#serious-discussion

1 messages · Page 546 of 1

stark charm
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o

wild lantern
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Lol

vast surge
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This was for whoever asked about differential galois theory by the way

neat lintel
#

yes (and as an unrelated note), it turns out that if a polynomial's derivative is irreducible in a field then the polynomial must be separable in said field

wild lantern
#

Do you have a reference or source you like for reading about differential galois theory?

errant ridge
#

damn differential algebra is so cool I wanna learn it so bad, but I need prereqs first kekw

vast surge
neat lintel
#

there should be books too

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I'm too busy with all the other math I'm doing, differential galois theory seems cool though

neat lintel
#

Hello, I would need someone who knows how to calculate the probabilities of winning or losing according to a percentage of success (I don't know if you understood me)

maiden bear
bronze pelican
#

Who tf came up with this colorscheme for a textbook cover

cyan goblet
#

my beloved yellow books…

fair mural
empty stratus
neat lintel
#

literal death

austere timber
#

;

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;

wooden flax
#

differential galois theory is also very cool

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i read a paper on it once

vast surge
primal seal
#

Reading it currently

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Although that may be a bootleg color scheme

bronze pelican
#

I referenced it for exceptional aut of S_6

sleek wing
fair estuary
#

Guys, there's a math fight in help room 2. What do I do?

open aspen
#

bring snacks

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start a betting pool

deep mango
fair estuary
#

Ok

deep mango
#

Ok this is not a fight

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nevermind

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Lol

fair estuary
#

They're fighting though

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About math

open aspen
#

(dont bring snacks to actual fights)

#

that is generally considered bad taste

deep mango
#

Yeah you only need to ping mods if it's like, vitriolic. An argument is fine

deep mango
fair estuary
#

Is there a way to separate them into teams and then they can collaborate on their argument?

deep mango
#

Lol

fair estuary
#

It's too messy rn

deep mango
#

They will have to self-organize

open aspen
#

form unions

cyan goblet
#

better not be forming unions in my beautiful us of a

fair estuary
#

^Jeff Bezos

broken compass
#

Hello! I'm not sure if this is the right channel for this, but I was wondering, do you guys think finding the surface area of a bean might be a good Math Internal assessment HL topic? I took inspiration from looking for the surface area of an egg and thought it would be similar in difficulty, and thus, good for a Math IA topic for next year, I'd really appreciate any perspectives on this🙏

open aspen
#

I think so! You can attempt to generalize methods to other irregular surfaces as well if it turns out to be too simole

#

And this will give you some personal motivation points or however it's called

azure nymph
#

The yellow books look so good

open aspen
#

anyone else enjoy just scrolling through latex documentation trying to guess at what the crazy notations could represent

fair mural
#

i just wow at the cool symbols

ancient flame
#

lol

azure nymph
#

These are like unreadable

untold sapphire
#

dope

limber perch
#

my type of textbook

torn willow
#

So,How does a normal PDE textbook look like?

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Random equation -followed by just lines and lines of derivation?

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Like this for example

stark charm
#

pretty much

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context and history for random equations

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and then the rest

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honestly its pretty aesthetic

static loom
#

that textbook cover is actually genius, it forces you to open it so that you don't have to look at it, thereby encouraging you to study more

leaden skiff
#

@nocturne tusk so do u wanna learn abt induction?

nocturne tusk
#

idk what I wanna learn icl

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I just wanna learn

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something

errant merlin
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induction is a must-learn

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very useful

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and also intuitive

nocturne tusk
#

I suppose so

leaden skiff
nocturne tusk
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sorry im having a big adhd moment rn

leaden skiff
#

if there is something specific you want help with let us know

errant merlin
#

You were originally trying to prove the power rule right?

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And someone recommended induction

nocturne tusk
#

yes

leaden skiff
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do you know the binomial theorem?

nocturne tusk
#

I know the basic stuff I think

leaden skiff
#

like, do u know how to expand $(a+b)^n$

nocturne tusk
#

like (3+x^-1)^7 or smth

fathom swallowBOT
nocturne tusk
#

I think so

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yeah yeah

leaden skiff
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do you want someone to help you prove it yourself or do you just want to see a proof of it?

nocturne tusk
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proof for myself i think

leaden skiff
nocturne tusk
#

idk the official notation but I cam get something

leaden skiff
#

yeah use whatever notation you want

nocturne tusk
#

$a^n+a^{n-1}\binom{n}{1}(b^1)+\cdots +a^0\binom{n}{n}(b^n)$

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awful latex but I think its semi readable

errant merlin
#

Nice, that's correct

nocturne tusk
#

idk how to do column vectors lol

leaden skiff
#

column vectors?

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oh you mean like in latex right, not for this problem

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$^nC_r$

fathom swallowBOT
errant merlin
#

Ah

surreal sapphire
#

there is a $\binom{n}{k}$ command

fathom swallowBOT
#

Lochverstärker

nocturne tusk
#

im gonna correct my thing just so it stops annoying me

fathom swallowBOT
#

Ninja

$\mqty(x \\ y \\ z)$
errant merlin
#

Nice

toxic gale
#

Is that a built-in thing or your own shortcut?

leaden skiff
#

built in

toxic gale
#

💀

errant merlin
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I've been using \bmatrix devastation

leaden skiff
#

part of the physics package

fathom swallowBOT
#

katie <3

leaden skiff
#

which is default in latex discord

leaden skiff
nocturne tusk
#

swag

toxic gale
#

You mean I didn't need to do \begin{pmatrix}x \\ y \\ z \end{pmatrix} this entire time? pandaOhNo

surreal sapphire
#

physics package devastation

errant merlin
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Next, can you state the limit definition of the derivative?

leaden skiff
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also in the phys package

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its based

brittle socket
nocturne tusk
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$\lim_{h\to 0}{\frac{f(x+h)-f(x)}{h}}$

leaden skiff
fathom swallowBOT
nocturne tusk
#

that looks weird

brittle socket
#

Ah yeah that works too

surreal sapphire
#

i have never seen this notation ever ninja

nocturne tusk
#

the limit

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it is down

leaden skiff
errant merlin
#

I've seen $_nC_k$

toxic gale
fathom swallowBOT
#

katie <3

surreal sapphire
#

in general i think you need good reasons to have superscripts before a symbol

nocturne tusk
#

how do I make it not be

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down

leaden skiff
surreal sapphire
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this isnt a good reason

toxic gale
surreal sapphire
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its not just fine, its correct

nocturne tusk
#

It irritates me

leaden skiff
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im dumb

nocturne tusk
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why is the limit

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down

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why is it so low

surreal sapphire
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because its a line in text

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its flush at the bottom

leaden skiff
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anyway, now try applying the limit definition to x^n

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to find its derivative

nocturne tusk
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im not doing all of that using the first principle in latex

leaden skiff
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lol, just copy ur old latex and change it where needed

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if you want write it on paper and send a picture i guess lol

nocturne tusk
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$\lim_{h\to 0}{\frac{(x+h)^n-x^n}{h}}$

nocturne tusk
leaden skiff
#

no this is not correct

leaden skiff
errant merlin
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let f(x) be xⁿ

nocturne tusk
#

wait no im stupid yeah

arctic grove
fathom swallowBOT
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katie <3

leaden skiff
#

yes!

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now can you expand (x+h)^n with the binomial formula

arctic grove
#

ninja teacher arcs huh

leaden skiff
#

im giving back to the community whatcanisay

arctic grove
errant merlin
nocturne tusk
#

$\lim_{h\to 0}{x^{n-1}\binom{n}{1}+\cdots +x^0\binom{n}{n}(h^{n-1})}$

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hope and pray

errant merlin
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Well done

arctic grove
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goooddd

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now do a lil cancelling

leaden skiff
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yes good job!

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yes

errant merlin
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Nice

leaden skiff
#

now we really wanna get rid of the h in the denominator, because if we apply the limit now we get 0/0 and thats indeterminate

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so can you cancel it out?

brittle socket
#

As a side note, using the binomial formula you can prove that $\frac{d}{x^n}{dx}=nx^{n-1}$ but only for $n \in \mathbb{N}$. Iirc, if you want to prove it for all real powers you can use logarithmic (impicit) differentiation.

fathom swallowBOT
nocturne tusk
#

cock

leaden skiff
#

it's not \x

fathom swallowBOT
#

katie <3

errant merlin
#

Getting close!

leaden skiff
#

yes!, now just apply the limit

nocturne tusk
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$x^{n-1}\binom{n}{1}$

fathom swallowBOT
#

katie <3

errant merlin
#

and what is $\binom{n}{1}$?

fathom swallowBOT
nocturne tusk
#

$nx^{n-1}$

fathom swallowBOT
#

katie <3

nocturne tusk
#

yooooo

errant merlin
#

🥳

leaden skiff
leaden skiff
nocturne tusk
#

swag ty

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now I know all of maths.

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all of it.

surreal sapphire
leaden skiff
errant merlin
#

You are now unstoppable

toxic gale
nocturne tusk
#

I watched a proof of the chain rule

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I understood it, but like

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how would they know to do that

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1 sec ill find the proof

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where does that second fraction come from 😭

leaden skiff
brittle socket
#

The transition btw the 1st and 2nd step is just a change of denominators

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instead of h at the first fraction, its moved to the second one

nocturne tusk
#

$\frac{g(x+h)-g(x)}{g(x+h)-g(x)}$

fathom swallowBOT
#

katie <3

leaden skiff
brittle socket
#

That just evaluates to 1

leaden skiff
#

they multiplied by 1

nocturne tusk
#

I know

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but like

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why represent it

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as that

leaden skiff
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ohh like how did they come up with it?

nocturne tusk
#

yeah

leaden skiff
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idk ¯\_(ツ)_/¯

nocturne tusk
#

lol

toxic gale
#

Normally it's just smart guesswork. In this case they want the first fraction to look like a derivative.

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So getting a g(x + h) - g(x) in the denominator would make the first fraction in the form of a derivative.

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But then since you can't randomly divide, you have to multiply, giving another fraction and rearranging it gives another derivative.

nocturne tusk
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I see

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yeah no I would have never come up with that

toxic gale
leaden skiff
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you get better with practice

nocturne tusk
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actually I think I owe myself a bit of lenience cuz like

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I had 2 lessons on proof by deduction and exhaustion

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one of which I missed

toxic gale
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But really the first thing you "should" think of here would be that we want to use the limit definition of the derivative with $f(b) - f(a)$, where $b = g(x + h)$ and $a = g(x)$. But that requires the denominator to be $b - a$ so we needa multiply and divide by $b - a$.

fathom swallowBOT
#

PhenomPlasma

nocturne tusk
#

that is the only proof ive ever done

toxic gale
#

Proofs are definitely not easy when you first start.

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I still find a lot of them hella hard.

nocturne tusk
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I had one like

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I forgot what it was but it involved prime numbers

surreal sapphire
#

i can confirm that i also find proofs hard

nocturne tusk
#

I had no idea where to start so I skipped it

toxic gale
#

Was it to prove there are infinitely many primes? That's usually the classic one they like to go through.

nocturne tusk
#

the mark scheme said I had to use exhaustion by representing prime numbers as (10n+1), (10n+3), (10n+7) & (10n+9)

#

i would have never fucking thought of that

toxic gale
#

There's a proof in Spivak's Calculus that pi is irrational and he just pulls these functions out of thin air.

nocturne tusk
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oh god dont remind me

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I started that book

errant merlin
surreal sapphire
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hmm

nocturne tusk
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I can hardly even do the first 5 questions on the first chapter

surreal sapphire
#

i dont think this is the original proof of irrationality

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so in this case its also easier because you know the result

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and then people just ask "can we prove this using wtv techniques"

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and its a lot easier if you know where you want to end up

toxic gale
#

Ah yes I definitely would've come up with these functions.

leaden skiff
#

what the fuck

nocturne tusk
#

there was a question like 3^x + x < 4

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that sounds easy right

leaden skiff
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to find all x that this is true for?

nocturne tusk
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find x given ghat

toxic gale
nocturne tusk
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yes

errant merlin
nocturne tusk
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Ik its like

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0 < x < 1

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but how do I show that

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wait no

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its just x<1

leaden skiff
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its just x < 1 right

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yeah

toxic gale
#

Oh wait yeah I'm dumb. You can solve it by observation.

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Increasing function.

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Pfft.

leaden skiff
#

yeah thats what i was thinking too, prove its strictly increasing

nocturne tusk
#

I googled it and it was using some weird ass functions

leaden skiff
#

then note f(1) = 4

toxic gale
#

Wait but if that's Spivak chapter 1 you wouldn't know calculus.

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Still though I guess you would know from high school thst 3^x and x slope upwards.

nocturne tusk
#

idk if I have the exact question on my phone

errant merlin
#

I think I have it

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Wait here

leaden skiff
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spivaks calc book is really a real analysis book in disguise

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afaik

toxic gale
#

Oh yeah Spivak Exercise 1.4(xii).

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Up to now the only Spivak I've read is the pi chapter (I think 16). kekw

errant merlin
surreal sapphire
#

you dont need calculus to show this is strictly increasing

toxic gale
#

Honestly it's an interesting proof.

leaden skiff
toxic gale
#

Technically it doesn't ask you to prove it's correct so.

leaden skiff
#

but wait

nocturne tusk
#

the only possible solution i could think of

leaden skiff
#

no i dont get it nvm

nocturne tusk
#

was to plot both graphs and see the intersection

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but idk it just dont seem right to me

surreal sapphire
#

3^(x+h) + (x+h) = 3^x *3^h + x+ h >= 3^x + x +h > 3^x + x for every h > 0 should work?

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you just need some kind of argument that 3^h >= 1

leaden skiff
errant merlin
#

Spivak defines exponentiation much later in the book so I don't think we're expected to show that

toxic gale
#

I don't think you need to be that rigorous at the start of Spivak to be honest.

#

I think it's probably just there to test your intuition or something.

surreal sapphire
nocturne tusk
#

oh well I havent touched spivak since that question

errant merlin
#

💀

nocturne tusk
#

idek all of precalc yet

surreal sapphire
#

maybe you do need some continuity argument bleakkekw

errant merlin
#

Is spivak a hard calc book or an easy analysis book

nocturne tusk
#

it is certainly a book

errant merlin
#

Definitely one of the books of all time

nocturne tusk
#

I think I still have some trig left to learn then I should be good for precalc

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like radians + sec cosec and such

brittle socket
#

Its not really anal from what I have heard

leaden skiff
#

i dread the day i have yo learn real analysis bleak

errant merlin
#

I guess It's a transition book

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From calc to analysis

nocturne tusk
#

damn its still weird to me

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that in just over a year from now ill be in uni

toxic gale
nocturne tusk
#

finally doing more than just learning how to model the growth rate of a tree

leaden skiff
#

im someone who doesn't really enjoy pure math

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so thats why im kinda dreading it lol

toxic gale
#

I mean maybe you'll learn better models for the growth rate of the tree. kekw

nocturne tusk
#

im the opposite

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applied is just really formulaic to me

surreal sapphire
#

if you study engineering you dont really have to do real analysis

toxic gale
#

I'm kinda in both camps. I like pure math a good amount but when it gets too abstract I tend to get a bit... lost.

nocturne tusk
brittle socket
leaden skiff
errant merlin
surreal sapphire
#

hmm

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your average physicists probably doesnt need a real analysis class either bleakkekw

leaden skiff
brittle socket
surreal sapphire
#

i feel like a lot of a real analysis class or just math classes in general maybe are focused on studying pathologies of the theory

toxic gale
#

Where I start struggling is when I have difficulty understanding the need of definitions. Like I can understand concepts like partial derivatives, eigenvalues, Jacobians, etc just fine, because I can attach it to some purpose. But when I have to define left cosets I'm just wondering OK how in the world is this gonna matter.

surreal sapphire
#

and an engineering student just doesnt care about that

leaden skiff
#

im not planning on taking like a college class on ranal btw

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im gonna self study

surreal sapphire
#

and even in physics a lot of the pathologies dont appear

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tho tbf i have a bad view of physics

leaden skiff
#

after i learn like algebra and la and stuff

nocturne tusk
#

self studying is too hard I can only learn stuff from classes

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but I only have 4 classes a week

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and im missing 3 this week 😭

surreal sapphire
#

you should learn NT instead sotrue

leaden skiff
#

im mostly exaggerating btw

tiny forge
errant merlin
surreal sapphire
#

tbf a good class will motivate (most) definitions

nocturne tusk
#

my adhd doesn't let me work on something for more than 5 minutes if I dont get it instantly

leaden skiff
#

im just worried im gonna suck at it and feel like a moron bleak

errant merlin
#

Everybody agrees real analysis is hard

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So don't worry if it doesn't click with you instantly

surreal sapphire
#

being bad is the first step of becoming good

leaden skiff
#

like ok the reason i really dread it is because i tried it once like a year ago and i almost cried because i couldnt do an epsilon delta proof opencry

halcyon frigate
nocturne tusk
#

I dont like people putting difficulty on things

halcyon frigate
#

HELOPP

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help pls

toxic gale
#

I don't think anyone can do epsilon-delta the first time they see it. 😂

nocturne tusk
#

cuz like I often struggle with shit and people just go "this is easy lol"

toxic gale
surreal sapphire
halcyon frigate
#

help bro pls

leaden skiff
charred mortar
#

Also chances are those ppl probably spent a lot of time on the subject before it “felt easy”

toxic gale
#

Is RA focused that much on epsilon-delta?

nocturne tusk
charred mortar
#

It has quite a bit

toxic gale
charred mortar
#

But there’s certainly other stuff involved too

errant merlin
#

Actually

charred mortar
#

It pops up here and there I’d say

errant merlin
#

Sometimes you do compute limit using epsilon delta

toxic gale
charred mortar
#

Yeah

surreal sapphire
#

epsilon delta is like

errant merlin
surreal sapphire
#

you have to learn to walk before you can run

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later your arguments are more intuitive

toxic gale
#

I flipped through an RA book and didn't actually see that much of it.

surreal sapphire
#

"ok so sending this guy to 0, this guy also goes to 0, so ..."

charred mortar
#

But yeah it’s often in the context of limits of some form or another

leaden skiff
#

and epsilon delta is where i learned i didnt even know how to crawl opencry

toxic gale
#

I've tried understanding epsilon-delta so many times that it is intuitive to me now.

charred mortar
#

And there’s definitely a bunch of other stuff involved with RA yeah

tiny forge
#

Its good practice for when you go on to do analysis in more abstract spaces, where you really are going to need to use ε-δ for a lot of arguments

surreal sapphire
#

the thing is you need to be able to formally check your own work

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so you have to know the definitions

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later you can do "intuitive" arguments

nocturne tusk
#

idek what a limit is, I just assumed its like "as x approaches this number, the max/min value this function approaches is...."

surreal sapphire
#

but you need to learn to be self critical and be able to check your own arguments formally when needed

charred mortar
#

Later on you’ll also be able to be more flexible with the epsilons too

toxic gale
surreal sapphire
#

because again, intuitive ideas dont always work

leaden skiff
surreal sapphire
#

and a real analysis class will spend considerable amount of time and showing you pathologies

nocturne tusk
#

is it like

surreal sapphire
#

so you understand that

nocturne tusk
#

the closer x is to y, the more accurate it becomes

leaden skiff
surreal sapphire
#

later, you can do more things solo, but you still need sanity checks from peers

leaden skiff
#

yeah. thing is i dont want a math major, but i still want to learn these things.

toxic gale
#

That we can make f(x) as close as we want to L (this is made rigorous by saying that we can make |f(x) - L| < e for every positive e), provided x is sufficiently close to a (made rigorous by saying there exists d such that |x - a| < d). I think that's essentially the definition of limit almost done.

charred mortar
surreal sapphire
#

where i am physics majors can just take the math classes that math majors do

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same for engineering

charred mortar
#

It can be very hard at the start to know if what you’re doing is right

torn willow
#

Epsilon delta is a useful tool for stuff

surreal sapphire
#

its more work but if they are interested

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so i dunno, maybe this is possible?

leaden skiff
#

idk if this is possible for me but maybe ill look into it?

charred mortar
nocturne tusk
#

only an hour till I am in Glasgow woo

leaden skiff
#

i mean maybe i could try to find a way to study with people here

errant merlin
#

Analysis study group? 😳

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I'm down tbh

charred mortar
#

You could also ask for a proof check maybe

errant merlin
#

Need summer activities

charred mortar
#

In some of the channels

surreal sapphire
#

god i wish i had more free time now that its summer opencry

nocturne tusk
#

I need other people to make me study, but everyone I know will either not know enough or be way above my level

surreal sapphire
#

i realize i am shitposting on discord for an hour already

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but i am actually editing while doing so!

torn willow
#

idk if I should do ML tbh

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The math seems very advanced and analysis-y

leaden skiff
#

i thought it was just la

torn willow
#

But I just don't feel like doing analysis

leaden skiff
#

and calc

torn willow
#

If you want to do ML rigorously,you need analysis

surreal sapphire
#

you need to know analysis, yes

leaden skiff
surreal sapphire
#

and then its a ton of numerics

torn willow
#

Just plug-and-chug feels stupid to me

#

ML feels very unsexy

leaden skiff
charred mortar
#

Tbh some of the numeric stuff I’ve come across feels like putting in actual numbers instead of an epsilon

nocturne tusk
#

quick unrelated question

torn willow
#

Also MATLABdevastation

nocturne tusk
#

what does advanced number theory consist of

leaden skiff
#

numbers

torn willow
#

Too broad

nocturne tusk
#

no way

surreal sapphire
#

it depends

torn willow
#

Probably rings

nocturne tusk
#

just like

leaden skiff
#

its like, number fields tho right

nocturne tusk
#

examples ig

torn willow
#

and integrals

surreal sapphire
#

number fields is an example, yes

charred mortar
#

All I know is that it can get ultra hard

surreal sapphire
#

thats like the original starting point of modern NT

torn willow
#

Well it uses galois theory ig

surreal sapphire
#

so uh katie

leaden skiff
#

god everything in math uses everything else

surreal sapphire
#

you know how there is the complex number i

nocturne tusk
#

yes

surreal sapphire
#

originally NT studies the integers Z

torn willow
#

So How does stats look like

#

Is it also tons and tons of analysis

surreal sapphire
#

an old question you may want to ask is which numbers can be written as the sum of two squares

compact tartan
surreal sapphire
#

so x^2 + y^2

#

one thing you can notice that over the complex numbers this can be factored as (x+iy)(x-iy)

nocturne tusk
#

uhhhh

compact tartan
#

you could be doing the kolmogorov theorem on the convergence of the empirical distribution, or you could be like hurr durr F-test goes here

surreal sapphire
#

and this multiplicative way of writing this is much easier to study because we have a lot more tools

#

but there is no complex number i in the integers

#

so you can think of "just add it to the integers"

#

and this gives you numbers of the form a+bi where a and b are only allowed to be integers

#

now this turns out to behave somewhat like the regular integers

compact tartan
#

in stats there's some neat theory connecting estimators and tests, bayesian stuff etc, for describing "optimal" approaches

#

there's also a lot of measure-theoretic analysis

surreal sapphire
#

and you can define notions of what it means to be a prime number

compact tartan
#

and then there's the hard applications to actual data

nocturne tusk
#

im gonna be honest

torn willow
#

Oh damn, analysis is everywhere

surreal sapphire
#

and in fact classifying how primes behave in this thing will answer the original question

#

and this leads to more general questions

nocturne tusk
#

i lost you at "multiplicative"

surreal sapphire
#

oh well

#

the multiplicative structure of the integers is in many ways nicer than the additive

#

you have for example the fundamental theorem of arithmetic

#

so every integers can be written uniquely as a product of primes

#

questions about representing some number as a sum are much harder

compact tartan
#

I'd argue that's very far from "nicer than the additive"

surreal sapphire
#

its just a vibe for now

nocturne tusk
#

I think

compact tartan
#

prime factorization yields an iso between N_>1 and N^infty

nocturne tusk
#

I need to learn stuff

compact tartan
#

the latter has much more space to miss

#

so you get much more "no" answers

#

to ask interesting questions about addition you have to start with fucked up sets

#

hence the hardness

surreal sapphire
#

and writing x^2 + y^2 = (x-iy)(y+iy) is kind of like a factorization

#

oh well, i care about arithmetical questions and writing things as products is nice, writing things as sums is not nozoomi

compact tartan
#

idk, weird argument

nocturne tusk
#

I need to find friends who are as dumb as me so I can talk to them without being incredibly confused

surreal sapphire
#

i tried SadCat

nocturne tusk
#

I think I probably went a bit out of my depth asking about that

leaden skiff
nocturne tusk
#

I meant more like

#

more than just "a + b = b + a"

surreal sapphire
#

i dont know, those things were studied before calculus was invented

#

albeit with different language and generality

nocturne tusk
#

but yeah no I should defo learn the basic shit beforehand

#

I must learn the quotient rule...

surreal sapphire
#

i actually love the sum of two squares question because its so simple (and looks kinda dumb) but can lead to a lot of rich mathematics

nocturne tusk
#

im sure thats great and all but my brain can't comprehend it

#

one day maybe

leaden skiff
nocturne tusk
#

ill just do what I did with the product rule

#

and Google it

arctic grove
#

fuck the quotient rule, all my homies hate the quotient rule

toxic gale
#

I never remember the right order. kekw

#

I always use the quotient rule to differentiate 1/x to remember which term comes first. kekw

leaden skiff
neat lintel
#

Left dright minus right dleft

leaden skiff
#

its a rhyme to help you remember, thats what i use

neat lintel
#

@leaden skiff 3b1b?

leaden skiff
#

yes

neat lintel
#

Same

errant merlin
#

Why remember the quotient rule when you can successively use the product, power, and chain rule everytime

toxic gale
#

I'm pretty sure it's (u/v)' = (vu' - uv')/v² but I get paranoid.

leaden skiff
#

so true

neat lintel
#

Using the product rule with the chain rule is good

#

For powers other than - 1

toxic gale
#

I just don't do derivatives much anymore.

#

When I was still in high school we rarely got straight differentiation questions because I think the teachers figured out it was too easy. Differentiation usually only appears as an application (optimization) problem.

toxic gale
leaden skiff
toxic gale
#

Currently reading Lakins' The Tools of Mathematical Reasoning.

#

It's used at my uni for discrete math but its an intro to proofs book.

bright hill
#

@deep mango I remember you saying that every convergent sequence is a Cauchy sequence in a metric space

#

It just struck me

#

How tf do you make sense of convergence without a metric?

deep mango
#

What was that about wew

deep mango
sleek wing
deep mango
#

A sequence x_n converges to a point x if for every open set U containing x, there is an N so that x_n is in U whenever n > N.

#

This is the same thing as the usual definition of convergence in metric spaces.

sleek wing
#

yeah you use the funny neighbourhood def

deep mango
#

That definition talks about being in open balls

sleek wing
#

pftftft balls 🤣

bright hill
#

Oooo

#

That makes sense

deep mango
#

"x_n converges to x" means "x_n eventually stays in any neighborhood of x"

bright hill
#

Although, I'll need to learn about non-metriciazable spaces before I fully understand why we need that definition

#

Coz I have no idea what those look like lel

neat lintel
#

Hello! I'm trying to further increase my skill of problem solving, do you guys know any resources / books that might help me achieve this? Thank you.

fervent pebble
#

imagine doing the quotient rule

#

it's literally the product rule

#

and memorizing a whole new fkin algorithm is not worth it

fair mural
deep mango
#

you apologize to wew even though your laughter is at my expense.

bright hill
#

it's geared towards competition math

neat lintel
neat lintel
bright hill
#

ye, probably

neat frost
deep mango
#

No it's actually dope

neat frost
#

I sincerely doubt that

fervent pebble
#

idk slurp have u seen rycs hair

neat frost
#

Oh shi you’re right

deep mango
bright hill
#

I have no idea what I just read

stark charm
#

if i were you i wouldnt let that slide

#

thats just me though

deep mango
#

Humor is transactional

#

I am an endless hoard of patience

#

Better to joke about me than about someone who has a chance of being hurt by it.

valid compass
#

Haha ur profile pic is a bird ahahaha lol gottem

dense belfry
#

Lol gay bird

cyan goblet
dense belfry
#

You pay in reputation

cyan goblet
#

good repsonse

deep mango
#

Lol

dense belfry
#

And you have no idea what the price is a priori

#

I'm pretty good at one liners tbh

summer sandal
#

I have been seeing those types of comments online now for some reason.

#

It’s always funny; that is just me tho.

dense belfry
#

I don't think the comment was very socially aware tbh

summer sandal
#

I believe.

dense belfry
#

I don't think it was

#

But maybe I'm wrong

summer sandal
#

Instigating, is what I believe it’s called.

dense belfry
#

I see

summer sandal
#

It’s a popular trend online.

dense belfry
#

What does that entail?

#

Trying to start a fight?

summer sandal
#

Nothing much, just jokes. Unless someone takes it too far.

#

By being annoying.

dense belfry
#

I mean instigating means trying to start a fight

summer sandal
#

I know.

#

Just I think they meant is as a joke here.

dense belfry
#

Okay

#

Well whatever

summer sandal
#

Lol, yeah.

stark charm
#

its just more popularized by ppl online now

summer sandal
#

Yeah, been seeing it online now. That why I decided to comment.

dense belfry
#

Can you please explain what it is?

summer sandal
#

Not sure why it became popular.

stark charm
#

not much else

dense belfry
#

Trying to start a fight?

#

That's gross

stark charm
#

lol

#

emma catchphrase

dense belfry
#

I have many catchphrases

#

They change pretty often

stark charm
#

i like it

dense belfry
#

I mean I start debates pretty often

#

I guess

stark charm
#

thats gross

dense belfry
#

I don't like fights though

#

Lol

stark charm
#

🤑

summer sandal
#

Just to let one know, I wasn’t in supports for any fights. I thought it was funny since I have been noticing those comments for a while in funny contexts.

dense belfry
#

I think the fact it's a trend is cringe tbh

#

Big reddit bro vibes

summer sandal
#

YouTube, but I don’t use Reddit.

#

Well, I do but not like discord.

dense belfry
#

Oh you think that's a more accurate description of the vibes?

#

Discord is nice

#

Honestly it's changed a lot of people's lives for the better I think

#

Hot take

summer sandal
#

Definitely, I used it a lot in past and people helped me a lot.

dense belfry
#

Discord is the best place for talking if you have ADHD lol

#

Everyone talking over each other

#

No need to wait

#

So good

azure nymph
#

Chat rooms are kinda cool in that way where you can have multiple different conversations going on and it's mostly fine

summer sandal
#

Top reason I use discord is due to its simple layout. The contents is not too much unlike Reddit and twitter.

dense belfry
#

Oh I like having multiple conversations at once in the same channel

#

Lol

#

Maximize confusion

ancient flame
#

lemme add to the confusion

summer sandal
#

That I can do, not sure how I manage to do it.

ancient flame
#

primarily bc emma is here

#

help what's the difference

#

ffs

summer sandal
#

I think there is bigger context to this.

ancient flame
#

not really

#

https://en.m.wikipedia.org/wiki/Maxima_and_minima

summer sandal
#

What is the definition of minimal element here?

ancient flame
#

I forget how to do it

#

that's precisely what im confused about

dense belfry
#

Yeah this is exactly local vs global

#

There being an element which is below every other element is a global minimal element

#

A local minimal element would be one so that there are no elements below it

#

I can give a concrete example

ancient flame
#

that would be appreciated

dense belfry
#

Take the partial order with three elements

#

a, b, c

#

So that a <c and b<c

ancient flame
#

what's the difference between partial order and total order

dense belfry
#

And that's it

#

A total order has every element is comparable

#

In the example I gave that's not true

#

a is not comparable to b

ancient flame
#

ohhhh

#

okay

dense belfry
#

Oh I can post a picture

#

For this order

#

One sec

leaden torrent
#

anyway, the point in emma's example is that nothing is smaller than a (so a is minimal) but a is not smaller than every other element (it's incomparable with b)

peak tide
#

standard example of a partial ordering that is not a total ordering: the collection of all subsets of a set, ordered by inclusion ($\subseteq$)

fathom swallowBOT
#

OurBelovedBungo

leaden torrent
#

and we could interchange the roles of "a" and "b" in that sentence

#

and get the same fact

#

(i.e. a and b are both minimal)

ancient flame
#

oh ok

dense belfry
#

Yes

#

However c is a maximum element

ancient flame
#

that makes sense but is confusingly complicated at the same time

dense belfry
#

I have a picture

dense belfry
#

If I can find a pen

ancient flame
#

okay lol

dense belfry
#

There

leaden torrent
#

the empty set is smaller than all sets

#

in this ordering

#

so it's both minimal and least

#

still a good example of a partial order though.

dense belfry
#

Just this

#

Lol

ancient flame
#

ohhhh

#

I see

dense belfry
#

Yeah

#

This is how you draw partial orders

#

Btw

ancient flame
#

I see

#

alright that all makes sense

#

ty guys :D

azure nymph
dense belfry
#

Yes

leaden torrent
#

digraphs are partial orders

#

well

#

as long as you avoid loops

dense belfry
#

They are preorders

leaden torrent
#

correct

errant ridge
slim veldt
#

guys join vc

neat lintel
#

Okay so

#

I've seen PPL say that

#

You can't directly compare two complex numbers

#

Is taking the modulus (or magnitude) of both and then comparing them valid?

surreal sapphire
#

is i greater than 1?

neat lintel
#

Well its modulus is equal to 1

surreal sapphire
#

so?

neat lintel
#

Well we can't directly compare a complex number with a real

#

Complex is 2 dimensional while reals are 1 dimensional

surreal sapphire
#

what

forest jackal
surreal sapphire
#

every real number can also be thought of as complex

neat lintel
static loom
#

the word "compare" here doesn't mean it in the colloquial sense if that's the confusion

forest jackal
#

you can cook up lots of "orders" if you just want to satisfy the properties an order should have (reflexivity, transitivity, antisymmetry)

#

For instance you could use what is called the dictionary order, and say that a+bi < c+di if either a < c (in the sense of real numbers) or a = c and b < d.

neat lintel
#

Ooh

forest jackal
#

but the point is that this order does not behave well with respect to the operations of multiplication and addition.

neat lintel
#

So there is some sort of limitation if I define an order for comparing such numbers

forest jackal
#

yes, to be precise you cannot pick an order such that the following two properties hold:

  1. z < w => z + c < w + c for any complex z,w,c.
  2. z > 0 and w > 0 => zw > 0.
neat lintel
#

True

forest jackal
#

you can think of these properties as saying that an order is "compatible" with addition and multiplication in your field respectively.

neat lintel
#

Thanks 👍

forest jackal
#

no worries

#

(By the way, it's an easy but worthwhile exercise to prove that no such order can exist. If you can't see why immediately, I suggest you think about it for a couple of minutes.)

neat lintel
# forest jackal (By the way, it's an easy but worthwhile exercise to prove that no such order ca...

I've been thinking about this for a while, and here's my conclusion:

  1. Complex numbers are not ordered fields, i.e., total orders cannot be imposed on this field:
    Say we impose a total order ≤ on C, and assume C is an ordered field.

In any ordered field, the multiplicative identity is greater than the additive identity.

So, 0≤1
This implies i ≤ 0 ≤ 1 or 1 ≥ i ≥ 0. So i≤0 or i≥0

Taking i≤0,
In an ordered field, squares are always non-negative, i.e., 0 ≤ a² for any element a in the field. This is one of the properties of an ordered field.
Hence squaring both sides of i ≤ 0, we get -1 ≤ 0 => i² ≤ 0. This contradicts the property of ordered fields, hence contradicting our assumption.

Taking i≥0,
Implies -i ≤ 0
Implies (-i)² ≤ 0
Implies -1 ≤ 0,
which again contradicts the property of ordered fields.

  1. This also contradicts the axiom a.b ≤ c.b, where b is any non negative number.
    Say 1+2i ≤ 1+3i (by comparing component by component)
    Multiplying both sides by i (positive number)
    We get -2+i ≤ -3+i
    And -2 is not less than -3, contradicting this property.

Hence, a total order cannot be imposed on Complex Field. Partial orders like ≤ where:
a+bi ≤ c+di if a≤c; or bi≤di if a=b,
can be imposed, but have limitations.

Hence, no such total order exists.

forest jackal
neat lintel
#

Thank you for giving me such a wonderful excercise 👍

forest jackal
#

no worries, glad you were able to get something out of it!

forest jackal
# neat lintel Thank you for giving me such a wonderful excercise 👍

By the way, something you might find cool if you don't know it already:

The ONLY complete totally ordered field is the real numbers.

(Completeness here is the statement that any bounded set has a least upper bound. Don't worry too much about it if you haven't seen this property before, but roughly it means it doesn't have "holes" in it like the rationals do.)

maiden bear
#

oh that's a nice one

neat lintel
#

Ohh I see
👍

maiden bear
#

a bit tricky if you don't know the "idea" to the proof maybe

forest jackal
#

Oh yeah I wasn't suggesting this second thing as an exercise, it didn't sound like the kind of thing Pencil was studying. Just mentioned it as a strong/somewhat striking result along the lines of his initial question.

ancient flame
#

Good morning, fellow individuals on the Mathematics Discord Server.

neat frost
#

Ily!

ancient flame
#

Hello, Slurp and Idris. How are you both doing today?

ancient flame
# neat frost Ily!

Excuse me Slurp, I do not seem to understand the meaning of "Ily." Is that a health condition?

neat frost
#

😭

#

My heart…..

ancient flame
#

That is a heart condition? I advise you to speak to your doctor as that is very serious.

neat frost
#

So basically for my assignment they gave us a corpus of texts and there seems to be quite a few texts about porn

ancient flame
#

That seems to be very interesting. Please enlighten me about pornography.

neat frost
#

Gmod stop acting like a fucking nerd

ancient flame
#

Excuse me, that is inappropriate behavior for this community.

deft flame
#

what kinds of functions are there other than polynomial functions?

ancient flame
#

There are exponential and trigonometric functions, for example. These can be represented by infinitely long polynomials, but they look different.

neat lintel
#

function that connect every person to his biological father

#

that technically is a function too

#

though it isn't taht useful

brittle socket
#

So you could say ${ (1,1) }$ is a function

fathom swallowBOT
brittle socket
#

In fact $\varnothing$ is a function

fathom swallowBOT
brittle socket
arctic grove
brittle socket
arctic grove
#

dont sully me i dont get what u are saying

neat lintel
#

$\varnothing$ maps to itself

fathom swallowBOT
#

Llama calculus

neat lintel
ancient flame
#

im good

#

I gave up trying to be formal

#

loL

fair mural
#

good, it was weird and not funny

open aspen
#

doing your complex impersonation?

ancient flame
#

yeah

ancient flame
#

I did it for a day a few days ago

#

can't do it again

#

lol

open aspen
#

are buisnessmen supposed to be professional and formal?

neat lintel
# deft flame what kinds of functions are there other than polynomial functions?

In general a function is defined as a relation, which is a subset (or equal to) the Cartesian Product of the Domain and Co-domain, and both could be any algebraic structures (Vector Spaces, Rings, Groups or even Sets). If algebraic structures are involved, we take the Cartesian Product of the underlying sets of these algebraic structures.

You can define a function as whatever as you like. Let A = {1,2,3} and B = {Coca-Cola, Chips, Amogusflonshed}
Their Cartesian Product is a set of all ordered-pairs (a,b) where a belongs to A and b belongs to B [just like on Cartesian graphs when you label points. Keep in mind (a,b) ≠ (b,a) since they're "ordered"]

A relation is what we call a function, though not all relations are functions. Relation is a set of ordered-pairs, a subset to A×B (Cartesian Product), where between a and b in an ordered pair, there exists a unique relation between them. Like a=b, a+b is even, and so on.
Here I'll define my relation R = A×B = {(a,b) | a = b}.
That's your function right there. For each a, there exists a b where (a,b) is in R and if (a,b) = (a,c), then b=c, which is true. These are the two conditions for a relation to be a function. R(a) = b, where b can be thought of as the "mapped output of a".

So R(3) = Amogusflonshed

So you can create any function you like under these conditions.
Apart from polynomial functions, you have constant function, dirac delta function, kronecker delta function, dirichlet function, absolute value function, transcendental functions (like sin(x), cos(x), log(x), e^x) and tons of others

fair mural
open aspen
#

idk if formal -> professional; I can be formal and very rude, which wouldnt be professional

#

Not so sure about the converse

charred mortar
#

I feel like it depends on the setting

open aspen
#

in which case they are not generally equivalent

next schooner
#

Also this definition of a function as a univalent total binary relation is, while correct, totally obtuse for someone who hasn't seen anything beyond polynomials

ancient flame
next schooner
#

Much better to define a function in the usual manner, as a mapping between sets

neat lintel
ionic star
#

they meant correct

#

incorrect just sounds like correct, so you mix them up sometimes

lunar spear
#

hes using hard words like also, this and is

next schooner
#

Lol

neat lintel
#

Oh lol xd

fair mural
#

@next schooner i need a new rat fact

errant ridge
#

rats can hold their breath for upto 3 minutes

#

don't ask me how I know.... bsully3

ancient flame
#

psychologist moment

void wave
tall badge
#

@brittle socket @arctic grove @neat lintel theyre not exactly functions if one requires a function's data to include a domain & codomain

modest rune
#

(as one should)

brittle socket
velvet dagger
#

Uh huh

#

Yeah you def guessed so

arctic grove
#

yes i did!

arctic grove
velvet dagger
#

@arctic grove uh huh uh huh uh huh

arctic grove
#

that really is why i was confused

bright hill
#

ikr

#

dami is a bully

#

+1 respect point

velvet dagger
#

ur face is a bully

arctic grove
azure nymph
#

What do you guys think is more efficient 6.5 hours of sleep 7.5 or 5.5

tall badge
azure nymph
#

Also does anyone have a good schedule app I wanna use my time better

tall badge
#

its just that in these cases the domain & codomain werent stated

arctic grove
tall badge
#

like to fill in the details of the 2nd example, the emptyset can be considered a function from the emptyset to any set

arctic grove
brittle socket
#

Yeah but btw $f: A \rightarrow \varnothing$ is not a valid function for nonempty A

fathom swallowBOT
brittle socket
#

just as a side note

neat lintel
#

Yes

#

Hmm but what about

#

$f: A \rightarrow {{\varnothing}}$

fathom swallowBOT
#

Pencil/Idris

neat lintel
peak tide
#

certainly allowable, as is $f : A \to {\emptyset}$

fathom swallowBOT
#

OurBelovedBungo

neat lintel
#

👍

#

Yeah I forgot ∅ is itself a set lol

peak tide
#

yep

rose dock
#

although for me it's probably close to 8.5

arctic grove
#

anything around 8 hour is good

neat frost
#

What does “efficient” mean in this case?

#

Pretty sure teenagers are supposed to get between 8 and 10 hours of sleep

#

So if you meant “healthy” then none of those

arctic grove
neat frost
#

No

#

It’s 8 and 10 not inclusive

#

Gotta make sure you at least get 8 hours, 1 minute

arctic grove
#

ofc

#

lol

#

but yeah u need at least that much sleep

#

and at no point in ur life do u not need that much sleep

deep mango
#

I got 5

#

That's more than enough

#

Stop wasting your time asleep lazies

neat lintel
#

5-6 hours is more than enough actually when you are in highschool

deep mango
neat lintel
#

Wat

deep mango
#

I hope you are trolling the troll

neat lintel
charred mortar
#

Sleep deprivation is not good

rose dock
#

unfortunately it's normal for a lot of high schoolers

charred mortar
#

Yeah alas it is

#

In highschool my priority was usually to sleep really

#

But I know many of my classmates were sleep deprived (and understandably so)

#

For me I’d be willing to potentially do some hw or whatever badly if it meant I could get my proper sleep in

ripe wasp
#

when should i be sleeping during the summer?

#

i sleep around 11:30-12 then wake up at around 9

charred mortar
#

I tend to just sleep at a reasonably regular time, say 11 pm to 8

#

That seems fine to me

neat lintel
#

I sleep at 12 am at wake up at 6:30 or sometimes at 6 am

ripe wasp
#

one of my friends sleep at literally 8 pm then wake up at 4...

rose dock
ripe wasp
#

im happy for him, his work paid off

#

he got into a very prestigious boarding school

bright hill
#

sooooo, checks out, grampa

deep mango
#

Well

#

Judging by my state right now

#

I need to sleep more monkey

neat frost
deep mango
#

Yes

neat frost
#

Wow

#

Guess you have less stuff to do as you get older

bright hill
neat frost
bright hill
neat frost
#

I understand

#

I was referring to how you immediately jumped to Reddit

#

You were obviously projecting

bright hill
#

I don't sleep at 5 am.

deep mango
#

I browse reddit

#

But I don't sleep at 5am

bright hill
#

Ye, I found your account the other day lel

deep mango
#

I sleep at midnight and just wake up at like 6

#

😮‍💨

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yes I made an account so that people could see it if they wanted

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since all i do is post on the big brother and survivor subreddits

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and give ridiculous takes about reality television

bright hill
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Lel

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Based

bronze pelican
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Ryc stands for reddit yuser cringe

bright hill
errant ridge
arctic grove
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smh

bright hill
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It's true tho

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You can look it up

arctic grove
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its not true

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u always need 8 hours of sleep, no matter how old you are

surreal sapphire
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infants needs a lot more

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and sleep times go down with age in general

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this is the better image

bright hill
arctic grove
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its still around 8

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fairly close to it

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it didnt get to 5 hours

surreal sapphire
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ye

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there are some people that can do with 5 hours

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there is some genetic predisposition

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but its not the norm

arctic grove
arctic grove
surreal sapphire
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i mean this is still true

arctic grove
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those people can get rem sleep quickly

surreal sapphire
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sleep required goes down

arctic grove
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but not to 5 hours

surreal sapphire
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there is also thing thing that if you sleep more often, you need less sleep

arctic grove
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true

surreal sapphire
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the general ideas is that the deciding factor is REM sleep, not time spent asleep

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and if you sleep more often, you get more REM sleep

bright hill
arctic grove
bright hill
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Ok, maybe when I was messing with ryc

arctic grove
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thats what i was talking about!

bright hill
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Does anyone know how edd is doing?

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I miss edd sadcat

ancient flame
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wait where is he

bright hill
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I dunno

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Ryc said they were on a break way back

ancient flame
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oh ok

ancient flame
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she sleeps like 10 pm - 3 am

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literally

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meanwhile I sleep 3 am - 10 am

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and I am still tired af

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my body needs like 9 hours of sleep

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I was sleeping well at the start of summer but my dad kept getting mad I slept until 11 am

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actually now I wake up at like 9 am

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I keep trying to sleep earlier but I can't