« first day (2464 days earlier)      last day (2558 days later) » 

1:02 PM
@Steamy oh right! that's true
 
@Astyx I am unable to do it. I just can't understand.
 
Did you understand what I said earlier ?
 
I know.
 
That does not answer my question
 
I didnt*
I am sorrry, I typed that by mistake.
I didn't understand what you said.
Am I supposed to find all possible combinations? That will take ages...
 
1:06 PM
You got what I meant by $m_0, m_1, \dots t_1, t_2, \dots $?
 
@Astyx I am wondering why there's no t0
 
Just because Mina is starting
 
and shouldnt it be this way: m0, t0, m1, t1, m2, t2
 
It doesn't really matter how you chose your indice
 
@Astyx Then why is there a t1
 
1:07 PM
Because I chose so
 
Can it be this way: m0, t1, m2, t3?
this will be easier right?
 
Yes but that would be confusing
 
That looks easier to me. '
 
Anyway if you want, say it's $m_0, t_1, m_2, t_3, \dots$
 
yes
 
1:09 PM
Say for $k\ge0$, each time $t_{2k+1} = 2$ then Mina choses $m_{2k+2} = 3$
And on the other hand $t_{2k+1}=3\implies m_{2k+2} =2$
 
@Astyx WHY?
 
Because Mina has a choice
 
How can you conclude this?
Both have a choice.
 
I'm exposing the strategy for Mina to win
 
oh .... but then Tina can choose whatever she wishes, if Mina chooses 2 she can also choose 2
 
1:11 PM
Yes
But that does not matter
 
@Astyx why :((((
 
So Mina can play in a way such that $t_{2k+1} + m_{2k+2}=5$ for all $k$, do you agree with this ?
 
yes
I agree, that she can play this way.
 
Now the goal for Mina is to get $m_0 + t_1 + m_2+t_3+ \dots + m_{2n} = 33$ for a certain $n$
Right ?
 
WHy m2n ?
 
1:14 PM
It has to be even
 
why?
Sorry, I am troubling you a lot :(
 
Because all the indices of $m$'s are even, I'll let you figure out why this is true
 
Ohkay but n can be even too
 
Yes
 
So please take n instead of 2n
 
1:16 PM
Fine
 
@Astyx Yes, all indices of m are even.
 
So you have $$m_0 + \underbrace{t_1+m_2}_{=5} + \underbrace{t_3+m_4}_{=5} + \dots + \underbrace{t_{n-1}+m_n}_{=5} = 33$$
 
Correct.
 
I'll let you go on from this
 
What do you mean?
I should do it independently from here, right?
Is that what you mean?
 
1:19 PM
Yes
 
Ohkay.
 
I believe you can do this by yourself
 
I'll try.
Just one question: DO I have to take all possible combinations?
 
No
 
Ok.
 
1:46 PM
Hi chat
 
Hi Fawad
 
@Astyx @Fawad hi
 
I need to learn notations like $t_n$ and $t_n+1$ ,$t_0$ . Can I know what I should search to get khanackademy video on it?
 
@Fawad they are just variables
if we use $a$, $b$, $c$, ..., we will run out of names soon
but the numbers can continue indefinitely
 
Anonymous
Where can I plot 3D graphs like plane and lines in 3D ?
 
1:48 PM
@LeakyNun but in physics it is used like at some "n" time like that
 
@blue geogebra
@Fawad could you provide some examples?
 
Anonymous
@LeakyNun oh checking
 
well, maybe those are just times, right?
instead of saying $t=a$, $t=b$, etc., we just say $t=t_0$ (initial time) and $t=t_1$
@Fawad I think you can't recognize me because I've discontinued my other account
I'm someone you know
 
Anonymous
@LeakyNun How? geogebra.org/apps is only showing a 2D cartesian plane
 
@LeakyNun the great duck?
 
1:50 PM
@Fawad no
@blue at the right hand side lives a button called "3D Grapher"
 
@LeakyNun then who are you? Whatsupman?
 
(I'm still not clear about SE's policy on double accounts)
@Fawad did you see that?
 
I didn't read,why deleted? Slow internet
 
Anonymous
@LeakyNun Oh got it! Great :D
 
@LeakyNun what the fun. I remembered you said you can gain too much rep with this account on math if you want. Good to see you
 
1:53 PM
@Fawad good to see you
 
At time $nT_0$ , the source emits it's $(n+1)^{th}$ crest and reaches the observer at time $$t_{n+1}=nT_0 +\text{some stuff}$$
Deriving Doppler effect here^ @LeakyNun
 
I see
 
I didn't know MSE would try to trick me with edit reviews
 
@Astyx lol,when you review at last it says "we were testing you" right?
 
Yup
Like adding : "Any help is holomorphic and much appreciated."
 
2:02 PM
hi chat.
 
@Semiclassical hi
 
@Semiclassical hi
 
@Astyx bonjour, ca me rend plaisir a te voir
merci pour effacer
 
Right. Glad to see you again :)
 
2:18 PM
@Astyx Is the answer 3?
 
Yes
 
One more question wrt your steps: How do you know that sum is always 5?
How does Mina know that sum should always be 5 for her victory?
 
She can play in a way such that the sum is 5, and thus has a winning strategy
 
How did you come to this Winning strategy?
 
because $\{2,3\} = \{5-2, 5-3\}$
 
2:20 PM
ohkay.
TY.
 
If for instance she had the choice between $1,2,3$, she should aim for $4$
 
Ok
 
Glad to help
 
what can the set of choices be, so that the player has a winning strategy?
does either player have a winning strategy if the set is, say, {1,2,4}?
 
Aim for 3 or 6 I guess
And something else
 
2:24 PM
"something else"?
 
That's not sufficient, I'm working on it
 
let's play that game.
would you like to start first?
 
Perhaps not on this chat
 
but it is related to math
game theory is a big topic in math
 
Yeah, but throwing out numbers would just be spam
 
 
2 hours later…
4:16 PM
Hi Ted
 
can we determine the multiplicity of an eigenvalue based solely on its characteristic polynomial?
i meant, the dimension of the eigenspace of the eigenvalue
 
You can get some information
 
0
Q: Determine weather a matrix is diagonalizable without knowing the matrix components

Avishay28I need to prove that A is diagonalizable when I already know this: A is 7x7 Rank(A) = 4 The characterized polynom is t^3(t^2-2)(t^2-5) Now I know that 0 is eigenvalue with both algebraic multiplicity and geometric multiplicity of 3, and I now that sqrt(2) is eigenvalue with algebraic multipli...

 
Yeah I just read that question too
What do you mean by multiplicity of an eigenvalue ?
 
@Astyx I clarified that in my prochain message
 
4:20 PM
Oh sorry I hadn't seen
The dimension of the caracteristic space associated to $\lambda$ is at most the multiplicity of $\lambda$ as a root of the caracteristic polynomial
 
In this case you know that the matrix is diagonalizable since every eigenvalue has the same algebraic and geometric multiplicity
 
@AlessandroCodenotti buongiorno
@AlessandroCodenotti how does one see that?
@Astyx oh heh
 
The multiplicity is at least 1 for both
And the geometric is always smaller than or equal to the algebraic
 
is "this case" referring to the question I linked to?
 
As for 0, the fact $rk(A) = 4$ means the kernel has dimension 3
Yes
 
4:23 PM
@Astyx oh, I'm stupid
 
So the only eigenvalue where multiplicities can differ is 0, but it has geometric multiplicity 3, so it's fine
 
@AlessandroCodenotti I thought that should be "larger than"
 
Nope
Take $A=\begin{pmatrix} 1&1\\0&1\end{pmatrix}$ for a simple example
 
Look up Jordan normal form for a deeper insight on this
Maybe not all of it
Actually more like Jordan-Chevalley decomposition probably
 
4:43 PM
Hi @Alessandro, @Astyx
 
Hi @Ted
 
What's up ?
 
Is there an example for a one-one functions that maps from set of all square integrable continous functions of the from (0,1) to \mathbb{R} to set of all square integrable Lipschitz continous functions of the form (0,1) to \mathbb{R}. I am curious and want to know any web references/clues
 
@Danu, @Balarka, (@MikeM, @PVAL): I've checked details on the spectral sequence. $d_2$ does in fact map the generator of $H^1(S^1)$ to the Euler class in $H^2(T_g)$. So we get $H^1 = \Bbb Z^{2g}$ and $H^2 = \Bbb Z^{2g}\oplus \Bbb Z_{|e|}$. Dualizing gives what PVAL deduced about $H_1$. There is torsion.
 
I had this pedagogy question : why is what we call maths in early classes mostly calculation ? Is maturity the only reason we don't teach children maths that doesn't need computation ?
 
4:46 PM
Perhaps Mike's construction gives the 2-chain in the circle bundle whose boundary is $|e|$ times a fiber.
 
@TedShifrin Yeah, I talked with PVAL earlier today. $\pi_1(T_1 \Sigma)$ is a $\Bbb Z$-extension of $\pi_1(\Sigma)$, but abelianization does in fact introduce torsion.
 
This was actually a really great question. And, along the way, Balarka and I "re"learned some basic alg. top. (thanks to Mike for the assist).
 
Me too. I wonder if I should do the spectral sequence computation for kicks.
 
@Astyx: There is a trend to try to get kids to think a bit more conceptually (not abstractly, necessarily). But many of the teachers can't handle it, and parents certainly can't.
 
Just to revise stuff.
 
4:48 PM
hi chat
 
You can do Serre on this, right? Monodromy should be trivial along the generator loops of $\pi_1(\Sigma)$ because the bundle is orientation, and restricts to torii along those.
 
I just thought it through in terms of the ÄŒech construction. It is the usual zigzag chase, @Balarka (for me, getting the curvature 2-form from the connection 1-form).
 
Ah right. It's one of those things that is how it is just because it's always been like this
 
says "hi Ted" before he can say hi to me first
Hi, Ted!
and Astyx, Balarka, Semi
 
Hi, DogAteMy :)
Did you ever pass along my even/odd thing? :D
 
4:49 PM
I did
 
@TedShifrin tfw you understand enough to know what's being claimed but not enough to understand why it's true
 
@TedShifrin bonjour/gu'n Tag/hello
 
@Ted I don't know those, though, just Serre spectral sequence.
 
@AkivaWeinberger hola
Feb 6 at 14:09, by Akiva Weinberger
…Guys, which one of you is Kenny Lau
yo mismo soy Kenny Lau
 
ok, gonna get dinner.
 
4:50 PM
It's the same spectral sequence, @Balarka, just a matter of how one understands it. For me it's a double complex with d going vertically and ÄŒech coboundary going horizontally.
 
Anagram, eh.
 
Bye, @Balarka.
 
@Semiclassical it was a joke in PPCG
 
Hi, @Leaky, whoever the h*** you are :)
 
4:51 PM
That helps me not at all.
(Not because of the German.)
 
@TedShifrin who would speak French and German with you?
 
That's the last time she asks for help like that, DogAteMy :D
 
Hey everyone!
 
I'm too busy in here to remember out of context, @Leaky.
Hi, Demonark.
 
4:53 PM
@TedShifrin and Spanish with DogAteMy?
 
Well, Jack Lee caught me in yet another bumble on main. It's pretty funny how that happens frequently.
@Leaky: You had a name which doesn't stick in my head. It's fine.
OK.
 
Oh snap!
 
I hate statistics.
 
@TedShifrin Just to check, am I right to think that you're talking about cohomology with integer coefficients? It's been a while since I looked at cohomology stuff so I may just be mangling things.
 
4:54 PM
Wao
 
Well, I'm thinking in terms of differential forms, @Semiclassic, but, yeah.
 
But yeah how's it going @Ted?
 
Okay.
 
What is meant by $f(x) = 10$ away from x=0
 
@LeakyNun So what do I call you? [DATA EXPUNGED], Leaky, or [REDACTED]?
 
4:55 PM
@AkivaWeinberger please delete the first one
 
I can talk about integral classes even using differential forms, @Semiclassic, and it's cool.
DogAteMy: Or just ignore him? :P
 
I vaguely know about that.
 
dat redaction action
 
Though I forget, integral in what sense? (When integrated along an arbitrary cycle?)
 
Don't delete the message, edit it to say (removed)
:P jk
 
4:56 PM
[REDACTED]
 
@AkivaWeinberger call me howsoever you like, provided that it is not [DATA EXPUNGED]
 
Any help
 
@TedShifrin nice suggestion
 
Ok @not [DATA EXPUNGED], but is that not a bit tedious?
 
All these multiple names and obsessions remind me of narcissism and you-know-who.
 
4:57 PM
@RajeshDachiraju Probably "if $x\ne0$, then $f(x)=10$"
 
@TedShifrin I'm sorry if I sound narcissistic.
 
@AkivaWeinberger then why the word "away"
 
What it reminds me of is this fiction site: scp-wiki.net
 
@RajeshDachiraju "Away from $x=0$" probably means "$x\ne0$"
@Semiclassical Indeed.
 
4:58 PM
probability?
 
back
 
how much sure are you
 
@Semiclassical SCP 1234-J
 
@Ted k let's see if I can compute SSS in a reasonable time or give up
 
4:59 PM
Hi @Ted
 
@RajeshDachiraju Pretty sure
 
Hey @Alessandro
 
@Ted is it the you-know-who I'm thinking about ?
 
ok thank you very much. makes sense and was helpful. I thought for existence of $m$ such that |x|>m it is 10
 

« first day (2464 days earlier)      last day (2558 days later) »