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16:03
@N3buchadnezzar are you sure that is not backwards? unless $x_{\text{min}}=0$ that would preclude $0$ from $M$.
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@robjohn It is probably backwards, but it still seems strange. If M is huge then i guess it is possible that $\|x - x_\text{min}\| > \|x_\text{mini}\|$.
@N3buchadnezzar no it is not, I was forgetting that $x_{\text{min}}\in M$
Good evening!
... ? =(
@N3buchadnezzar wow XD
16:07
@N3buchadnezzar Wouldn't the $x$ with minimum norm do the trick?
@N3buchadnezzar your circle is perfect! :D
@robjohn The first part of the problem is fine, I know from banach that such a minimal vector exists. The problem is the next part.
@Nimza Magic!
@N3buchadnezzar which part?
$\text{Re} \left(x_\text{min},\,x_\text{min} - x\right) \leq 0 \qquad \forall \ x \in M$?
@robjohn Yes
In order to do so I got a tip that I need to use
$$ \| x_\text{min} + t (x - x_\text{min})\|^2 \geq \|x_\text{min}\|^2 $$, but like I said. I do not understand why the inequality holds.
Ah, I see! I understand now why, but unable to explain it, Hmm
I am so stupid!... Too much work today
@N3buchadnezzar I am writing something up, should I stop?
@N3buchadnezzar $$(x_{\text{min}}-x,x_{\text{min}}+x)\le0$$
$$(x_{\text{min}}-x,x_{\text{min}}-x)\ge0$$
Subtract
16:22
@robjohn Thanks, I was able to prove it. I am lucky to have a blackboard behind me
@Charlie Hello, Marilia!
Hello AA!!!
@Charlie hehe, how are you?)
@Charlie!!!!!!!
@Nimza fine. you?
16:31
@JayeshBadwaik Hi!
@Nimza Hi man!!
@JayeshBadwaik jayesh!!!!!!!!!!!!!!!!!!!!!
@Charlie too!)
@Nimza Wassup? Any progress on that local fractional thing?
@JayeshBadwaik ah, no :( Only got recommendations
16:33
@Nimza Ohh. :-(
@JayeshBadwaik how are you?)
@Nimza I'm good. Starting reviewing up for my entrance test one month from tomorrow. For starters, reviewing up algebra.
@robjohn So I end up with $$\text{Re}\langle x_\text{min} , x - x_\text{min} \rangle \leq - \frac{t}{2} \| x - x_\text{min} \|$$
@JayeshBadwaik entrance test?! where are you trying to enter?
Since $\|x - x_\text{min}\| \geq 0$ and $ t \in [0,1]$ this proves that
16:36
@Nimza a master's program in mathematics.
$$ \text{Re}\langle x_\text{min} , x - x_\text{min} \rangle \leq 0$$
as wanted. =D
@N3buchadnezzar cuil.
@JayeshBadwaik aaa!
@Nimza yeah....
@JayeshBadwaik yay
16:39
@Charlie woooo....
Howz your day? Did you get that stat thing from yesterday?
@N3buchadnezzar So you can draw circles, but straight lines elude you?
@JayeshBadwaik yes...i think idid..but there was a few datas that were wrong and i coild not fix...
@Charlie ahh.
@JayeshBadwaik Yes?
@N3buchadnezzar Hmm, nothing, its opposite with me. :P
"Linear differential equations are used to motivate the introduction of eigenvalues and eigenvectors, but this motivation can be skipped." --Petersen

I love when we can skip the motivation. I have had enough of it already!
@JayeshBadwaik you? How are you? Read yoir mails.
@JayeshBadwaik yep me too
16:45
@Charlie Well, I'm now better. I still haven't got the proof of perron-frobenius thing. Haven't looked at it actually. I understand the proof now though, still somewhat edgy I think.
@JayeshBadwaik hmm
Hmm if you had to describe some interaction between euclidean polygons, points, vectors, and lines, what would be your preferred notation for defining these things?
@skulll greetings!!!
Hi @Charlie how are you?
Good.you?
16:58
Fine thanks :)
17:15
hi
17:31
@jdoe wassup?
nothing really just having tea
@jdoe iced?
no
can I make iced tea myself?
Of course!
i would like to try that
17:35
It's easy
I'm stuck on combinatorics
Share it...if i can help
@jdoe?
@Charlie jdoe routinely gets kidnapped. (quoting Willy)
17:55
@JayeshBadwaik yeah jay jay :P
1
Q: Automorphisms of $\mathbb{Z}_2 \times \mathbb{Z}_2$

CarlyOkay so I need to compute an automorphism on $\mathbb{Z}_2\times\mathbb{Z}_2$ using the fact that if $f\colon G\to H$ is an automorphism and $G=\langle K\rangle$, then $f$ is determined by where it takes members of $K$. I think that $\mathbb{Z}_2\times\mathbb{Z}_2 = \langle(0,1),(1,0)\rangle$ u...

it's not automorphic forms!
someone should remove t he tag
@jdoe: I did
18:12
@jdoe ahh.
@mk, thanks
@Charlie this song still makes my skin tingle.
@skullpatrol This song was on the top of the charts the day I was born.
@JayeshBadwaik What do you think of it?
@skullpatrol Nothing compares to that song.
18:37
hello everyone
hoa ]
how are today?
Fine thanks. How are you?
very bad!!
18:40
I failed the exam :D
poker face
*Let n be the smallest natural number that cannot be defined in fewer than 20 words.*

**Since this sentence itself contains fewer than 20 words, it is paradoxical.**
But the sentence is not talking about itself, it's talking about a number.
@skullpatrol do you about the troll (like a boss, troll face and forever alone)
@GustavoBandeira, it's an impredicative definition
does anyone know about a book for primitive function and derivative
18:50
@pourjour Specifically?
@pourjour Piskunov's calculus has a good compendium of primitives, IMO.
the basics
(IMO) stand for what
@pourjour "In my opinion"
yes
ok
Hello, does exist sharply increasing sequence which have limit an same as limit 1/an ?
@PeterTamaroff is it russian
18:55
@pourjour It is.
Hey, I just made an account
and I am lazy! But here is my
homework. So do it for me maybe?
@user1097772 You're looking for a strictly monotone sequence for which $\lim\;a_n=\lim\;a_n^{-1}$?
Only solution I can imagine is an = {1} if its possible set the sequence finite.
@user1097772 Well, you merely want $\lim a_n\lim a_n=1$, right?
So you need a sequence which is strictly increasing towards $1$.
I can think of $1-\dfrac 1 n$ off my head.
19:00
@JohanLarsson very smooooth...
I wish I could contribute with something math-related tho
But you guys seem to write music a lot
@JohanLarsson Btw to "write music" or any other link you may use this format: [title](URL link)
sorry somebody switched off my comp :/
If strictly monotone means that for n1, n2: n1<n2: an1 < an2 than yes, and the limit is ok
sorry for my english
@skullpatrol broken link, write music as in talk music on a chat (got it about link)
i want liman=lima−1n?
1-1/n is fine, thanks a lot :) and not I haven´t maden my account few minutes ago. And I tryed to solve it but, I went wrong way, so thanks :)
@pourjour Which exam did you fail?
38 mins ago, by pourjour
I failed the exam :D
@skullpatrol maths
@jdoe Tell me more.
@pourjour What part of maths?
19:21
@GustavoBandeira You have not defined the number, you have merely stating its existence.
There is a difference between construction and existence.
What would be the construction then?
@GustavoBandeira What are you trying to invent now?
@PeterTamaroff Invent? But I never invented anything.
@skullpatroll series continuity and a limit we must use rigorous way to solve those exercises the old one
@GustavoBandeira Well, you should. Just avoid anything wingish,
@pourjour Huh?
19:23
funny yeah
@pourjour Yes, when they want it done rigorously that means a lot of memorization.
@PeterTamaroff wingish?
the bastard give us just two hour to finish 5 exercises 3 of them are very hard
@GustavoBandeira Avoid wings.
@pourjour You have to recall and recite very quickly.
19:28
@skullpatrol yep that's my weakness (very slow to find solution)
@pourjour It is everybody's weakness, and they test you on how well prepared you are to work quickly.
@skullpatrol I prepared very well whoever he give us some exercises I never saw them
@PeterTamaroff Hey, mind helping me finding the convergence radius of a power series? =)
also I don't believe in my abilities cert
@N3buchadnezzar Let's see.
19:33
especially if there is no times at the exam
I know I have to differentiate twice and do some black magic, but I cant for the life of me iron out the details
@pourjour Well, you have seen them now and he will not fool you again on them :)
$$ \sum_{n=2}^\infty \frac{n(n+1)}{4^n} (z-2i)^n $$
@skullpatrol next exam will be the same thing
@N3buchadnezzar Well, what did you get?
19:36
@pourjour Ask him for practice questions or look for old exam questions.
@PeterTamaroff I tried starting with $z^n$ because the sum of this is know as long as $|z|<1$. Differentiating twice yields. $n(n-1) z^{n-2}$. Now one can use $z=z-2i$, and then...
@skullpatrol yeah I did but in vain
My index for $z$ is wrong though =(
@N3buchadnezzar Your power series is of the form $a_n(z-a)^n$
Now, I would personally find its explicit expression.
@pourjour Keep looking for old exam questions and look in other books too.
19:39
@skullpatrol I use workbooks
Consider $$f\left( z \right) = \sum\limits_{n = 0}^\infty {\frac{{{{(z - 2i)}^n}}}{{{4^n}}} = \frac{1}{{1 - \frac{{z - 2i}}{4}}}} $$
@pourjour Try going to the library math section and looking there for similar questions.
@PeterTamaroff Thanks, just what I needed.
I think I need to go home from uni soon, it is almost 21:00 here.
Then $$f''\left( z \right) = \sum\limits_{n = 2}^\infty {\frac{{n\left( {n - 1} \right){{(z - 2i)}^{n - 2}}}}{{{4^n}}}} $$
Changing some indices gives $$f''\left( z \right) = \sum\limits_{n = 1}^\infty {\frac{{n\left( {n + 1} \right){{(z - 2i)}^{n - 1}}}}{{{4^{n + 1}}}}} $$
@skullpatrol huh there is no cool library here only rubish with old useless book have no relation with maths
19:43
@PeterTamaroff I think your limits are wrong here
and then $$(z - 2i)f''\left( z \right) = \frac{1}{4}\sum\limits_{n = 1}^\infty {\frac{{n\left( {n + 1} \right){{(z - 2i)}^n}}}{{{4^n}}}} $$
@N3buchadnezzar Nope. The first two terms are $0$.
@PeterTamaroff Oh, clever.
@pourjour Ask your teacher what to do.
I think i will just try to controll the time that's all and a cigarette will help to be fast
@pourjour Never be too proud to ask a teacher what to do :)
19:48
@N3buchadnezzar Just a derivation. In general, if $$f(x)=\sum_{n=0}^\infty a_n(x-a)^n$$ then $${f^{\left( k \right)}}(x) = \sum\limits_{n = k}^\infty {\frac{{n!}}{{\left( {n - k} \right)!}}{a_n}} {(x - a)^{n - k}}$$
@skullpatrol he doesn't help I tried but I don't why he just told me use workbooks
@pourjour Then he's playing the old game: I have a secret, and you have to try and find out what it is.
Note that letting $x=a$ one gets the famous $$f^{(k)}(a)=k!a_k$$, that is $$\frac{f^{(k)}(a)}{k!}=a_k$$ which means an absolutely convergent series over some disc $|z-a|<|w|$ coincides with it's Taylor series there.
20:11
Am I write if I say that every decreasing sequence is limited from above?
Hence the sequece which is decreasing and isn't limited from above doesn't exist?
@user1097772 you mean "right"?
*right
@user1097772 you can edit the message
if you pass your mouse in your message you'll find a triangle, click "edit"
within 2 min
@skull :D
@Charlie :)
@skullpatrol wassup?what are you doing?
20:15
@Charlie Listening to music right now, what did you think of the song?
@skullpatrol nice, nice.
@skullpatrol yeah, i read
@Charlie thanks for advise, but it's probably to late for edit ..
@skullpatrol can I be honest?
@Charlie Yes.
@skullpatrol Think it's a little boring...
20:19
@Charlie I agree.
@skullpatrol but you said you skin tingles...
@Charlie The tingle wears off.
@skullpatrol hehehe
Oh, I have a riddle!
20:22
@skullpatrol you lost the thrill of liviing?
@N3buchadnezzar i like riddles
Say there are three boys, who share 7 bottles filled with milk, 7 empty bottles, and 7 bottles half filled with milk. How can they share such that they each get the same amount of milk? If they do not have to have same amount of bottles each, are there more solutions?
@skullpatrol you showing me some boring songs today, skull...what's going on?
Hold on to 16 as long as you can
Changes come around real soon
Make us women and men
Oh yeah, life goes on
@N3buchadnezzar that's not a riddle... i prefer Riddler's type of riddle....
20:28
@N3buchadnezzar what the heck does that song mean?
looks like selena gomez
@N3buchadnezzar i don't think...
@JayeshBadwaik The song that was on top in my birth date is "Please don't go". Curious, isn't it?
@Charlie Is this better?
20:36
@skullpatrol MUCH BETTER
@NIMZA !!!
@CHARLIE! Marilia = Maryl?
@Nimza I think it's Marilyn
@Charlie m :)
So the unicorn likes rock aye?
I find it dissapointing that you do not like ALL THE MUSIC ^^
@Charlie there is some problem with connection at my side :( I've found russian Marilia in the internet: Лабецкая Марилия Викентьевна
20:41
The doors - Riders on the storm
Uriah heep - Lady in black
Deep purple - Stormbringer
Rolling stones - PAint it black
and so forth
@N3buchadnezzar excuse me?
@N3buchadnezzar I love rock, man
Like... I listen to black metal, swedish pop, rap, hip hop, dubstep etc..
@Nimza what does mean the left and right words?
@N3buchadnezzar if a song is good i listen.
@Charlie ah, full name in russia consists of 3 parts: name, surname and father's name :) Her father is Vikentij
@Charlie Heard of the songs I listed? They are awesome rock songs from the 70ties :D
20:45
@Charlie How is this?
@Nimza Fascinating!you should use your name, real name.
@N3buchadnezzar of course
@skullpatrol ohh..shivers!!!!
@WillHunting heyyyy!!!
@Charlie why?) You too then)
@Nimza your name is cool!
i have a few prof from russia in my uni
i like their last names :)
@Charlie In my university there are only soviet profs :P
20:49
@Nimza hahahaha here there are people from china, russia, germany, greece, and other places
@skullpatrol IT'S THE BEAST UNDER YOUR BED, IN YOUR CLOSET IN YOUR HEAD
@Charlie and all lections are in english?
@Nimza In portuguese, but with accents
@Charlie uh!
@PeterTamaroff: yes?
20:53
@skullpatrol here sandman is called "Zé pestana"
child is seen reciting a prayer while being watched by Sandman.
@PeterTamaroff I will look at it when I finish my lunch :-)
@robjohn Eat well.
@skullpatrol yes!
@Nimza So, will you use your name, AA?
20:56
@Charlie mmm, here is another guy with the same name) we may collide!)
@Nimza the whole name is equal?
@Charlie no, only A...y :))
@Nimza hmm does anybody else know your name?
@Charlie no, only you, Il y a and Jonas) I think

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