)
Guess we need some surgery ...
 
@DiscipleofBarney Yeah, they got a lot of major figures, Kontsevitch, Tao, Donaldson, Lurie, Taylor and Milner and started to ask them philosophical questions.
You can find it here: youtube.com/watch?v=eNgUQlpc1m0
I also think they way they were seated and the camerawork was terrible
 
Oh yea @TedShifrin Someone in my class mentioned that they watched your multivariable calculus videos and that you explain much better than his professor lol
 
I want to watch that video of Ted
 
@TheEmperorofIceCream Hmm, I will give it a shot in a bit although sounds sort of boring or nothing of any meaning will actually get said.
 
2:36 AM
LOL, mr eyeglasses, I'm probably not the worst explainer on earth :P
 
@TedShifrin that sounds fun. We used to play Tichu a lot in my REU
i have been trying to revive it hear but people aren't sociable at UF
 
@TedShifrin you're one of my favorite (former :P) professors
 
Hmm, I thought grad students were always sociable in a nerdly way.
 
I like people who can explain things
 
@TedShifrin not here, really. it's a very disconnected department.
 
2:38 AM
@StanShunpike Do you hate me then :(
 
My dad is good at it too. I guess that's why he's a professor
 
Huh? @Stan
 
Didn't you say u were retiring?
 
I guess that's one reason people go to visitation days, @AlexG, to scope out such things.
oh, that's what you meant ... not like you'd ever taken a class from me, @Stan ...
@Stan: As you'll find out, there are plenty of professors who are not good teachers.
Neither necessary nor sufficient :D
@AlexG: I've never heard of Tichu.
oh, ugh, I'm seeing really fabulous condos/apartments show up on Zillow, and they'll all be gone when I get there in 2 months. :(
 
What is Zillow?
 
2:40 AM
a real estate app :)
website, in fact
 
@TedShifrin I hope you will be happy wherever you choose to relocate to
 
in my day, you had to pound the streets ... now you find housing and dates on-line :P ... oh yeah, and homework answers.
thank you, mr eyeglasses ... I'll do my best.
I wonder how your classmate stumbled across the lectures, mr eyeglasses .. seems to be happening a fair amount.
 
I think this is the first time I've heard your name from a classmate
 
odd conversation ... :D
 
@TedShifrin so your father was a composer? Did he get his music played anywhere?
 
2:47 AM
Sure, @Stan ... even the Boston Symphony ... lots of chamber music (Juilliard and Fine Arts quartets, among others).
There are about 4 CDs out with his music on 'em (some whole, some part).
 
That's awesome! Wow so cool
 
You can google Seymour Shifrin and find 'em.
OK, g'night, all.
 
Nice, I was about to ask. Nite ted!
 
Night @TedShifrin
 
3:05 AM
Hello Math SErs
 
Hello
 
3:30 AM
It's been twenty years since I've been using the letter, and still everytime I see a $\rho$ I call it a "p" in my head
 
3:45 AM
hello @Clarinetist
 
4:06 AM
Here is the answer to the second part of your joke :-) @ThomasAndrews
 
@ᴇʏᴇs Bart, I feel terrible now. =(
@infinitesimalsimplicio You are not sleeping yet?
 
@Mike This looks maddeningly hard. A klein bottle doesn't work either : you can use a disk instead of S^1 in your bundle. That gives you a compact 3-manifold with boundary the bottle.
 
Correct.
You'll only need results that are in the first three chapters of Hatcher.
 
@JasperLoy what's wrong?
 
4:18 AM
@TheEmperorofIceCream Just my OCD themes worsening. Sometimes, I do certain things and then things get worse. I did not expect those things I did would worsen things of course, and now I blame myself for doing them, which makes me feel even worse.
 
what things?
 
No point going into the details, you won't get it. =) But what I said will suffice.
 
does your doctor know the details?
 
No, I will work with a therapist when I am ready.
 
We all make mistakes my friend.
 
4:22 AM
so no one in the world knows the details?
 
Yes, except myself. Sometimes, it's no use others knowing the details. Sometimes, them knowing the surface helps already.
 
ok, although I'm not sure that's the way to go
but im not an expert
 
I am going to take a nap, see you. Keep me in your prayers.
 
I will, i'm going to bed. Enjoy the nap
 
4:57 AM
@infinitesimalsimplicio what up bruh? So are u a math guy or a physics guy?
 
I'm just a guy :-)
 
5:54 AM
@infinitesimalsimplicio lol you must be a cousin of QMechanic. He's a mystery too :P
Although he's a crazy intense mod lol. He's almost at 16,000 edits O.o
Guess SE wouldn't survive without dudes like him
 
That's true, there are a lot of hard working mods out there.
 
6:12 AM
@infinitesimalsimplicio yeah, I didn't realize it but I saw some of the music mods talking and there seems to be a lot of mod teaching that goes on when new mods are inducted. one of the guys in the Music SE said its like a cross between being a janitor and a referee :D
 
They make this web site/network a much better place.
 
6:36 AM
What in the heck is $\mathfrak{gl}_n$?
All $n\times n$ matrices with the commutor as the lie bracket? What does that mean, 'the commutor as the the lie bracket'
$[a,b]=ab-ba$?
What is zero iff they commute
 
6:58 AM
yes
 
Has anyone hear read Derek Goldrei's Classic Set Theory before?
here*
 
@Committingtoachallenge The commutator of $a,b$ is defined to be $ab-ba$, so it is just saying the bracket operations you equip to the space of matrices is taking commutators. They are zero if they commute.
Lie brackets can be defined abstractly, so they want the operation to be explicitly defined.
 
7:13 AM
^_^
 
Huy
7:30 AM
Morning, @MikeMiller.
 
7:43 AM
Will a basis of an R^n vector space always have n vectors?
 
That depends on your definition of a "basis," right?
 
A set of vectors which are linearly independent and span V I guess? I wasn't aware that there are multiple definitions.
 
hello
 
hello my friend
 
i need some help in functional analysis
 
7:51 AM
Are you considering $\mathbb{R}^n$ a vector space over $\mathbb{R}$? if that is the case then yes, otherwise not necessarily, for example as a vector space over $\mathbb{Q}$ a basis (if you accept the axiom of choice a basis does exist) will have cardinality of the continuum. @Howcan
 
I'm just trying to say @Howcan that your question can be answered "by definition" :-)
 
OH
Thank you, and right now we're just dealing with $\mathbb{R}^n$. But I'll keep what you said in mind.
 
$\mathbb{R}^n$ can be a vector space over many different fields, but I would guess you are working with it over $\mathbb{R}$.
@Howcan
 
That's what I meant, sorry it's 4 AM.
 
No problem, just figured I should make sure I made that clear.
 
7:58 AM
So, $n$ linearly independent vectors would span $\mathbb{R}^n$?
 
Hi @infinitesimalsimplicio.
 
Hi pal @jas
@JasperLoy how's it going?
 
@infinitesimalsimplicio Not too good.
 
Hopefully not too bad either @JasperLoy
 
8:10 AM
@infinitesimalsimplicio Quite bad now. I made some "mistakes" which made things worse. I need to forgive myself.
 
Like I said, we all make mistakes my friend. Live and learn @jas
Those who don't learn will continue making the same mistakes...
...do you agree @jasp?
 
@infinitesimalsimplicio Yes.
 
Perhaps you can ask your doc to adjust your medication to the new situation @JasperLoy
Don't be too hard on yourself.
Christians say to error is human, but to forgive is Devine. Try being Devine to yourself @JasperLoy
Try to remember that you are your best friend.
 
Greetings
 
8:27 AM
Greetings
2
 
Greetings
2
 
Greetings
 
Greetings
 
Greetings
2
 
8:29 AM
Greetings
 
:-)
How are you doing all?
 
Combo breaker!
 
(-:
 
Huy
8:32 AM
(-:
 
@infinitesimalsimplicio When I get anxious, my OCD spreads to other things, things that did not affect me before.
Before you know it, it spreads to one, two, three new things and so on.
 
@JasperLoy that's the nature of the "beast" :(
 
@infinitesimalsimplicio Do you know how much I struggle every day?
@Chris'ssis I am not as handsome as him.
 
8:37 AM
@JasperLoy There is no success without so much struggle.
hehe, but it's not about that, it's about the message inside. ;)
 
@Chris'ssis But I am sure you are very beautiful.
 
@JasperLoy All girls are beautiful, isn't it? ;)
 
Our brains effect the entire body...and yes I do know what it's like to struggle against my pain.
 
@Chris'ssis No, only you, LOL.
 
@JasperLoy hahaha :-)
@JasperLoy By the way, is the medication you received effective to you?
 
8:40 AM
@Chris'ssis It helps a little. But these few days some "bad" things happened which made me worse, hard to describe what they are.
 
@JasperLoy Doing some sport might help you a lot.
 
You can't "embrace" chronic pain.
The kind of pain that makes you wish you were dead.
I have experienced it.
 
Which part?
I am going to chat and sort out my thoughts at the same time.
 
I think the message "don't kill yourself, we can help you" was bullshit. It shows a complete lack of understanding of what pain is. @jasp
 
8:49 AM
@infinitesimalsimplicio Well, he was trying to be encouraging. Are you in great pain now? Can I help you?
 
Talking about it makes it worse.
 
@infinitesimalsimplicio Physical or mental pain?
 
Both, it brings back the memories
 
I am sorry about your pain. I pray that you will find peace soon.
If you need to talk, I am here.
 
Thanks pal.
I wish I could (remove) them as easily
 
8:54 AM
Someone saw his wife being stabbed 18 times, and he then became delusional.
 
:-O
He must have needed meds to calm down
 
ADG
hi
hello @anon
??
 
 
1 hour later…
10:01 AM
I wonder if the mathematicians properly defined the falling factorials ...
I found some results in my work that suggest something is not properly defined.
 
10:13 AM
@Chris'ssis I am going to take a nap, hope my miracle comes soon.
 
@JasperLoy Miracles happen to those that believe.
OK.
 
hello
 
I believe. =)
 
@JasperLoy Good! :-)
@JasperLoy One moment ... You don't need to miss The imitation game movie ... too nice
 
hello @JasperLoy ,@Chris'ssis
 
@Chris'ssis can you help me on functional analysis
 
@Vrouvrou Not really. These days I'm only interested in integrals, series and limits, I work on a book related to them.
 
can i ask you the question
math.stackexchange.com/questions/1206617 @Chris'ssis if you have an idea
 
@Vrouvrou OK.
 
thank you
 
10:40 AM
@Chris'ssis I have arisen.
@Vrouvrou One generally does not ping random people to answer math questions in this chat. You can leave the question there and those who will answer will answer.
@Chris'ssis Did you see the line in my profile?
 
ok @JasperLoy i'm sorry
 
@JasperLoy hehe, good! :-)
 
@Vrouvrou If you are a grad student, I suggest you brush up on your undergrad studies. Your foundation is pretty weak which is why you have difficulty in later studies.
 
if you see that my question is easy give me an idea
 
I was referring to how you did not know about the 0 sequence yesterday, which is something pretty trivial.
That the only sequences in the naturals that converge to 0 are eventually 0.
 
10:51 AM
@vro where did you get the question from?
 
hhhhhhhhhh there is no relation
@JasperLoy
 
The thing is that when you cannot solve such simple questions, it is very difficult to move on to further studies @Vrouvrou
I am sorry if I sound rude, I just mean to help you @Vrouvrou.
 
i can solve very difficult questions,
sometimes i see very simple question and i don't know how to do
i think that's normal
@JasperLoy
 
@infinitesimalsimplicio from a paper
Landesman-Lazer conditions and quasilinear elliptic equations
 
10:54 AM
@Vrouvrou OK, but some of the questions you have asked here are extremely basic. I am just surprised. Anyway, please do not take offense. I mean well.
 
David Arcoya and Luici orsina @infinitesimalsimplicio
@infinitesimalsimplicio when p=2 it is simple we just hav to do u_n(u_n-u)=(u_n-u+u)(u_n-u) and apply the Cauchy schwartz inequlity
 
I have a question that I am not sure what is referring to
 
but my problem here is that |u_n|^{p-2}@infinitesimalsimplicio
 
You mean a research paper?
 
yes
 
10:57 AM
Have you tried overflow?
 
no
 
$X$ is our universe. Let $\{A_i\}_{i\in\Xi}$ be a family of sets in $X$ where $\Xi$ is a family of index.

Prove:
$$X\backslash (\cap_{i\in\Xi} A_i) = \cup_{i\in\Xi} (X\backslash A_i)$$
 
That's where the researchers are :-) @Vrouvrou
 

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