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02:00
I studied Russian for a year. No Hebrew.
ты говоришь по-русски?
The only times I've ever sought knowledge about the Cyrillic alphabet have been while trying to cheat at Geoguessr...and I forget what knowledge I obtain extremely quickly.
Да
Heya Fargle.
Howdy @Ted, rest of chat
Any more fun with Frenet?
02:02
who does alg.top here?
"does"?
Not for the moment; I've got financial math homework for tomorrow. Hopefully I can get to it more tonight though.
I learned Cyrillic at one point but it turns out that Russian doesn't actually have regular orthography
The 'o's have different pronunciations depending on context
What do you mean by regular orthography, DogAteMy?
02:03
@AkivaWeinberger it's more regular than English imo
@AkivaWeinberger depending on stress
rehi Antonios.
pre-stress o vs stressed o vs post-stress o
@TedShifrin i spent a long time in polland saying свиной салат томатный сэндвич to a lady in an airport trying to get a sandwitch on my way home from russia
not very irregular imo, you also get reduced vowels in English
02:04
hey russain was terrible mine also terrible and i didnt know the word for bacon
Polish ≠ Russian, Faust :)
her*
I mean, German consonants differ in pronunciation between blends and non-blends, and same for German vowels placed in diphthongs, but I'd still call its orthography regular because all those blends and diphthongs are regular (with possibly some exceptions)...
Hell if I know how to say bacon in many languages.
una curva (a curve, not a swear word :P)
02:04
@TedShifrin depends on what year we’re talking about sometimes
Arright so I guess I was mistaken
No, the languages are distinct, Semiclassic.
eventually say said something to the other girl working there in english
i was never so happy in my life
02:05
yay chat descends into linguistics once again
@Semiclassical Is there a combinatorial formula for counting the partitions of Poland?
3
I think that's an exaggeration, Faust.
she also got a good laugh out of it being BLT sandwitch that i wanted
@ÍgjøgnumMeg says someone whose name begins with a non-English letter
@TedShifrin i dunno i was pretty hungry
02:06
In any case I can now recognize loanwords written in Cyrillic
seriously, when I type @ your name comes up
How unfortunate
@Leaky: That's the only way to deal with these furryners.
@Fargle that’s pretty good
:^)
02:06
@Fargle just do a contour integral
and then divide by 2ipi
To quote Monty Python, "I've come for an argument."
@TedShifrin i finnaly know lineaar algebra so u cant make fun of me anymore :P
$b([w_0, \cdots, w_n]) = [b,w_0,\cdots,w_n]$
name shadowing much
If you say so, Faust.
I thought I knew linear algebra. Turns out I only know eigenvalues and eigenvectors, how embarrassing
02:10
Next you're gonna tell me I don't know linear algebra.
@TedShifrin you don't know linear algebra
Are there any other eigens
I am getting more senile ...
eigenpair :P
02:10
Well eigenspaces but other than that
@LeakyNun Eigenwhatnow
It's a German prefix, DogAteMy.
eigentlich
Eigenstates, eigenfunctions, eigendecomposition
@TedShifrin i may not be very smart but i do have an eidetic memory and im sitting at 98% in my seocnd linear algebra class so i have to know something about it
Also called proper or characteristic ... in English
02:11
@Semiclassical aka quantum mechanics
Or just "own"
I guess an eigenfunction is an eigenvector where the vectors are functions. What are the others? @Semiclassical
quantum mechanics is not maths
change my mind.jpg
@Faust: So you can do all the exercises in my books :)
eigenbasis, DogAteMy :)
02:11
Oh is an eigendecomposition when you break a space into eigenspaces?
In QM you talk about state vectors
Although I've never used that word.
@TedShifrin well i can do and have done all the excercises in the first 6 and 8th chapeters of sheldon axlers book so im sure i can at least do some of them...
And an eigenbasis is a basis made of eigenvectors. And with symmetric matrices you get orthogonal eigenbases.
02:12
@TedShifrin do u have a recommendation for an introductory text on topological dynamics?
> a chain homotopy between the identity map and the zero map on the augmented chain complex $LC(Y)$
say what
So if said state vector is an eigenvector of a given operator, we call it an eigenstate
@LeakyNun I need a brain transplant. Change my mind
Nope, @JoeShmo. I only did dynamical systems in grad school. Nitecki's book might have some of what you want.
@AkivaWeinberger mind=brain?
you should make that a meme though
02:14
@Semiclassical you making stuff up ?
@LeakyNun mind${}\approx{}$brain
never heard of an eigenstate
is it the capital of the eigenvalues?
02:15
...
Booo
@LeakyNun Yay
@BalarkaSen cc
@Semiclassical sorry on alot of morphine please define?
No, @Faust, it means you live in one of the eigenspaces.
isnt that just the definition of an eigenspace
everything in an eigenspace lives in that eigenspace
02:16
It's a term the physicists use.
Is the German for eigenvector "eigenvektor"
doesn't it get used in Markov chains?
@Akiva Yes
@TedShifrin it all makes sense now
@ÍgjøgnumMeg Cool, I think this means I speak German now
02:17
Ein Eigenvektor einer Abbildung ist in der linearen Algebra ein vom Nullvektor verschiedener Vektor, dessen Richtung durch die Abbildung nicht verändert wird. Ein Eigenvektor wird also nur skaliert und man bezeichnet den Skalierungsfaktor als Eigenwert der Abbildung. Eigenwerte charakterisieren wesentliche Eigenschaften linearer Abbildungen, etwa ob ein entsprechendes lineares Gleichungssystem eindeutig lösbar ist oder nicht. In vielen Anwendungen beschreiben Eigenwerte auch physikalische Eigenschaften eines mathematischen Modells. Die Verwendung der Vorsilbe „Eigen-“ für charakteristische Größen…
@Akiva you are as fluent as one needs to be
It should understood properly as eigen-“state vector “
What kould go wrong
@AkivaWeinberger -,-
02:18
But that’s a mouthful so we often omit the word vector
Given that the dim(imT)=1 prove that T is nilpotent or diagonalizable @TedShifrin how few lines can you do this in?
@Faust: I assume you're using Jordan canonical form over $\Bbb C$?
you dont technically need to use JCF
but you can
You didn't say $T\colon V\to V$, by the way.
But those adjectives only make sense in that setting.
$T \in \mathcal L (V)$
02:21
I want an eigeneigenvector
As I said.
I don't know how but I want one
DogAteMy: You're an eigenpainintheass.
10
Oh, the mad starrer is back.
No, I think whoever starred that knows what they're doing
You do make me laugh, DogAteMy.
Well, I need to leave ... Bye, all.
02:23
night
Eh, that’s not hard. Start with a set of eigenvectors for a certain operator and construct an operator which permutes then
If that operator leaves one of the eigenvectors fixed, that’s an eigeneigenvector
dim(imT)=1 hence $dim(kerT^n )= $n or n-1 if n then T is nilpotent if n-1 then $ V= G_0 \oplus G_{\lambda} $ but by assumption we have that $G_0(T)=E_0(T)$ $dim(G_{\lambda}) =1 $ hence $ G_{\lambda}=E_{\lambda} $ the result follows
@TedShifrin
peace ^^
@Faust Let $v$ generate $\operatorname{im} T$. Let $Tv=\lambda v$. So $T^2 = \lambda T$. If $\lambda = 0$ then $T$ is nilpotent. Otherwise, its minimal polynomial has distinct roots, so it is diagonalizable.
very good
thank you, master
02:29
who is dogatemy
Morning ninja sheep
anyone klnow farey sequence?
the sequence of rationals?
uh its a subsequence of the one your thinking of probally
$F_n = \frac{a}{b} $ s.t $a\leq b \leq n $ and non negative
integeres
02:32
who is ninja sheep?
the one your thinking of probally allows a bigger then b
@nitsua60 is ninja sheep
Show that the number of elements in the Farey sequence $F_N$ is $1 + \sum_{n \leq N} \phi (n) $
where $\phi (n) $ is euler toteint function
any idea how to prove?
@AkivaWeinberger you don't know a language without knowing how to swear in it
Arschloch
I consider knowing how to swear in a language as a necessary and sufficient condition for one to consider themselves proficient at it
perfekt
02:37
@Faust (shh... you blew my cover. Leaky Nun didn't even know I was here.)
@TheTestosteroneFanatic good to know im proficient at japanese then
lol
@nitsua60 you keeping busy?
Wichsteufel?
@Faust Like a one-legged man in an ass-kicking contest, as my dad would say.
לך תזדיין
02:39
hope you have something to sit on...
baka, aho , hmm
they dont have alot of swear words in japanese
@Faust $\phi(b)$ just counts the number of reduced fractions with $b$ as the denominator
theres some racial slurrs but im assuming those dont count
Tu madre era un hámster y tu padre olía a bayas de saúco.
0
A: Direct ceiling proof

Kenny LauUse this alternative definition of ceiling: For $x \in \Bbb R$, $\lceil x \rceil$ is an integer $n$ such that: $x \le n$, and for every other integer $m$ such that $x \le m$, we have $n \le m$. To show that $\lceil x \rceil + n = \lceil x + n \rceil$, I will show that $\lceil x \rceil + n$...

lol
wrong language
02:41
i.e. UMP
@AkivaWeinberger ^
@LeakyNun why does that not seem obvious? (maybe its the morphine but im not seeing why that obvious)
@Faust then you can answer that :P
@LeakyNun Added a small and possibly unnecessary comment for the benefit of the OP
@AkivaWeinberger but category theory :/
seriously, category theory gives me insight into so many things
02:45
What does the question have to do with category theory?
@Faust Maybe he just wants a more rigorous proof than "it's obvious". (Also: morphine?)
I mean, phrasing things in terms of UMP gives me insight on how to prove it
What's UMP
Ultimate Mega Pinball
@Faust why the morphine?
Escaped from the hospital less than 24hrs ago and still really sick
"Escaped"?
02:47
Universal mapping property
escaped? So the doctors are out there looking for you?
Ah. Huh? @Daminark
Also I really want Universal Mega Pinball to be a thing
Well the didnt want me to leave but they said they wouldnt do anything unless i got worse so i came home to do math...
i was there for 10 hrs and they did like half a dozen tests on me and came to the conclusion i was unlikely to die
In various branches of mathematics, a useful construction is often viewed as the “most efficient solution” to a certain problem. The definition of a universal property uses the language of category theory to make this notion precise and to study it abstractly. This article gives a general treatment of universal properties. To understand the concept, it is useful to study several examples first, of which there are many: all free objects, direct product and direct sum, free group, free lattice, Grothendieck group, Dedekind–MacNeille completion, product topology, Stone–Čech compactification, tensor...
at least not in the immediate future
if i get much worse ill go back
02:48
I guess I need to be the change I want to see in the word [looks up how to build an arcade cabinet]
Oftentimes you define objects as the unique ____ satisfying ___
And then give a construction to show such a thing exists
is there really a more general word for object?
@Faust what's the diagnosis though?
So how does that relate to $\lceil\ddot\smile\rceil$?
(Or Ultimate Mega Pinball)
Field of fractions of a ring R, for example, can be defined as a field with an injective homomorphism from R into it such that any other injective homomorphism factors through it
02:51
Mhm.
How to solve $13x\equiv 1\ (\textrm{mod}\ 2436)$ quickly?
@TheTestosteroneFanatic the diagnosis is they have nfi whats wrong with me and i need to see a GI specialist and have an endoscope to figure out whats wrong with me, but abdominal pains not enough for that to be an emergency in my country you must also vomit blood which i havent done yet so technically in my shitty country i have to wait to see a specialist for 1-8 months
Well that's what UMP stands for, but it also stands for ultimate mega pinball
So that's the relationship
at least not if your red count is close enough to normal and you have CT showing its not your appendix or bowel blockage
@Niing Well 13*187=2431
Don't know if that helps
$13(187)\equiv-5\pmod{2436}$
02:54
@Faust best of luck! Might I suggest getting a Candida test?
actually you could do that at home
And then $2435$ is a multiple of 5
Candida test? from what im told its probally uclers
so 5*487=2435 so $5(487)\equiv-1\pmod{2436}$
@Faust it could be, but the Candida test is so simple to do right at home, I'd say it's worth trying it
so $13(187)(487)\equiv-5(487)\equiv1\pmod{2436}$
I guess I got kinda lucky there
akiva what does degenerate mean ?
in plain english
$(187)(487)=91069\equiv937\pmod{2436}$
so unless I messed up the answer is 937 @Niing
@KasmirKhaan What's the context?
A dot X = 0 for all X in K^n , then A=0
I mean the word degenerate what does it stand for :D
that property btw is called non-degeneracy
I dunno why it's called that
02:59
okay thanks anyway :D
In geometry, a triangle with a side of length zero or an angle of length zero is called degenerate
'cause it's not really a triangle
Degenerate means immoral or corrupt or not containing a desired property
but it's like a limiting case of triangles
It's like a case where the definition breaks down
hmm
thanks guys :D
I remember now we used this defintion to call a triangle degenerate
when it is a line
but here its about the dot product
there is a positiv definite for reals
but if we consider our field C
03:02
~ AkivaWeinberger: thank you!
we can get A dot A to be 0
without A being 0
well no
thats iff
A dot A=0 iff A=0
thats a definition of an inner product space
dot this vector with itself faust!
(1,i)
what you said holds for reals only not for complex :D
think an inne rproduct is defined diffrently to get the length
Am gonna go ahead and call you faust7 for the rest of the week untill you say something better than that :D
03:06
whats the length of i?
why think of geometric meaning?
my confusion is your using the real inner product for a complx inner product
there nto the same
not*
how do you describe a limit point formally / with logic/
the operation is defined diffrently as a require over any field is that <v,v>=0 iff v=0 over any field
trying to say something like "a point for which any neighborhood/ball you make around it will contain at least one point in S"
03:08
so the opertation your using isnt an inner product...
no it is
just we consider the field K to be Complex numbers
nothing stops us from doing that
A dot A >= 0 is not an universal fact
just for reals its true
x is limit point if for any ball centred at x of radius epsilon s.t epsilon >0 contains infinitly many points of the sequence. @user525966
but then what is "contains"
Notice that one point is not sufficient you must have infinite
@user525966 x is a limit point of S if for every $\epsilon > 0$, you have that $S\cap B_{\epsilon}(x)\setminus \{x\}$ is not empty
03:10
In $\Bbb C^n$, $x\cdot y$ is defined to be $x_1\overline{y_1}+\dotsb+x_n\overline{y_n}$
or is it the other way?
Whatever, the point is we change the definition so that $x\cdot x\ge0$
@AkivaWeinberger thank you
and this is more convenient I guess
I feel like these definitions become circular though
there is anthor way byt the parallelogram law but thats the normal one
How is that circular?
03:11
I don't know what you do in more general fields.
Like what is B(x) really
An inner product is just a map satisfying certain properties. If the map you use doesn't satisfy those properties then it isn't an inner product, what's the problem?
@user525966 it dpends how many dimensions your in
in two dimensions its just an interval
i'm sticking with 2 for now, real number line
$B_{\epsilon}(x) = \{y: d(x,y) < \epsilon\}$
03:13
then its just an interval around the point of length 2 epsilon
$(x-\epsilon, x+ \epsilon) = B_{\epsilon} $
So $x$ is a limit point if $S \cap \{\forall \epsilon > 0, \forall y: d(x,y) < \epsilon\} \setminus \{x\}$ is nonempty
For all $\epsilon$, yes. And you mean \setminus $\setminus$
if you mean removes then yes
I actually meant epsilon, I don't know why I wrote x
I need to go to bed
I don't know why I'm up
updated definition, is that more accurate?
03:16
it is also equivlent to say that any epsilon>0 radios around the point must contain an infinite number of points of the sequence.
@Akiva so inner products usually carry a notion of being positive definite, which needs an ordered field. In the complex case you kinda sidestep it because you have conjugate with its properties, so I guess you'd want a field that's either ordered, in which case you do the R thing, or you want to have some subfield and something like a conjugate
Sorry
@user525966 $x$ is a limit point if, for all $\epsilon>0$, the set $S\cap\{y:d(x,y)<\epsilon\}\setminus\{x\}$ is nonempty
There's a nicer way to say it if you're writing out the definition of the ball
03:17
empsilon
epsilon
not y lol
$d(x,y)$, incidentally, means the distance between $x$ and $y$ (so $|x-y|$)
$x$ is a limit point of $S$ is for all $\epsilon > 0$, $\{y: 0 < d(x,y) < \epsilon \}\cap S \ne \emptyset$
does it matter that we're putting forall y out front?
@Daminark Same thing
You don't need that, the set of y such that blah
03:18
@user525966 It doesn't actually make sense if it's in the set builder notation
@AkivaWeinberger I was zooming in on the use of "for all y", the part about >0 was my being lazy to write \setminus x on a phone
$x$ is a limit point if, for all $\epsilon>0$, the set $S\cap\{y:d(x,y)<\epsilon\}\setminus\{x\}$ is nonempty
^Should be free of typos
Like isn't $\{y:$ the same as $\{\forall y:$?
x is a limit if for all $\epsilon >0 $ then the set $ S \cap \{ y:d(x,y) < \epsilon \} \backslash {x\} $ is nonempty
I wrote "for all $y$" before, I meant "for all $\epsilon$"
03:19
wtf
actually since I am dealing with $\mathbb{R}$ I should be more precise
@user525966 $\{y:$ means "the set of all $y$ such that"
w.e akiva has it written down correctly
I don't think you can put a logical symbol like "$\forall$" (for all) in the bit before the colon
Vague convergence: when weak-$\ast$ convergence just isn't sexy enough.
03:21
I think it's possible you can though
but it is also true that for any $\epsilon >0 $ there exists N s.t the sequence $(x_n) $ is contained in $B_{\epsilon}(x)$ for all n>N so its not just non-empty its actually has an infinite number of points
sort of like how forall x is used in delta epsilon proof
it is for all x but vacuously true outside of 0 < |x-a| < delta
In any case, suppose I choose an $\epsilon$, and you're tasked with finding an element of $S$ whose distance from $x$ is less than $\epsilon$. If you can always succeed, no matter what $\epsilon$ I specify, then $x$ is a limit point of $S$.
(ultimately I am trying to prove that the complement of an open set must be closed)
but you dont need to prove theres an infinite number but it can be useful in proving other things that this is true
03:23
for instance does it make sense to say that a set is open if $\forall x \in S, \exists \epsilon > 0 : x+\epsilon \in S \land x-\epsilon \in S$
@Faust I think technically it is, at least according to mathworld
but its not mutually excluive
exclucive
just cause the set is open doesnt mean the compliment is not open
@user525966 You probably want something like, $\forall x\in S,\exists\epsilon>0,\forall a<\epsilon:x+a\in S\land x-a\in S$
whats the definition of open set you use?
it should be that hard
shouldnt*
a set is closed if all limit points are inside S, right? Then that means any point touching S's complement must be fully inside that complement, which is an open set, no?
I'm going to bed now. Bye
03:26
gnight akiva
it depends on what you know do you know connectedness?
ok
are you workign in R or R^2 etc?
whats your definition of being open?
@Niing extended euclidean algorithm
03:30
(this proof can range from very trivial to somewhat hard depending on what your allowed to use)
for example R is closed closed remove open is closed so R remove S is closed but thats precisely S compliment
@user525966 no, you can't
to using the definition of open
and psuhing it through theat argument
my defintion of open is its compliment is closed
but i do mostly topology not analysis
if your being asked such a question you use a different definition of open
An open subset of R is a subset E of R such that for every
x in E there exists $\epsilon > 0$ such that $B_{\epsilon}(x) $ is contained in E perhaps?
sometimes E is open if E = int E is also used...
anyway just take an arbitrary limit point say x then every ball around x contains something in S and something not in S but then that point is not in S since S is open but it is in R so its in R remove S (since it not in S ) this was an arbitrary limit point of S so every limit point of S is in R remove S or $S^c$ so it is closed. @user525966
@Secret !
how is you?
As usual
O.o
enjoying skool?
03:45
Uni is as usual, nothing very special
secret special!
pf: not very many nice people in world and secret nice so special by transitivity Q.E.D
sorry had alot of morphine today O.o

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