#serious-discussion

1 messages · Page 515 of 1

alpine kindle
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I'm eigenstuff

brave hollow
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I thought this was standard

bright hill
#

eyyy

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it's nyann

brave hollow
#

'ello mate

alpine kindle
#

yo

bright hill
#

ello

fair mural
brave hollow
#

I actually dmed you not so long ago darq

long matrix
#

matrices in infinite dimensional vector space thonk

bright hill
alpine kindle
#

OMG ARTIN USING COMM DIAGRAMS

fair mural
fair mural
light needle
#

over relying on matrices is not good

fair mural
alpine kindle
#

matrices between vspaces of different base fields thinkies

long matrix
alpine kindle
#

oh wait

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nvm I'm stupid

inner finch
#

math moment

alpine kindle
#

this happens to me all the time

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i talk too much

sleek wing
alpine kindle
sleek wing
#

omg I would like the 5 lemma please

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hahah the fuckin 16 theorem as well

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wait why do I know what these are now

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what's happening to me

fair mural
#

from me looking at wikipedia for 2 minutes it seems that these lemmas are defined only for square numbers

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explain the 5

bright hill
#

is there any kind of crack which you can survive on 500 g?

fair mural
#

depends on your tolerance

sleek wing
#

that's like

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a whole page of diagram chasing lmfao

frozen merlin
#

there's a thing on the 3b1b blog with like puzzle pieces

light needle
#

i mean its a diy type of deal

frozen merlin
#

wait this is snake not 5

sleek wing
#

5 lemma is on the left

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kind of

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a weaker version of it

long matrix
frozen merlin
#

yeah I don't think this article has 5

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it seems cute but I can't appreciate it without actually learning the stuff first

fair mural
modern geyser
fair mural
#

oog

alpine kindle
#

is there a study of solutions to multivariate exponential equations (including trig and stuff)

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like how alg geom is for polynomials

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because the graphs look really cool

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like this

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and this

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i wonder if we can say anything about the structure of these solution curves

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also whatever the hell is going on here

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there are too many interesting ones

fair mural
#

my entire latex document died because i forgot to close some parentheses

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actually cringe

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i was freaking out trying to find the error for like 5 minutes

median zinc
alpine kindle
#

🫂

alpine kindle
rocky shuttle
frozen merlin
rocky shuttle
#

Noetherian?

frozen merlin
#

yeah

alpine kindle
#

wait would these equations work nicely in any noetherian ring

frozen merlin
#

every ideal is finitely generated, so if wikipedia has served me well then you'd be able to write every "variety" as a finite union of irreducible "varieties" (or whatever you call them in a power series ring)

#

honestly I know 0 alggeo don't take anything from me

alpine kindle
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yeah

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there may be an issue of convergence tho

frozen merlin
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I wonder if you can make a ring of convergent power series by modding out divergent things

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wait no that's not an ideal

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nvm

honest veldt
fervent pebble
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ew

honest veldt
#

fellas for the backwards direction, do i literally just say that {p_n} is a subsequence of {p_n}

honest veldt
#

I just got "proof is left to the reader"'d

honest veldt
#

im going with it, thank you wewe

median zinc
# honest veldt

I'm not an analyst but you could try contradiction to be more clear

honest veldt
#

or are you talking about the forward direction

median zinc
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no the backward

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if there exists a single subsequence that does not converge to p

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anyway I'm not an analyst

honest veldt
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that contradiction hypothesis is for the forward direction tho

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if i were to use contradiction for the backward, it'd be assuming that {p_n} doesnt converge to p

median zinc
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no

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Forward is
p_{n} converges to p -> every subsequence of p_n converges to p
Backward is
every subsequence of p_n converges to p -> p_{n} converges to p

honest veldt
#

okay, great

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so the contradiction hypothesis for the backward would be....?

median zinc
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assume for contradiction = assume there exists one (or more) subsequence of p_n that does not converge to p

honest veldt
#

i think you're confused about something here, that hypothesis works for the forward direction, not the backward

median zinc
swift sinew
sleek wing
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yeah that's proof by contrapositive

honest veldt
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To prove a statement "If A then B" by contradiction, you say "Suppose A and not B"

swift sinew
median zinc
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Oh yeah

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You're right

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assume there exists one (or more) subsequence of p_n that does not converge to p and p_n itself converges to p

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Right sorry

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That should get a contradiction

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And prove the backward direction

honest veldt
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Not quite still

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you're still doing the forward one

median zinc
swift sinew
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Pepper, try writing this as p iff q and identifying what p and q are and working with contrapositives and stuff so you know what you’re proving and assuming

proud quail
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correct contradiction for backwards implication: ||suppose every subsequence of {p_n} converges to p, and for a contradiction suppose {p_n} does not converge to p||

median zinc
#

I think this proof works?

honest veldt
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For the forward, I did it directly by saying that
For any $\epsilon > 0$, there exists an N such that $n \geq N$ implies $|p_n - p| < \epsilon$. So, for any subsequence ${p_{n_i}}$, $n_i$ is eventually $> N$ for all $i > j$, for some $j \in \mathbb{N}$. So $|p_{n_i} - p| < \epsilon$ for all $n_i$ with $i > j$

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this works?

fathom swallowBOT
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gusfringerpro2009

median zinc
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Seems ok to me

honest veldt
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Sweet, thank you

median zinc
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But I'm really bad lol

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X_X

honest veldt
#

No worries, it happens lol

median zinc
#

Analysis is my bane devastation

honest veldt
#

isn't it everyone's devastation

limber thunder
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no, git gud

ripe wasp
#

how is hatcher’s notes on point set topology compared to a standard text like munkres or mendelson?

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it seems very short and concise

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so i thought i could prob go through it in a few weeks then do analysis from apostol

limber thunder
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particularly all you should need to learn alg top from his text

limber thunder
ripe wasp
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because i want a good foundation yk

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after i finish linear algebra from ladw, i'm probably gonna be on summer vacation so i'm gonna really grind out some math during that time

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hopefully i can make significant progress on apostol during that time

primal seal
#

I think you’re on a different planet

ripe wasp
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idk how much im gonna get done though

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i registered for aops's group theory course

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seems like a baby first course in abstract algebra

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i flipped through the big ass textbook they sent me and it looks pretty cool

dire mulch
#

Hmm, I am under the impression lee's smooth manifold requires a decent understand of analysis.

primal seal
#

This kid is out of his mind

ripe wasp
primal seal
#

We believe you brother

ripe wasp
# primal seal We believe you brother

idk man, i just like planning into the future this is all subject to change, i'm probably gonna take twice as long to do all of this than im planning due to burnout and school tbh

primal seal
#

I think you should regard fairly sophisticated math texts with more respect than the expectation of finishing them in the same time as Harry Potter

leaden torrent
fair mural
toxic schooner
#

this is common here

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much to my sadness

primal seal
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😔

toxic schooner
#

tfw 9th graders want to do diff geo

primal seal
#

They THINK they want to

toxic schooner
neat lintel
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If u do it fast. Chances are that u might understand a concept wrongly

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And have to spend more time on it

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I did this very mistake

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Tried calc 1 in grade 8th

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I could do sums. Completed calc 1 in 7 months. Proceeded to calc 2. Integration killed me

ripe wasp
# primal seal I think you should regard fairly sophisticated math texts with more respect than...

i'm not trying to read it like harry potter, i'm just saying i just wanna go through those texts, ofc i will be doing as many exercises i think are necessary and doing most of the proofs left to the reader. sorry if it came off like i was gonna breeze through all of this, that wasn't my intent, i just like to have a solid plan i can follow as i like scheduling and i feel more secure when i know what i'm going to next and in the future. as for my age, i'm not sure why thats relevant, perhaps you think i'm not ready for studying higher level math and thats understandable, but thats what learning is for isn't it? if i'm not ready, i'll probably realize that when i'm actually going through the material and then i can act on that then by reading through some other easier text to fulfill the prerequisites. its better to try and fail compared to not trying at all, as im sure you know.

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i'm just genuinely interested in these topics, im not trying to come off as a know it all or something, sorry if it seemed that way

ripe wasp
neat lintel
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Luckily I am doing from stewarts

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An excellent book

ripe wasp
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yeah i have stewart as well, i sometimes use it for practice problems and such

primal seal
#

I’m over it bro, and there’s no beef. I’m just letting you know you sound like you’re planning your lunch on the 4th of July today. Fairly unbelievable circumstances I’d say. Best of luck, talk soon 🙏

toxic schooner
ripe wasp
sterile hare
primal seal
#

And that’s all folks

primal seal
#

I knew it; my spidey senses were going off… through the Internet! At least it’s confirmed

toxic schooner
primal seal
#

@velvet dagger case in point above

bright hill
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good luck sean, I believe in you!

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@light needle where are your typed solutions to rudin?

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I couldn't find them in your website

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also, is this a bug or do you only have 2 posts in your blog?

feral salmon
light needle
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yeah i havent updated my website in months rip

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i can send em to u if u like tho lol

dense belfry
#

John you have a website?

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Lmao

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I have never looked at your bio

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Well that's not true

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But I've never parsed the fact that you have a website there

light needle
#

lol

bright hill
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that'd be awesome

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I like the minimalistic style btw opencry

light needle
#

lol devastation

dense sorrel
light needle
#

yeah for now

dense sorrel
#

I havent seen any sophomore reading atiyah mcdonald

light needle
#

atiyah mcdonald bleak

dense sorrel
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wait your even reading hartshorne lol

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I admire you

light needle
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no i went with other sources

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hartshorne bad

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i learnt AG out of garthmanns notes

dense sorrel
#

you mean this?

light needle
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yeah these are like p well written and honestly p light to read

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unlike hartshorne which will make u want death

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i didnt finish it btw, only until ch 7 or so

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gonna resume the rest in the summer

dense sorrel
#

hmm

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aren't class notes concise tho

light needle
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they are but honestly just give ch1 a read u will see what i mean by light read

dense sorrel
#

i don't have necessary prerequisites but i'll give it a try

light needle
#

oh yeah just blackbox the commutative alg probs

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he kinda does that

dense sorrel
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oh okay

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Lang's "algebra". Good reference, I learnt Galois theory out of it and it was pretty nice.

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btw how did you even do this

neat lintel
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HELPERS anyone alive

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I NEED HELP

long matrix
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AND the channel descriptions.

neat lintel
#

We all do starebleak

vagrant moss
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So what is tangent, like not what it's used for in triangles, I mean it's actually meaning

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I think it's something to do with circles

long matrix
#

googlable

vagrant moss
#

Ok 🤷‍♂️

neat lintel
long matrix
#

neither is your pretty specific definition

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that does not seem to apply to the context they need

neat lintel
#

I think otherwise

long matrix
#

I think what I said is plenty helpful

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You should try to look up your questions first before asking.

neat lintel
#

What? Lol

vagrant moss
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I saw an hour long video

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And that's a long video

long matrix
#

it makes no sense.

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in the context of euclidean geometry

vagrant moss
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Yeah but how do I get tan from that

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Or cos or sin

long matrix
#

Yeah you should probably look up your question

vagrant moss
#

Well what do I search?

long matrix
#

In the first place you weren't clear which 'tangent'

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you were after

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It's used to mean different things

vagrant moss
#

Didn't know there were others 🤷‍♂️

long matrix
#

???

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Cmon...

fiery coral
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Im so black

neat lintel
vagrant moss
#

I'm 15 what do you want from me 😔

long matrix
long matrix
#

if you don't... then time to acquire it

neat lintel
#

If you're so knowledgeable then how about you say that in the first place instead of directing people to google things

long matrix
#

If there's something you don't get from what you look up, then by all means ask

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but asking with 0 effort put in isn't the way

long matrix
vagrant moss
#

Just wanted to talk in this server mostly 😔

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But whatever

neat lintel
#

It wasn't wrong

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And you agreed with me just now by saying it was inaccurate

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You just contradicted yourself

long matrix
#

What?

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??????

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Inaccurate is synonymous with incorrect/wrong

neat lintel
#

No

long matrix
#

sorry?

vagrant moss
#

why is tan(1) positive then tan(2) negative?

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Like where is the pattern?

stark birch
#

Look at the definition of tan(x)

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In particular, that tan(x) = sin(x)/cos(x)

long matrix
#

indeed, you want the trigonometric tangent it seems

vagrant moss
#

Yes

stark birch
frozen merlin
#

it repeats this pattern

vagrant moss
#

Oh ok so then where did the pi/2 come from?

frozen merlin
#

so in particular since 0 < 1 < pi/2 < 2 < pi, you will get tan(1) positive but tan(2) negative

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wait are you doing trig in radians or degrees

long matrix
#

I think they have no idea what tan is.........

vagrant moss
#

Either 🤷‍♂️

long matrix
#

Look it up srsly =...=

fair mural
vagrant moss
frozen merlin
#

there's an asymptote at pi/2 because tan(x)=sin(x)/cos(x), and cos(pi/2) = 0

fair mural
#

you can’t just say “either”

long matrix
#

now I have no idea what you mean...

vagrant moss
fair mural
#

you just have to learn trigonometry

fervent pebble
#

^

long matrix
#

You are asking the wrong questions ngl

vagrant moss
#

Oh ok

long matrix
#

There's no point asking why, what, where

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without even first understanding what the thing is!

vagrant moss
fervent pebble
#

"where can i learn more trig"

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the answer is khanacademy

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here i'll link

deep mango
#

Gelfand's trigonometry book smugsmug

fervent pebble
stark birch
vagrant moss
#

XD thank you

fervent pebble
#

whenever i see gelfand i think of the chess player 💀

deep mango
#

Israel Gelfand is one of the best mathematicians of all time

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Just look at this shit

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and somehow even though he's so accomplished and smart, his books for high school math are also really good!

fervent pebble
#

huh

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that's actually pretty sick

light needle
#

Gelfand transforms make me coom

deep mango
#

like usually it doesn't work that way

frozen merlin
#

also lasker of the lasker-noether theorem is the same guy who was world chess champion for 27 years

deep mango
#

Wow

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That's cool

fervent pebble
#

ooh i knew that much

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lasker was dominant

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except kindaaaaa disputed?

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a little?

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his brother has one of the most famous king walk games of all time

neat lintel
#

Very well hidden lol 😂

long matrix
#

@ mniip, rename it to locked to stop these fools from complaining

cold needle
#

i think its funny that its hidden but not really hidden at all

modern geyser
#

it is indeed not hidden

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because everyone can see it

ripe wasp
#

i always wondered

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why r those channels hidden

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is it bc it would clutter up the available math help channel too much if they were all there

limber thunder
#

yeah you don't want 42 help channels at all times

ripe wasp
#

yeah good point

rich grove
#

the current system is shockingly well designed

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I'm used to much more inefficiency in big servers

charred mortar
#

yeah it's pretty efficient here

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occasionally you have the weirdos who somehow don't see the clearly visible help channels and ask their questions here, but for the most part it's good

fervent pebble
#

occasionally?

limber thunder
#

occasionally

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I wish

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weirdos, more like pampered children who just want people to answer their HW or w/e

charred mortar
#

yeah fair

silk flower
#

Chemistry has math right?

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so can I send help here for our chemistry assignment?

ripe wasp
#

i mean just because one part of chemistry has math doesn't imply ur chem hw is gonna have math

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but if it is the math part you need help with, sure

long matrix
#

then i dont have to see anything here

flint canyon
#

So yea

cyan goblet
#

can someone explain an eigenstate to me as if i were five

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the definitions online just arent clicking

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as if i were five with understanding of basic quantum mechanics*

static loom
#

do you know what an eigenvalue and eigenvector are?

rocky shuttle
static loom
#

I agree but I'm not gonna waste time reexplaining something they already know for the sake of a fantasy

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trying to gauge what this person really knows first lol

cyan goblet
#

i get that eigenvectors are referred to as eigenstates in quantum mechanics, i just can't draw the connection

static loom
#

eigenvalues are the results you can get from doing an experiment and those correspond to your distinct observable states, those are your eigenstates

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generically speaking your state is a superposition of these which is basically your probability distribution for how to get the outcome of doing your experiment

cyan goblet
#

oh i see

static loom
#

it probably helps to focus on the double slit experiment

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remember, these operators are hermitian so they have all real eigenvalues and distinct eigenvalues correspond to orthogonal eigenvectors (well, eigenspaces)

cyan goblet
#

mhm

static loom
#

when you make a measurement, you're doing a projection, that's the "collapse of the wavefunction"

cyan goblet
#

i dont think ive learned about wavefunction yet but continue

static loom
#

no

cyan goblet
#

i know the collapse part

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oh

static loom
#

like I'd rather not just ramble

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but I'll have dialogue with you

cyan goblet
#

mkay

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so ik that observing an observable collapses it into a state right?

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like measuring spin up/down on z axis of a particle will collapse the particle into either spin up or spin down

static loom
#

sure

cyan goblet
#

is eigenstate then just a measured state of a particle?

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like if we measured spin up, then that is its eigenstate?

static loom
#

think of eigen-anything as being relative to a specific operator

cyan goblet
#

mkay

static loom
#

so like if you're measuring up/down you have its corresponding eigenstates because the operator simply scales by the eigenvalue

cyan goblet
#

mhm

static loom
#

but up is a superposition of left and right, which are not eigenstates of that operator

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but they are eigenstates of their own corresponding operator

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it's really just linear algebra, eigenstate is just an eigenvector of a linear operator

cyan goblet
#

so like up would be the eigenstate of an operator on up/down?

static loom
#

yeah

cyan goblet
#

ohhhh okay

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tyvm

static loom
#

then it's a kind of important thing to look for, what operators can be simultaneously diagonalized in a basis

cyan goblet
#

i just got to simultaneous diag/triangulization in h+k lol

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idk if spelled that right

static loom
#

like when you're looking at certain properties you will find that certain states in one basis are a superposition of multiple states in another basis

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like how up is a linear combination of left and right or position is a fourier transform of momentum stuff like this, you can't ever cleanly measure both exactly because one is literally made up of multiples of the other

cyan goblet
#

ohh i see

static loom
#

so for two things like this, that trickles through in looking at their standard deviations as being bounded below by the expectation of a multiple of the expectation value of their commutator

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that's your heisenberg uncertainty principle

cyan goblet
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aha

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learned about the uncertainty principle but never drew that connection ig

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makes sense now

static loom
#

well it makes (a little) more sense when you derive it yourself directly from the representation

timid spindle
#

there is is thing called critical state

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after which a material fails

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it turns out critical state surface is a tensor

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it's looks kinda cool

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if you plot

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it

bright hill
#

bertrand russel is cool

dense sorrel
#

actually his book on philosophy is good too

bright hill
#

what do you guys think of proofs such as these?

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I feel like I don't learn much other than proof reading

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they look elegant and simple

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and they do make sense

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but the arguments seem like they were knit out of thin air

primal seal
#

🙄

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That’s Rudin

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How are you at all surprised

dire mulch
#

I guess you should ask question. why does he use the conjugate of b_j instead of using b_j. When do we have lhs is equal to rhs.

dire mulch
#

But you can just move on.

bright hill
#

do you think attempting to prove the theorem beforehand is helpful?

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and should I spend too much time on that?

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"only" devastation

dire mulch
bright hill
primal seal
#

@bright hill what is your background and experience?

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What are your goals through reading the book?

bright hill
#

for the memes?

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obviously

dire mulch
#

Doing rudin because I like analysis. Also the way he does stuff makes it fun. I am not a side character when reading rudin.

bright hill
#

but seriously tho, I wanted to know what rudin was like and see what everyone is talking about

dire mulch
#

Pencil and paper, writing stuff down. Trying to figure out what he is saying. Using other resources.

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That is fun for me.

brave hollow
#

random question plegasus, irrelevant to this conversation but

primal seal
#

@dire mulch certainly; the way it was intended to be done

brave hollow
#

are you into masochism by any chance?

dire mulch
#

lol I don't think so.

brave hollow
#

well I am :)

bright hill
#

well, I certainly am

brave hollow
#

you can use this info however you like

primal seal
bright hill
primal seal
#

At least in terms of “maturity” requirements

dire mulch
#

Also I did a few chapters of abbot understanding analysis before starting. So I already have the so called maturity.

bright hill
#

a few chapters of hubberd

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I'm just starting to seriously learn maths

primal seal
#

Ah ok; it might help to try a different analysis book- they’ll have the same info but others can be better at explaining things

charred mortar
#

I’d probably end up using another analysis book for exposition and coming back to Rudin for some of the exercises tbh

primal seal
#

And having friendlier exercises

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Lol

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Confirmed

brave hollow
#

if you are not starting analysis with papa rudin are you even doing analysis?

bright hill
#

that seems like good advice

primal seal
#

But if you want an answer to your question

dire mulch
#

papa rudin hmmCat .

primal seal
#

If you get stuck on a proof usually 2-3 days of thinking about it is decent

bright hill
#

you mean diy style or just reading the proof?

primal seal
#

Read the theorem and try the proof without looking

dire mulch
#

DarQ try using other references if you want to stick with rudin.

primal seal
#

Give yourself 2-3 days before asking for help

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Then get s hint

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2-3 more days

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Etc..

bright hill
#

he was 28 tho

brave hollow
#

maybe you can say he duked it out during his thesis defense

bright hill
bright hill
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but I'm just doing rudin on a whim so I'll go back to calc 3 after finishing like,

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point set

dire mulch
#

lol I haven't done calc 3 yet.

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Still stuck doing analysis and linear algebra.

bright hill
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cool

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hubberd is really good if you want to do calc 3 and lin alg at the same time

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that's what I'm doing

dire mulch
#

Probably going to calc on manifold by spivak.

bright hill
#

it covers a lot KEK

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more than 3 courses, someone told me

primal seal
#

These guys are just talking

brave hollow
#

lucy is your pfp a popular math/physics youtuber?

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idk she reminded me of some1 on youtube

bright hill
#

I thought it was you opencry

bright hill
#

lmaoooo

toxic schooner
brave hollow
#

it would be weird if some1 had a gif file of themselves saved as their pfp

toxic schooner
#

chrew

brave hollow
#

physics girl

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I think

dire mulch
#

The content looks nice.

bright hill
brave hollow
bright hill
#

wut

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hubberd has 800 pages lmfao

toxic schooner
toxic schooner
bright hill
#

nah, the first chapter is pretty easy tbh

dire mulch
#

Yep.

bright hill
#

haven't seen the exercises yet tho NervousSweat

dire mulch
#

I was more excited to get to chapter 2, so I only did half of the exercises in chapter 1.

fair mural
#

doing half the exercises of a chapter is good though

grand axle
#

What should I learn first: advanced calculus or advanced chemistry, or should i learn both at the same time

dire mulch
#

Lol is that a typo.

#

advanced chemistry?

grand axle
#

What part of it do you think is a typo

dire mulch
#

nvm.

grand axle
#

But I guess advanced is the wrong word, I'm just thinking stuff like electrochem and thermochem to get ahead

dire mulch
#

I meant it more like I thought it was typo comparing those two subjects.

grand axle
#

Ahhh

#

What you are saying is that they are different in terms of difficulty?

dire mulch
#

No, nvm. I was mistaken.

grand axle
#

Ah, no worries

dire mulch
#

If you can manage both do both. But I would will pick advanced calculus.

#

Since I don’t like chemistry.

grand axle
#

Makes sense

toxic schooner
grand axle
#

I've already started taking notes on advanced calc

fair mural
toxic schooner
dire mulch
#

Leave us alone.

primal seal
grand axle
primal seal
#

Yeah then if you’re just building up start learning both

grand axle
#

I'm not even sure how I am defining advanced calculus

dire mulch
#

Advanced calculus all I think about is spivak calculus.

fair mural
#

do you just mean analysis

grand axle
#

I probably better start with basic calculus

primal seal
#

Some calc shows up early on in things like higher-order rate laws; but you don’t really need to understand it formally, just computationally

#

Yeah basic calc and basic Chem work well together

grand axle
#

I don't know a lot of calculus, and my knowledge is spread throughout.

dire mulch
#

That is normal if you haven’t study/taken calculus yet.

primal seal
#

It’s mostly differential calculus early on

#

Reaction Kinetics/rate laws

grand axle
#

Yeah I don't know why I said advanced calculus 😂

random bronze
#

What

primal seal
#

Some diff Eq maybe for radioactive decay and such

grand axle
random bronze
#

what is advanced calculus

dire mulch
#

Something like spivak calculus.

grand axle
#

[A] = -kt + [A]o -> ln[A] = -kt + ln[A]o -> 1/[A] = kt + 1/[A]o

primal seal
#

Looks right

#

About to get in the car though so can’t confirm

grand axle
#

No problem

#

I looked it up

primal seal
#

Cool ok

random bronze
#

Interesting

grand axle
#

latural nog

fathom swallowBOT
#

The current time for DarQ is 09:06 PM (CEST) on Fri, 08/04/2022.

vocal jewel
#

,ti

fathom swallowBOT
#

You haven't set your timezone! Set it using the interactive timezone picker with ,ti --set.

vocal jewel
#

,ti --set

fathom swallowBOT
#

Your timezone has been set to Europe/Paris!
Your current time is 09:15 PM (CEST) on Fri, 08/04/2022.

vocal jewel
#

,ti

fathom swallowBOT
#

The current time for ................................ is 09:15 PM (CEST) on Fri, 08/04/2022.

random bronze
#

,ti

fathom swallowBOT
#

You haven't set your timezone! Set it using the interactive timezone picker with ,ti --set.

random bronze
#

,ti --set

fathom swallowBOT
#

Your timezone has been set to America/Detroit!
Your current time is 05:05 PM (EDT) on Fri, 08/04/2022.

random bronze
#

,ti

fathom swallowBOT
#

The current time for Clive is 05:06 PM (EDT) on Fri, 08/04/2022.

swift sinew
#

@vocal jewel @random bronze
In the future, this stuff is better suited for #bots or #latex-testing

mild echo
#

hey guys, not sure if the news was broken here (I did a few searches but nothing came up) but I'll put it up anyways.

Michael David Spivak was born May 25, 1940, in Queens, New York.
He died October 1, 2020, in Houston, Texas.
He suffered a broken hip earlier in the fall, and had been confined to an extended care facility following that mishap.
—Obituary in TUGboat Vol 42 by Barbara Beeton (https://www.tug.org/TUGboat/tb42-3/tb132beeton-spivak.pdf)
(emphasis added by me)

Information about his death was very slow to reach most of his colleagues and collaborators (afaik, the news only broke around October 2021, a year after his death), so I just wanted to put it out there. There were previously rumours of his demise and so on, but this is just to give some closure to anyone who may have been concerned.

#

since there is a lot of discussion about his books etc, I thought it may have been appropriate to just let people know.

Most of his books are available via the Hindustan Publishing Corporation, although many other texts by the Publish-or-Perish Press aren't at the moment.

#

ah, I just found a discussion talking about the first edit on Wikipedia; it was unfortunately correct, but now there is a proper source in his obituary linked above.

fervent pebble
#

yeah, i actually learned he was dead yesterday :(

#

tragedy

#

well

#

he'll live on forever in his writing

limber thunder
#

is he really

#

I've seen it come up in searches but nothing confirms nor denies the claim

fervent pebble
#

yeah, spivak's dead

#

it's on his wiki

#

Michael David Spivak (25 May 1940 – 1 October 2020) was an American mathematician specializing in differential geometry, an expositor of mathematics, and the founder of Publish-or-Perish Press. Spivak was the author of the five-volume A Comprehensive Introduction to Differential Geometry.

fair mural
#

i’m sorry but

bronze pelican
tender tulip
#

Let’s say you have a complex Laurent series with a radius of convergence R, could you determine it’s behavior on the boundary by substituting z for Re^it

vivid halo
#

perhaps, but note that the behavior on the boundary can be pretty bad

#

for instance you can have power series with radius of convergence 1 that converge nowhere on the boundary, or converge at exactly 1 point on the boundary

tender tulip
#

I know

vivid halo
#

yeah just saying that you probably need more than just doing a basic variable substitution to check the behavior

#

like you can do this substitution, then what?

#

how can you use this to see e.g. that every convergence set has to be F_\sigma\delta

tender tulip
#

for n natural

chilly hull
mint patio
#

Are moments "linear"? Idk if that's the right word

#

I think it is

#

Say you have a random variable X = A + B + C + ...

#

Then the pdf of X will be the sum of pdfs of A, B, C, ...

sturdy bluff
#

anything linear is basically proportional

mint patio
#

And E[X^n] = int x^n * f_X(x), where f_X(x) is the pdf for X

sturdy bluff
#

x go up y go up

#

etc

mint patio
#

Then just decompose f_X(x) as f_A(x) + f_B(x) + f_C(x) ... and distribute the x^n and then split the integrals up (linearity) and convert those into expected values

lone carbon
#

just wanted to share that

mint patio
fervent pebble
#

lmfao

limber thunder
static loom
#

obviously you can't use the standard calculus trick of f'(x)=0 and solve for x because it's not differentiable

lone carbon
#

ooh that is a good one. I can see visually it's 4/3 but it's not clear why

#

just playing around in Desmos it seems the trick is to add terms two at a time instead of one at a time to get those flat intervals where it's at the maximum

#

and then you get 1 + 1/4 +1/16 + etc

#

the solution you gave is obv a lot cleaner 😅

wind abyss
#

ooh mero that’s beautiful

dense ledge
#

do you guys know a software for digital writing? I'll use my drawing tab to do math scratches. Any suggestions?

#

With smoothing feature please

stark birch
#

OneNote is common enough.

Could also literally just use MS Paint, that's more my vibe. I also used Microsoft Whiteboard a few semesters back for teaching a class (I forget why, I think MS Paint wasn't playing nice with my art tablet?)

dense ledge
#

I want it with a photoshop smoothing brush effect

stark birch
#

Oh I missed the bit about smoothing. My bad. draconDerp

dense ledge
toxic schooner
bronze pelican
#

Mspaint is for when I need to make quick notes

#

That don't need to be saved

#

OneNote is for more formal online presentations, things i need to prepare in advance

toxic schooner
#

i hate ms products

#

they never work nicely for me

dense ledge
toxic schooner
#

it has some extent of it ig?

#

it smooths out lines and stuff

#

not sure about handwriting

dense ledge
#

yea it has a bit. It's actually better than MS. I'll still look for better. Thanks for the reco.

frozen merlin
devout nacelle
#

I'm not sure about smoothing features but it's good enough for my usage

delicate knoll
#

Guys, how would you write good morning using math expressions where mathy people would understand?

#

Silly,but I drink to much coffee to by the way

vast surge
#

$\mathfrak{good}\text{ }\mathfrak{morning}$

fathom swallowBOT
#

Zorn's Lemon

delicate knoll
#

I think the nable gradient would a start

delicate knoll
#

It strange explaim this

#

Analogous

#

I would use gradient for first step
$\nabla$

fathom swallowBOT
#

THCampbell

delicate knoll
#

Humm

delicate knoll
ripe wasp
#

$\mathbb{G} \mathbb{O} \mathbb{O} \mathbb{D} \ \mathbb{M} \mathbb{O} \mathbb{R} \mathbb{N} \mathbb{I} \mathbb{N} \mathbb{G}$

fathom swallowBOT
vast surge
delicate knoll
#

i working that out by using nabla

#

i know it silly, but c´mon let man dream a bit with possibility

#

and to impress a girl

vast surge
#

Let $S={\text{mornings}}$. Theorem: For all $x\in S$, $x$ is good.

fathom swallowBOT
#

Zorn's Lemon

ripe wasp
#

u could use like quantifiers to make it look more math-y ig

delicate knoll
vast surge
#

I do not.

toxic schooner
#

zorn here only knows maths

#

feelings and "knowing what i mean" are things beyond them

vast surge
#

And I'm not even good at maths!

cyan goblet
#

,w ContourPlot3D[(x^2 + 9/4 y^2 + z^2 - 1)^3 - x^2 z^3 - 9/(200) y^2 z^3 == 0, {x, -2, 2}, {y, -2, 2}, {z, -2, 2}]

fathom swallowBOT
cyan goblet
vast surge
cyan goblet
#

LMFAOO

vast surge
#

Or, if you guys have done complex anal, you could ask her to leave a residue around your pole.

#

(sorry, I was being gross there)

cyan goblet
#

i gotta write these down

hushed turret
#

that's a pretty good one

ripe wasp
#

thats actually a good one

toxic schooner
#

i dont get it

#

😭

vast surge
#

I'm not explaining the part of it that's dirty to you, but it was a pun on Cauchy's residue theorem

toxic schooner
#

explain the dirty part

#

😭

vast surge
#

butt sex

ripe wasp
#

you could also say something about the hairy ball theorem 😏

toxic schooner
#

how is residue theorem related to butt sex thonk

mild echo
#

so sadly no more parts to the Physics for Mathematicians series.

vast surge
toxic schooner
#

im 18 what are u saying

vast surge
#

I'll explain it to you when you're older

toxic schooner
#

fine whatever

vast surge
#

After you've taken complex analysis

toxic schooner
#

goddamn it

#

that will be like

#

at least a year from now

#

not fair 😭

delicate knoll
vast surge
vast surge
delicate knoll
delicate knoll
vast surge
# delicate knoll oh you mean, me and her doing maths togerther?

I mean, honestly, yeah. It's less tacky, you guys both like math, and it'll give you time to get to know her better to see if you actually like her as a person or if you're just infatuated. If you get to a point where you're comfortable, also feel free to just point-blank ask her out. No cheesy lines or anything; just actually ask her.

#

Unless I'm misunderstanding you; you did only say that you want to impress her, not that your interest was romantic.

supple totem
#

Hi. I am planning to move to Canada. If there are people here who are also interested, please write to me. I am looking for people who are planning to immigrate to Canada)

vast surge
supple totem
#

._.

delicate knoll
delicate knoll
delicate knoll
#

you are nice Guy

odd narwhal
#

I won't elaborate further

fair mural
#

that joke is actually disgusting devastation

sleek wing
#

LOL

delicate knoll
vast surge
cold needle
#

no more pls

limber thunder
stray kite
#

some guy in the wiki talk page said so lol [i know very good source][

sick burrow
#

Where can I find the ceo of geometry

#

I just wanna talk

odd narwhal
#

Which one

rocky shuttle
#

Euclidean geometry?

sick burrow
#

Euclidean geometry especially

rocky shuttle
#

He died

sick burrow
#

But really the ceo of all forms of geometry

#

Actually algebraic geometry seems kinda cool though I don't know any

#

Diffgeo can go to hell though

fervent pebble
#

im the ceo

#

wdyw

sick burrow
#

🗡️ hypersully

fervent pebble
#

hmmmm

#

you want a knife?

#

nah

#

ryc typing 👀

rocky shuttle
#

Someone's picking a fight with geometers

deep mango
fervent pebble
#

ryc is a penguin?

deep mango
#

No

#

Brofibration

sick burrow
#

You're holding the knife wrong

#

🐧 🔪

deep mango
#

Oh yeah they should be switched

sick burrow
#

Is what you want

deep mango
#

Thanks

#

I'm not holding the sword though

#

Also I don't like geometry

#

Well I do but I have geometry hw to do rn which I don't want to do

sick burrow
#

Holy shit based ryc

deep mango
#

I have to compute the coefficients of the riemann curvature tensor in arbitrary coordinates

rocky shuttle
#

Why not do it coordinate-free

sick burrow
#

I despite any computations involving trig functions

deep mango
#

It's fine

deep mango
#

I much prefer how we learned it to how I learned it in undergrad

#

Which was "here's the definition in coordinates, somehow by some magic it corresponds to holonomy of parallel transport"

rocky shuttle
#

Yeah, I also hated Christoffel symbols before doing it coordinate-free

delicate knoll
narrow sedge
#

hi guys im new but i hope we will all get along ❤️

deep mango
#

Welcome!

tender tulip
#

Can I simply define the symmetric group as (set) automorphisms

#

because I’m proving it the order of S_n is n! through the stabilizer of every element having cardinality (n-1), and proceeding with flat out saying that the cardinality of the orbit is the cardinality of S_(n-1) by def, of which the orbit is “set isomorphic” to S_n/stab(x), so you can use Lagrange’s theorem

deep mango
#

But careful to specify set

tender tulip
#

Just use a different variable for the group troll

torn willow
#

I think I have a new perspective on induction.(or maybe this is really really obvious)
So you start with a base set satisfying property X. The induction step involves adding more elements to the set using the fact that elements of the base set have X.

You can say X holds for all elements in some set A,if there exists a non empty base set with X and given any element a in A,you can eventually get it in X in a finite number of steps

#

Well,This is a bit more nuanced than that

#

And is not limited to natural numbers

#

According to this perspective strong and weak induction are clearly the same thing

sick burrow
torn willow
#

I have no idea

#

Maybe this is the regular perspective?

swift sinew
sick burrow
#

The chad perspective on induction is deriving a contradiction from a minimal element not satisfying the property

#

Because then you can induct on the ordinals

torn willow
#

That is generalisable to more than just N right?

#

I am looking for a definition of induction that's as "general" as possible

sick burrow
#

Yeah that's how you do transfinite induction

sick burrow
#

I feel like transfinite induction is better/more general

torn willow
#

Doesn't Peano Structure always reduce to something bijective to N

swift sinew
sick burrow
#

Peano structure is unique

#

isn't this just... trivially false?

#

by Lowenheim-Skolem

#

seriously though what the fuck is this

#

I'm trying to read their "proof" to find the issue but the notation is so bad it's difficult

acoustic surge
#

0' bleak

sick burrow
#

that's not even that bad

#

certainly isn't the worst part

#

so it seems they just casually assume that P is N?

swift sinew
#

Maybe the induction principle regarding wffs is what he’s looking for

sick burrow
#

wffs?

sick burrow
#

wait so how is that related to the "uniqueness" of Peano structures?

swift sinew
#

I wasn’t intending for it to be. I was referring to Bye’s inquiry into the most general form of induction

sick burrow
#

I'm not sure how much I trust proofwiki now given that they stated and "proved" a "theorem" that's verifiably false

fervent pebble
#

proofwiki is dumb as fuck

#

gods some of the things there are idiotic

sick burrow
#

what else do they say monkey

swift sinew
# sick burrow

I’m still a bit confused on your claim that this is false

sick burrow
#

are you familiar with the Lowenhim-Skolem theorem?

swift sinew
#

Admittedly, no

sick burrow
#

it states that if a first order theory in a countable language has an infinite model then it has a model of all infinite cardinalities

#

so in particular, Peano Arithmetic has an uncountable model

#

how do you find a bijection between that and N

fervent pebble
#

with big brain sotrue

sick burrow
#

I mean it's a trick question because uncountable sets don't exist and all of modern mathematics is a lie

devout nacelle
#

Do Peano Axioms actually constitute a first order theory?

sick burrow
#

I think so

devout nacelle
#

Wikipedia says induction is second order

devout nacelle
fervent pebble
devout nacelle
#

I vaguely remembered Tao mentioning something along these lines in Analysis 1

fervent pebble
#

manan did u go to ucla

#

also were u a cali resident?

devout nacelle
devout nacelle
fervent pebble
#

was tao not always at ucla or smthn?

devout nacelle
#

Oh I was referring to his book, Analysis 1

#

Not any class with him haha

fervent pebble
#

ohhhhh

light needle
#

no manan signed up for his masterclass

devout nacelle
#

10/10 you can't call yourself a real mathematician if you don't pay for his masterclass

toxic schooner
#

so true..............

vast surge
#

Is his masterclass worth getting?

delicate knoll
delicate knoll
#

consider a open interval

#

what is next?

primal seal
#

Yeah Tao is here

#

Has one of the funniest faculty webpages that exist I think

#

Basically tells everyone who’s trying to see/meet/email him to F off

#

😂

#

It’s great

toxic schooner
#

where

hushed turret
#

he's not quite so abrasive about it

charred mortar
#

We’ll never know who’s really tao here

torn willow
#

It's clearly Terrence Tao

rocky shuttle
#

@ tao

toxic schooner
#

i am tao

neat frost
shadow glacier
#

What to do with a method which produces all the correct results for a certain example, but doesn't work when generalized.
Is the method correct?

toxic schooner
neat frost
#

Extreme example: Algorithms for addition work for addition but don’t work generally for all operations

#

Doesn’t mean the algorithm isn’t correct

#

It’s just meant for a specific case (addition)

shadow glacier
#

An algorithm that works for all cases that you care about, but not all?

neat frost
#

Again

#

It depends

#

Sometimes there won’t be a general algorithm

#

Obviously if there does exist a general algorithm, then in most cases it is preferable to one that works only under specific conditions

shadow glacier
#

The one that works only under specific conditions doesn't feel like the "true" or "correct" algorithm.

neat frost
shadow glacier
#

Hmm

lunar spear
#

Everyone who isn't from finland is missing out smh, we have ville to help us with math

swift sinew
#

I do miss how gamy the burgers were in Finland

loud iris
#

Villi

lunar spear
#

ville

neat lintel
#

he called it the last supper

#

he knew it was going to be his last

#

he planned it from the start

swift sinew
#

Haven't you already been muted once or twice? Why ping me with this stupid shit

fervent pebble
#

pogggg my parents are finally getting me tested for adhd

limber thunder
#

pog I guess

fair mural
fervent pebble
#

im gonna get adderall 😎

signal glacier
wind abyss
#

is it nice?

neat lintel
#

hey guys

#

are there any periodic functions aside of trigonometric ones?

surreal sapphire
#

constant functions sotrue

hushed turret
#

f(x) = x mod n

static loom
#

pick an interval [a,b]

#

now define any function on it

swift sinew
#

Differentiability wouldn’t affect the infinitude of this set

static loom
#

now repeat this left and right, done

#

another fun periodic function is f(x) = 1 if x is rational, 0 if x is irrational

hushed turret
#

o wait im dumb

fleet raptor
#

Series for integral x^-x what you think?

inner finch
#

beautiful

sleek wing
#

maths truly is beautiful

neat frost
fleet raptor
#

Yes

frozen merlin
neat frost
#

Wew when are you gonna change your name to "Penis Wall"?

sleek wing
#

shaking my head

neat frost
#

shaking my smh

brave hollow
#

nice pfp wew

#

where'd you get it

sleek wing
#

internet

brave hollow
#

I thought it was a selfie

fleet raptor
#

Just beautiful

sleek wing
#

yeah hahahahhahah

neat frost
#

Someone doxxed him, uploaded a selfie to the internet, wew found it and made it his pfp

fleet raptor
neat lintel
#

How stunning.

inner finch
#

among us

neat lintel
#

its a fact about f(x)=f(x+p) for all x there is a fixed p and we know that this doesnt hold for all irrational numbers

#

i put it badly and wrongly

#

but more like irrationals and rationals stay what they are upon rational addition

#

The fact that the function changes from 1 to 0 in no time is just wow

neat lintel
#

it isnt continuous so yeah

#

So it can't be differentiable?

static loom
#

not a chance, for a limit to converge all its subsequences must converge to the same thing, so you can pick your values to be purely rational or irrational to make the limit of the difference quotient to go two separate things

neat lintel
#

This begs the question

#

Are there more irrationals than rationals?

fair mural
#

yes

long matrix
#

'more' sully

#

the rationals are countable, the irrationals are not

fair mural
#

bigger infinites shuri opencry

long matrix
#

if thats some indication

fervent pebble
#

gods imagine believing in bigger infinities

neat lintel
#

They don't go in one direction

#

Or anything

fervent pebble
neat lintel
#

ok

fervent pebble
#

and also a proof of density in r of q

cyan goblet
#

ok i feel like i cannot wrap my head around what spin is

#

like ive watched youtube videos and stuff and i get that an electron isnt literally spinning

#

and spin is the "intrinsic angular momentum" but i have no clue how to interpret that

#

ive also read some sources that compare spin to magnetic moment?

#

so like would this be spin up on z axis?

#

shitty drawing courtesy of ms paint and my mouse

ancient flame
#

what the fuck am I looking at

cyan goblet
#

my attempt at an electron

ancient flame
#

that looks obscene

cyan goblet
#

yeah...

ancient flame
#

you committed a war crime

#

but yeah maybe ask on the physics discord lol idk

cyan goblet
#

blo once said that we have better physics majors than the physics server

ancient flame
#

oh damn

steep mountain
#

no.

leaden torrent
#

are you learning this from a book or from wikipedia articles

#

if youre learning it from a book, just look at the worked examples

#

or the exercises or w/e

cyan goblet
#

im reading McIntyre

leaden torrent
#

then yeah, stop trying to intuit it and just view it as a mathematical quality

cyan goblet
#

shit

#

man that sucks

#

ive been trying to visualize it

ancient flame
#

mathematical contraband

sonic ether
#

even andrew doesnt know what spin is

#

intuitively

cyan goblet
#

like that one physics youtuber?

neat lintel
#

u drew hairy balls

neat lintel