#serious-discussion

1 messages · Page 475 of 1

compact tartan
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now we just have to come up with a way to compute $$e^? = (e^w)^2 + e^c$$

fathom swallowBOT
compact tartan
#

the squaring part is obviously easy, the fun part is in the addition

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$$ae^{ib} + ce^{id} = \sqrt{a^2 + c^2 + 2ac\cos(d-b)}e^{i<atan2>(c \sin(d-b), a + c\cos(d-b))}$$

fathom swallowBOT
compact tartan
#

so we get
$$e^{p+ib} + e^{q+id} = e^{\log\left(\sqrt{e^{2p} + e^{2q} + 2e^{p+q}\cos(d-b)}\right) + i<atan2>(e^q \sin(d-b), e^p + e^q\cos(d-b))}$$

fathom swallowBOT
compact tartan
#

now here we get to branch on p < q or p > q

pale orchid
#

how come

compact tartan
#

well if p >> q these expressions are going to be inaccurate

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$$\log\left(\sqrt{e^{2p} + e^{2q} + 2e^{p+q}\cos(d-b)\right) =$$ $$=\begin{cases} p + \frac{1}{2}\log\left(1 + e^{2q - 2p} + 2e^{q-p}\cos(d-b)\right) & ,p \ge q \ q + \frac{1}{2}\log\left(1 + e^{2p - 2q} + 2e^{p-q}\cos(d-b)\right) & ,p \le q \end{cases}$$

fathom swallowBOT
#

mniip
Compile Error! Click the errors reaction for more information.
(You may edit your message to recompile.)

compact tartan
#

idk where the error is

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but yea, this is really good because the e is always taken to a negative power

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serving as a correction to 1

pale orchid
#

that's clever

compact tartan
#

you can do that same for the atan2 part

vivid halo
#

god I remember trying to do optimizations like this to my holomorphic dynamics plotter I wrote years ago

compact tartan
#

just use mpf

turbid epoch
#

I feel intellectually outpaced in this discord chat.

vivid halo
#

I mean it was a programming class project so I did everything from scratch in C++

pale orchid
compact tartan
#

yea bignum arithmetic is one thing I know not to do by hand

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libgmp is just too good

turbid epoch
#

Anyone took analysis here?

sick burrow
#

scratch

vague lion
#

does this remind anyone else of a fruit lolly

compact tartan
#

sigh

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I understand type 4 functions but I don't understand the coordinate system it uses sadcat

pale orchid
#

i tried googling type 4 function and all the results are about type 4 collagen, so i can't help you

toxic schooner
turbid epoch
#

Too late to flaunt Calc 1 prowess, too early to understand Analysis.

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Despair

sick burrow
compact tartan
#

ok it's pretty stupid

wicked ore
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Literally what is this

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I’m trying to think of a set that could possibly satisfy these conditions

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for all x in A, x and A are disjoint
for all x, y where x ≠ y, then x is in y or vice versa
if x is in y and y is in A, then x is in A

vivid halo
#

the natural numbers are a good example of this, suitably constructed

zinc basin
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@vivid halo where I can get 10th class solutions?

wicked ore
compact tartan
#

ok I made a better and more compact mandelbrot in latex

vivid halo
#

like the Von Neumann construction of the natural numbers

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where it's like

wicked ore
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Von neumann naturals didn’t work at all

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Oh what

compact tartan
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all von neumann naturals satisfy this condition

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so does the set of all von neuman naturals

wicked ore
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But 2 intersect 1 = {Ø, {Ø}} intersect {Ø} = Ø right? I feel like I’m being like super dumb rn

vivid halo
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{Ø, {Ø}} intersect {Ø} is {Ø}

compact tartan
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2 intersect 1 = 1

wicked ore
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Oh shoot

leaden torrent
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🧠

wicked ore
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Yeah intersect is the set of common ones

compact tartan
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not sure what this has to do with anything though

wicked ore
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Nah i was just testing them out a bit

vivid halo
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yea so the naturals form the first infinite ordinal, \omega_0

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each Von Neumann natural forms a finite ordinal contained in \omega_0

wicked ore
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Contained in meaning subset right

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That makes sense

vivid halo
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yea

wicked ore
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Would it be weird to write that N = omega_0 ?

vivid halo
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it depends on what structure you're considering

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usually N refers to just the underlying set

wicked ore
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I’m trying to understand the difference between ordinals and cardinals

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Ok

vivid halo
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\omega_0 refers to the underlying set along with the order relation

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cardinals are sets considered up to bijection

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whereas ordinals are sets along with a well order relation considered up to order preserving bijection

turbid epoch
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Are there any functions f:N -------> R that are one-to-one?

vivid halo
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sure, the obvious inclusion

turbid epoch
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Hmm, but isn't the condition for one-to-oneness the fact that both sets have the same cardinalities?

vivid halo
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no not at all

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any inclusion is one to one

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just not onto

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one to one and onto means bijection and then yea in that case you need same cardinality

wicked ore
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I think he has a definition that one to one is bijective

turbid epoch
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Both a surjection and a bijection.

compact tartan
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I hate the terms "one to one" and "onto"

wicked ore
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I like how they sound a little closer to their meaning, but after using the -jective words enough times, it becomes intuitive anyway

compact tartan
#

how is "onto" closer to its meaning?

deep mango
wicked ore
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Like you’re putting something big onto something small

pale orchid
wicked ore
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When you learn that stuff for the first time, it’s just a bit easier

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But it’s stupid because you confuse injection and bijection

devout nacelle
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I'm okay with both but I prefer injective/surjective/bijective over the alternatives

compact tartan
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mono/epi/iso thinkies

sick burrow
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All injections are bijections into their image sotrue

wicked ore
sick burrow
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Kinda?

compact tartan
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cardinals are sets modulo bijection

wicked ore
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ok wait then what is it

compact tartan
#

ordinals set well-ordered sets modulo order-preserving bijection

wicked ore
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Oh

turbid epoch
sick burrow
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Yeah that's a good way of putting it mniip

turbid epoch
#

I feel intellectually outpaced in this chat.

compact tartan
#

ordinals have more structure as well as a smaller quoetienting relation

wicked ore
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So it’s like an equivalence class of all sets with the same cardinality

sick burrow
#

Though don't you need AC to get a cardinality for every set

compact tartan
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equivalence class

wicked ore
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Ye ye

compact tartan
#

vaguely

sick burrow
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Yeah aren't cardinals well-orderable sets modulo bijection?

compact tartan
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all sets are well-orderable sotrue

sick burrow
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I mean yeah

wicked ore
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So I understand the purpose of cardinals, but why do ordinals exist

compact tartan
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well-orderable != well ordered

sick burrow
compact tartan
sick burrow
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I mean I'm keeping up right now

wicked ore
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Transfinite induction?

compact tartan
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a cardinal number describes how many there is of something, an ordinal number describes when something comes up in "sequence"

sick burrow
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But like half the time this chat talks about serious math it's just gibberish

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Though it's fun to see myself gradually understanding more and more

wicked ore
wicked ore
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Because it’s got the order, right

deep mango
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If you spend a lot of time here you will pick up on what the big words mean until you become another one of us, people who use big words without really knowing what they mean

compact tartan
sick burrow
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That's because he just makes things up

turbid epoch
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I swear when I start learning this stuff, I'm stunting on all of you so hard.

deep mango
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Hmm yes. Etale cohomology. Ah yes, bundle epimorphism.

wicked ore
neat lintel
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how do i do this?

turbid epoch
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Ahhh yes, Aether.

wicked ore
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That’s pretty cool

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Ok, thanks

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Wait one more question

compact tartan
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ordinals are for like, "longer" sequences

sick burrow
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Category theorists just scribble arrows everywhere and call it math

wicked ore
compact tartan
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yeah hence the actual definition is trickier

sick burrow
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Wait can you not have equivalence relations on a class?

wicked ore
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So it gets finicky with the axioms you’re using, I’m guessing

compact tartan
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with choice we can actually provide a "canonical" representative for every cardinality

sick burrow
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I don't see why you couldn't

wicked ore
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Cause set of all sets isn’t a thing, right

compact tartan
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it's too large

sick burrow
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You just define it with formulas rather than a set

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Right you can't actually take modulo on V

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Hence the canonical cardinals

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God I find it so cool that I actually know (basic) set theory now

compact tartan
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one way to do it is take a set X, come up with a well-ordering, which will give you an order-preserving isomorphism with some ordinal alpha, and then in alpha+1 take the least ordinal with the same cardinality as X, which is well-defined because alpha+1 is well-ordered and contains at least alpha

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you can show this is independent of the choice of the well-ordering (and resp. alpha)

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in this definition all cardinals are ordinals, but only very particular ones

sick burrow
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I mean you just take the smallest cardinal with an injection into the set as its cardinality

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*largest

compact tartan
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we're defining what a cardinal is

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that's like very circular

sick burrow
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Cardinals are just ordinals k s.t. alpha<k implies there is no injection from k into alpha

compact tartan
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ok

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that's isomorphic to my definition

sick burrow
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Yeah I just didn't read what you said :chad:

compact tartan
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but also in your definition you can't take the "largest cardinal"

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not well defined

sick burrow
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Just reverse the well ordering sotrue

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Right you just take the smallest cardinal that the set can inject into

compact tartan
#

sure

wicked ore
compact tartan
proper tide
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the real no. number line seems in 1st dimension only back and forth but to reach 4 th dimansion we need a 3d dimesion, my thought

wicked ore
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That definition I pasted doesn’t have modulo

compact tartan
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abstract idea vs concrete implementation

sick burrow
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The way I saw oridnals defined is a transitive set well-ordered by set inclusion

wicked ore
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The modulo is the idea

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But since that’s impossible

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You have to define it kinda carefully

compact tartan
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well

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there's a relation of isomorphism on the category of well orders

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and the von-neumann ordinals (defined in your image) form a skeleton

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meaning there's exactly one von neuman ordinal in each isomorphism class of the category of well orders

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i.e. we can use the class of von neumann ordinals as an "implementation" of V/~

wicked ore
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Ok

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Do the vn ordinals act as a sort of representative for the “equivalence class” or does that not apply here

compact tartan
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exactly

sick burrow
wicked ore
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Ok that sort of makes sense yeah

compact tartan
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no this is cat theory

wicked ore
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Yeah I was gonna ask

compact tartan
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there's a universal property you want to satisfy (quotient)

wicked ore
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Doesn’t this have some things outside ZFC

compact tartan
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and this is an object that satisfies this

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yes, this is outside ZFC

sick burrow
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Isn't everything you do cat theory mniip?

compact tartan
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large categories and all that

compact tartan
sick burrow
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Since you're a cat and you do theory

wicked ore
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Small cats are like, each object is a set right

compact tartan
#

no

wicked ore
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Small cats are also cute

compact tartan
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the collection of objects is small enough to be a set

wicked ore
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Oh ok

compact tartan
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but alas

sick burrow
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What is a universal property mniip

sick burrow
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L

wicked ore
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No way

compact tartan
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could be a slice category of a profunctor

sick burrow
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You say this like you think I have any idea what those words mean

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The extent of my category theory knowledge is the definitions of category and functor

wicked ore
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Lol yeah

wicked ore
sick burrow
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Yes

compact tartan
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in vague terms, we're looking for some object with a certain pattern of arrows, such that for any other object with its own pattern of arrows, there exists a unique "mediating arrow" such that the second pattern factors through that arrow and the first pattern

sick burrow
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Ordinals and cardinals can be formalized within ZFC. If they couldn't, ZFC would be kinda lame

wicked ore
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Sounds like a morphism of morphisms in a sense

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Or like, a morphism between entire categories

compact tartan
#

no

sick burrow
compact tartan
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the "set of all sets" is mostly there for intuition

sick burrow
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mniip how should I learn cat theory

compact tartan
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you can do the rigorous details

sick burrow
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Like how much should I be learning for alg top

compact tartan
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for "normal maths" it's useful to learn at least the "categorical language", i.e. the definitions of initial objects, products, equalizers, pullbacks, their duals; as well as the notion of functoriality and naturality

wicked ore
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Category theory is completely formalized right? Like ZFC?

compact tartan
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uhh

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category theory is more of a vibe in that it extends beyond ZFC

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but if you insist you can formalize category theory inside ZFC

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but there will be caveats

sick burrow
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is Riehl's book good for intro cat theory

compact tartan
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I guess

wicked ore
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Like are categories undefined objects sorta like sets and you define their properties

compact tartan
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you take a universum U and take the category of elements of U

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a category whose set of objects is in U is called U-small

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if C is U-small then [C, C] might not be U-small anymore

wicked ore
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Hold up, what’s a universum, and you said take the category of elements of U

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But what is a category (formally)

compact tartan
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if we're restricting our attention to ZFC, it's a set Ob, together with a family of sets Hom(X, Y) where X, Y range over Ob

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together with a family of elements id_X in Hom(X, X) for every X in Ob, and a family of functions \circ : Hom(Y, Z) x Hom(X, Y) -> Hom(X, Z)

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that satisfy some identity and associativity conditions

wicked ore
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Yep

compact tartan
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the "categorical vibe" implies that Ob doesn't have to be a set and can be something more vague, like a class, or something without a notion of equality at all

vivid halo
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people talking about size issues
ng has joined the chat

compact tartan
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for Hom we actually care about equality

wicked ore
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I love this, categorical vibe

compact tartan
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but it can still happen to be a class

wicked ore
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That’s what I’m asking

vivid halo
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it can be taken to be a proper class

compact tartan
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no that's not what you're asking

wicked ore
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What

compact tartan
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"formally, in ZFC" and "if it's not a set then what is it" are incompatible requirements

vivid halo
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okay yea that too

sick burrow
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wait so like with the cat theory definition of a group

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the morphisms are group elements right?

vivid halo
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in NBG you can talk about classes I guess

wicked ore
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I thought everything was a set in ZFC

compact tartan
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you could be referring to at least 2 different things here

sick burrow
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groupoid with one element

vivid halo
compact tartan
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sure

compact tartan
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but cat theory goes beyond ZFC

wicked ore
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Yes

compact tartan
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ergo when you're asking for a ZFC formalization we're only exploring a part of it

late skiff
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hello people!

sick burrow
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oh right because every group is a subgroup of a symmetric group

wicked ore
compact tartan
#

magic

vivid halo
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so there are a few ways to do this

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NBG is a bad way to do it but it works for really crude purposes

wicked ore
vivid halo
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since NBG gives you a way to talk about sets and proper classes

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so you can talk about the proper class of all sets being the class of objects in the category of sets for instance

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there are some issues with taking this approach in general though, since you can't talk about a "metaclass" of all classes and repeat constructions (e.g. for the Yoneda embedding)

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so you need something more subtle

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the two standard ways to do this are either through ZFC + TG (Tarski-Grothendieck axiom) or ZFC + exists a proper class of inaccessible cardinals

compact tartan
#
  1. ZFC and copium
  2. ZFC+large cardinals as universes
  3. NBG with class of all sets as your universe
  4. Tarski-Grothendieck with as many universes as you want
  5. A ramified type theory
vivid halo
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these are equivalent statements, just depends on whether you like the setup of Grothendieck universes or the setup of inaccessible cardinals

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  1. ZFC and copium
    kek
compact tartan
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  1. vibes and magic
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most normal mathematicians I've seen go for ZFC+TG I think

vivid halo
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yea

compact tartan
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I'm a type theory junkie though

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U_n : U_n+1

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there's your TG

vivid halo
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yea exactly

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either of these approaches is more common among category theorists/type theorists

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though some people still like inaccessibles

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there's also some reasons why the inaccessible approach is a little more expressive but either is fine

compact tartan
#

I still don't understand how hTop is not concrete

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I've read the proof it checks out but like

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how

vivid halo
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oh yea it's a weird proof

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I never understood it

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like it's one of those proofs you can read each line and still not understand what just happened

compact tartan
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ok so like reality check

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if we have an ess. surjective functor between small categories, does it always have a section?

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hmm

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ess. surjective and full

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I guess

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sounds like this should be a form of choice

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which means non-concreteness of hTop is a failure of "large" choice?

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choomers btfo

turbid epoch
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Help, this chat is a fever dream.

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Also, can someone enlighten me about the Axiom of Choice?

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More specifically, what it is and why it amounts to the statement "The cartesian product of a non-empty set is non-empty."

compact tartan
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The Axiom of Choice is obviously true, the well-ordering principle obviously false, and who can tell about Zorn's lemma?

turbid epoch
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Bruh, I'm a lvl 0 goon.

sick kite
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what does it mean for an axiom to be true?

turbid epoch
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Wtf is the axiom of choice, I need information.

compact tartan
#

the formal statement is:
$$\forall A, \varnothing \not\in A \implies \exists F : A \to \bigcup A, \forall X \in A, F(X) \in X$$

fathom swallowBOT
compact tartan
#

this is the "C" part of ZFC

turbid epoch
#

Yeah, more like the Axiom of Incomprehension.

compact tartan
#

you can prefer to include or exclude this axiom from your assumptions

sick kite
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oh its a stackexchange copypasta

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wait nvm

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im so fucking stupid

turbid epoch
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@compact tartan I'm baby, explain it to me like Im 5.

compact tartan
#

I don't think I can

sick kite
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but what if im 10 mniip

compact tartan
#

if you have a bag of bags, and you know none of the bags is empty, sounds like you should be able to pick an item from each bag

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and there's no dispute about this if the number of bags you have is finite

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but turns out it gets complicated in the infinite case

turbid epoch
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But what does this choice of ours have to do with cartesian products?

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wait a minute, I think I just got it.

compact tartan
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functions are related to cartesian products

turbid epoch
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yeah thanks

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although let me be frank @compact tartan

compact tartan
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the AoC is surprising because of the statements that are equivalent to it and statements that follow from it

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existence of non-measurable sets or more famously the banach-tarski paradox is a consequence of AoC

cinder zephyr
#

TFW your prof gives a HW answer in class neko_hype

mint patio
#

partial fraction decomposition is beautiful and useful.

turbid epoch
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Until you have 5 terms in the denominator and have to solve a system of 5 equations.

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Yikes.

bronze pelican
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new veritasium math video

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will this break math discord 😬

sick kite
#

this is just math history

turbid epoch
#

Yeah, it's just the history of i.

bronze pelican
#

good

turbid epoch
#

And depressed cubes and the cubic formula.

bronze pelican
#

there cant be any posssible way for cranks to misinterpret that right ?

sick kite
#

surely

bronze pelican
#

right? monkagigagun

turbid epoch
#

cranks?

compact tartan
bronze pelican
#

amazing emote

deep mango
sick kite
#

😬

turbid epoch
#

yeah, but what does crank refer to?

deep mango
#

New veritasium just dropped sotrue

bronze pelican
#

crank is someone who is delusional in their claims about math

compact tartan
#

is this a video about cubics and complex numbers?

sick kite
#

yes

compact tartan
#

(I haven't watched it)

turbid epoch
#

yeh

sick kite
#

math history of i

compact tartan
#

"led to quantum physics"

sick kite
#

mostly talks about 16th century italians

compact tartan
#

bold claim

deep mango
#

Wow... The cubic equation... Has square roots of negative numbers??? Wtf???

compact tartan
#

I'm sure physicists would have invented complex numbers if they needed to

sick kite
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not only is it bold, it is unsubstantiated

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all it says is

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"oh look multiplication by i is like rotation"

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therefore physics

bronze pelican
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that's also the basis of conformal geometry

compact tartan
#

"it's like a number but if you square it you get -1" - shit physicists say all the time

velvet dagger
turbid epoch
#

I think this is build up to another video.

turbid epoch
#

idk, just a feeling.

sick kite
#

the same happened yesterday aha

pale orchid
#

prepare for "there is a hole at the base of physics"

crystal stone
#

Huh

compact tartan
#

mathematicians beat them to it

crystal stone
#

#excuses

sick kite
#

mathematicians in shambles

bronze pelican
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complex geometry is the most based thing #Riemann #Poincare

velvet dagger
turbid epoch
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Mathematicians make math, physicists find uses for it a hundred years later.

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All is as it should be.

crystal stone
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Eh

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I dunno

bronze pelican
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We need a Poincare fan club

crystal stone
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Witten is better than most mathematicians

compact tartan
deep mango
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What if what?

compact tartan
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sometimes it's as simple as "wait this is just group theory"

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sometimes it's an open problem for 50 years

deep mango
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I know what if. You don't need to say it.
pandaScreams

crystal stone
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Dirac did some crazy stuff

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I'm still skeptical about dirac's delta function

bronze pelican
#

Poicare is really my hero

crystal stone
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I have a suspicion that Green beat him to it

velvet dagger
#

All math is but a prelude to p-adic hodge theory

bronze pelican
#

and Jacobi

compact tartan
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"it's like a smooth function but it's zero everywhere except origin"

bronze pelican
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and Abel

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and Riemann

turbid epoch
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It's integral is 1.

crystal stone
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I think Green really beat him to it

sick kite
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  • c (probably)
crystal stone
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But I don't know enough about history and haven't read Green's original paper where he came up with his functions

compact tartan
crystal stone
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Well

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Hey, beating someone to it 100 years early

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Is a big deal

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I'd have to sit down and sort through it

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I dunno if I have the patience for that though

pale orchid
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moonbears like

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"ah, yes, c1 + c2"

compact tartan
#

how do you rationalize learning math history if there's so much interesting math to learn instead

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couldn't care less who invented it and when

crystal stone
#

I like the development of ideas

turbid epoch
#

Why do people write QED at the end of every proof? What does Quantum ElectroDynamics have to do with anything?

bronze pelican
crystal stone
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I enjoy history and I enjoy math

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and I enjoy settling misconceptions about history of math

bronze pelican
#

you see math is not just abstract ideas that exists with out human input. Every definition you use has a historical context

turbid epoch
#

Some math stories are amazing.

compact tartan
#

I mean

crystal stone
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le meme dies in duel lmao haha dude you could imagine just dude

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genius

compact tartan
#

that sounds like applications

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yes you can apply math to other things

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but why do I care who did it though?

turbid epoch
#

Like when they gutted a ####ing guy because he drew the square root of 2 outside Pythagoras' house.

bronze pelican
#

what do you mean applications

compact tartan
#

applicataions and or motivation

bronze pelican
#

I find learning about the history of math and mathematical ideas very rewarding

crystal stone
#

I guess in the longer term I think I'm more interested in curriculum, education, and development of ideas

compact tartan
#

in my mind those things are not related to specific persons at all

crystal stone
#

Rather than doing pure math research for the rest of my life

#

but we'll see how gripping I find more research

#

It is interesting and I do like solving problems

bronze pelican
#

its very interesting to see the historical development of ideas

#

it gives you a newfound respect from people like Riemann

crystal stone
#

I guess the research I'd do is interesting

#

but I don't jump for joy over it

velvet dagger
#

I find history of math to be cool more from a history pov than a math pov

crystal stone
#

I disagree

#

You don't find it interesting from that point of view

velvet dagger
#

Ballsy claim

#

What's your alternative suggestion?

crystal stone
#

You find history of math to be cool from a math point of view

#

and you think the historians are full of shit

#

So the history point of view is bad

#

According to you, of course.

velvet dagger
#

Lolol

sick kite
#

Dami, you DO NOT THINK WHAT YOU THINK

compact tartan
#

math history from the history point of view catThin4K
math history in the 1940s nyandark

crystal stone
#

Teichmuller reax only

turbid epoch
#

Are there any new fields in math that have just emerged in the past decade or so?

compact tartan
#

homotopy type theory came about in 2013 ish

turbid epoch
#

just the one?

crystal stone
#

What do you mean by "field"

compact tartan
#

probably plenty of others

velvet dagger
#

But yeah I guess my thing with math history is, it's cool for general stories/it's cool to sometimes contrast how we think about things today vs how less enlightened people from 1700s/1800s thought about stuff

turbid epoch
#

I guess, field to me means that it is, to a degree, separate from other math?

crystal stone
#

"separate from other math"

#

Ain't gonna happen buddy

compact tartan
#

how old is condensed mathematics?

turbid epoch
#

That's why I added "to a degree"

compact tartan
#

3 years?

crystal stone
#

what is condesned math

compact tartan
#

I have no idea

crystal stone
#

oh it's that shitsee guy

compact tartan
#

yet another "the most ambitious crossover in the history of math"

velvet dagger
#

But I think it doesn't often inform how I look at current math, and generically I just prefer modern arts

turbid epoch
#

Condensed mathematics is the (potential) unification of various mathematical subfields, including topology, geometry, and number theory. Ripped from Wiki.

velvet dagger
#

Oh yeah condensed math is some new age stuff

#

But yeah I'll just say don't expect entirely new fields of math to pop up that frequently

compact tartan
#

shit like this is good leverage for constructivist propaganda

#

I should be all over this

#

but no time

#

still stuck on HoTT memes opencry

velvet dagger
#

Since it turns out a lot of stuff is done by more incremental work or adapting existing math, which turns out to be still be very robust

turbid epoch
#

idk this is some fields medalist guy saying this. Is this truly bs?

compact tartan
#

no one said it's bs

velvet dagger
#

Condensed math?

crystal stone
#

It's done by shitzee

#

So it's probably abstract nonsense

velvet dagger
#

Yeah nobody thinks it's Bs. I don't yet know what exactly it does but

crystal stone
#

I have to take an algebra qual sloth

#

That includes sylow and galois

turbid epoch
crystal stone
#

I'll be face to face with the enemy

crystal stone
sick kite
#

'accent'

velvet dagger
#

Scholze's passive observations probably destroy my entire math career lol

surreal sapphire
crystal stone
#

I watched one video by laurie or lurie

#

and they got the fourier transform definition wrong

#

and I stopped watching

surreal sapphire
#

his camera is super annoying though

#

it keeps trying to focus

velvet dagger
#

Also I'm p sure you mean the categorification one lol

crystal stone
#

they missed a negative on the fourier transform

#

Yeah

#

I was like I'm out

velvet dagger
#

Oh that's an alternative convention lol

crystal stone
#

Nope

#

Why

#

I don't wanna know why

#

All I know

#

Is no

velvet dagger
#

I'm not sure why but I remember that conventions disagree

#

So he's not quite wrong here lol

crystal stone
#

It's non-canon

compact tartan
#

how many of 2pi do you write in your forward and backward fourier transform

crystal stone
#

It ain't a part of my gospel

velvet dagger
#

Whatever makes the stuff unitary

crystal stone
#

I got a chuckle out of that

velvet dagger
#

So iirc 1/sqrt(2π)

compact tartan
#

understandable

#

in CS it's common to use non-unitary fourier transforms

#

no factor on the forward

crystal stone
#

Yeah who would ever study

#

Fourier transforms of boolean functions

compact tartan
#

excuse me it's called Z_2

crystal stone
#

{-1,1}^n

#

Deal

velvet dagger
#

2-adics?

crystal stone
#

W/f

#

it

compact tartan
#

dyadic integers catThin4K

crystal stone
#

I can't believe I'm gonna have to learn all that shit

pale orchid
#

to be fair, a sequence of alternating -1s and 1s is and transforms into useful stuff

crystal stone
#

And what I will probably do

compact tartan
#

does there exist a hadamard matrix of order 668

#

tell me, signals guy

pale orchid
#

let me google hadamard matrix

#

yeah sure

#

they use that sort of stuff for coded excitation with large arrays

compact tartan
#

it's the shit that most spread spectrum transmission formats use

pale orchid
#

sounds about right

#

(pseudo) orthogonal sequences make nice coded signals

#

both from the spectrum/interference standpoint and from the SNR standpoint

#

"sIgNaL ComPrESsIoN"

crystal stone
#

Do you work as a signal processing engineer

#

or do you just study signals

compact tartan
#

I think his undergrad was in antennas or something

pale orchid
#

lmao

#

it wasn't

#

and both, technically

neat lintel
#

antenna engineering thinkies

pale orchid
#

since i'm hired both at the uni and at a company that collabs with it

crystal stone
#

Oh nice

#

Signal processing is like my back up plan

#

I almost got a job as an RF engineer

#

but they found out I didn't wanna live in sacramento

#

So then I didn't get the offer

#

e.g. I would've worked for like 1.5 years

#

and then asked for a transfer

cold needle
#

hadamard matrices catThink my algebra prof might give a talk on it next semestr

bronze pelican
#

I feel like the part about shrodinger's equation was unnecessary in the veritasium video

#

He could've just left it at the history of the cubic equation

#

I don't think the discussion about the shrodinger equation actually added anything of substance

sick burrow
#

what does orientation look like on an 3-simplex

crystal stone
#

I liked his explanation of the cubic formula

bronze pelican
#

Yeah

crystal stone
#

I've heard the story so many times, it's one of my favorites in math

bronze pelican
#

It is good

crystal stone
#

Cardano, Tartaglia

bronze pelican
#

And deserved to be on YouTube

crystal stone
#

I think it's way better than "Galois in a duel" meme

bronze pelican
#

They're both memes

crystal stone
#

I dunno

#

That's a meme

bronze pelican
#

What really needs to be showcased

#

To a wide audience

#

Is Poincare and Klein's race to prove the Uniformization theorem in complex geometry

#

Now thats an exciting story

#

And I don't know the full story

#

But I wish I did

crystal stone
#

Oh hey fourier was the first to speculate that the Earth's atmosphere traps heat coming from solar radiation

#

That's pretty neat

#

Well at least first to speculate it in a real, academic sense with mathematicalisms at the foundation

#

It's fun to read old books on science

#

"Scientists speculate there could be other galaxies"

neat lintel
#

Am I the only one who thinks that Nasa does fake shit?

#

Look at how these nuts are fliying, it looks so fake.

#

The lighting of them looks like the CGI of a highschool project.

leaden torrent
#

nasa
canadian space agency

neat lintel
leaden torrent
#

anyway, looks fine to me

#

im sure the video is touched up (obviously, the label is blurred)

#

but that would be very impressive cgi considering the reflections on the aluminium foil

neat lintel
#

The way it is fliying looks so fake, as if they were putting a 2d clip on a 3d.

leaden torrent
#

...i dont see it

neat lintel
#

They even admited to me that it was made the same way Star Trek was.

leaden torrent
#

thats... a different video

#

are you just trying to spread conspiratorial bs in a random big server

#

screw off

neat lintel
#

Nah, bro I am actually triying to discuss it with people.

#

Cause if it is really all fake I would be sad.

wild lantern
#

What else is there to discuss other than that it looks fake to you?

leaden torrent
#

not sure that bringing up a comment from a totally unrelated video is a good faith discussion

#

you havent tried to explain why it seems fake other than "it looks 2d", but it doesnt look 2d to me

#

and the reflections on the foil and the can make the depth fairly clear

#

at least the people who find reptilians in video compression artifacts have an image they can point to

wild lantern
#

Nasa's videos look fake: broke Space is fake: woke

#

Jk

leaden torrent
#

nah space is real, NASA is fake

wild lantern
#

Lol

leaden torrent
#

NASA is a big money laundering scheme

#

they say every space shuttle launch costed billions

#

where did that billions come from, huh?

#

clearly illegal black market activity

sick kite
#

pablo escobar didn't die and is just head of money laundering space agency

#

faked his death

leaden torrent
#

actually space stuff would probably be a surprisingly effective way to launder money rn lmao

#

eh i guess its too public facing/sensationalized

#

but like

#

no one knows how much shit should cost

wild lantern
#

I would support a nasa money laundring scheme if it somehow managed to further space travel and junk.

leaden torrent
#

if spacex says a rocket costs $800 million

#

who are we to argue

#

maybe its only $400 million

#

meanwhile, if you claim that car wash costed $60, im gonna get suspicious

wild lantern
#

Markup for government purchases is pretty crazy in general.

#

Seems plausible for space stuff too

sick kite
leaden torrent
#

reporting income tax on your car wash

sales: 7
total earnings: $522 000

sick kite
#

who's saying I'm reporting income tax?

neat lintel
#

I actually really hope that stuff is real.

#

Cause espacilly stuff like LISA is big shit (Even though that's from ESA)

leaden torrent
#

why focus on such out there conspiracy theories instead of ones that actually make sense for the government to pursue

#

like mass selling stocks in early march 2020

eager reef
sage stag
#

What shape is this lol

leaden torrent
#

what shape is what

sage stag
#

these beads

#

like two cones

leaden torrent
#

the object itself is an abacus

sage stag
#

I get that but the shape it is used, I know there is a name just cant remember?

leaden torrent
#

dicones?

sage stag
#

yes but inverted

leaden torrent
#

(dicone is a synonym)

sage stag
#

I see

leaden torrent
#

but tbh id call those closer to "saucer shape"

neat lintel
#

Anyone actually able to quote stuff like like EGA or Harthshorne. Looked up books saying intro to AG and a lot of people mentioned it, reddit called finishing them a rite of passage. Im doubtful becsuse both look long and tedious to go through in full.

leaden torrent
#

i read hartshorne in undergrad

#

i would not recommend it

#

ega is pedagogically terrible and only really valuable as a reference

#

hartshorne is fine but not great

bronze pelican
#

I feel like I'm ready for Hartshorne

#

Now that I've done some complex geometry hyperhonk

neat lintel
#

oof

light needle
#

based yamin

#

yeah like, i read ch1 so far, and all of it feels like a continuition of complex geo

#

I should get back to hartshorne soon catThin4K

hollow ginkgo
jovial ember
#

Do you also enjoy dragging ur balls through broken glass?

cold needle
#

huh

frozen venture
#

Are there professors in this discord?

neat lintel
#

every professor is busy, every professor is in every uni

frozen venture
#

I'm wondering who all the smart yellow namers are

#

are you guys grad students? advanced undergrads?

jovial ember
#

We are legion

#

ReLisrixallt we are all different ages lol

#

There’s hsers, undergrads, grad students. There is one professor

#

He’s also a cat

#

Actually maybe two now that buncho graduated

#

And there’s zeta

#

Lol

neat lintel
cold needle
#

i am a second year undergraduate

frozen venture
#

So how does one achieve the coveted yellow name?

cold needle
#

unknown

#

you must be a good role model and accepted in the community or something

#

idk

#

i should know

jovial ember
#

Be friends with the other ones

#

Idfk

toxic schooner
#

chmonkey will u be my friend

jovial ember
#

No

toxic schooner
jovial ember
#

Chmonkey is everyone’s friend

#

Except yours

toxic schooner
#

why sad_think

jovial ember
#

😨

#

Cuz ur my buddy

toxic schooner
jovial ember
#

Can’t believe my buddy hasn’t wished me happy bday

neat lintel
#

happy belated birthday

jovial ember
#

It’s still today

#

:3

#

Where I live

neat lintel
#

tomorrow's my birthday

toxic schooner
#

its your birthday!?

jovial ember
#

Oh yes I remember

toxic schooner
#

Happy birthday!

jovial ember
#

I’m 2 days older than you

neat lintel
#

😊

toxic schooner
jovial ember
#

Also I forget did u used to have like

neat lintel
#

happy birthday

jovial ember
#

Jantheman

#

As ur name

#

Or was that some1 else

#

Or Jan something

neat lintel
#

janman

jovial ember
#

Oh okay

#

Cool cool

#

I wasn’t sure if that was u

#

Or not

toxic schooner
#

🐒

#

🪑

#

chmonkey in a nutshell^

jovial ember
#

I think I remember that the bios were the same or something

#

But I guess ppl didn’t read ur bio

#

Hence the new name

#

Actually

#

👑
chmonkey

#

Me in a nutshell

toxic schooner
#

ofc

#

👑

#

🐒

#

🪑

jovial ember
#

Chmonkey

#

Lmaooooooo

neat lintel
#

lmfao

#

dalgona with mandelbrot on it

jovial ember
#

Follow up btw

neat lintel
#

oof

pale orchid
#

wait, read my about me is janman?

#

wtf

#

i see a random person with generic roles and a generic nickname lol

neat lintel
#

or either nJanmoid

pale orchid
#

i thought it was someone new

fast ivy
#

Fuks sully

jovial ember
#

Fuks

wicked ore
#

Maybe this is a dumb question but can you have a sequence of functions (f, f’, f’’, …), where f’ means derivative? Can such a sequence “converge”?

#

I’m thinking about how polynomials “converge” to zero, some functions “converge” to e^x, and some functions diverge

devout nacelle
#

Polynomials converging to 0 catthonk

#

But I think you can certainly have the sequence of derivatives

#

Provided f is infinitely differentiable of course

wicked ore
#

Yeah

devout nacelle
#

And it's meaningful to interpret its convergence as any other sequence of functions

wicked ore
#

Any other sequence of functions? How do those work?

devout nacelle
#

The one I'm familiar with is pointwise convergence

#

F_n converges to f if for any x in the domain of f and any e>0, there exists some n such that |F_m(x)-f(x)|<e for all m>n

#

Basically just the usual convergence but for images of your functions

last oxide
#

it depends on the norm you choose

devout nacelle
#

I'm just assuming R here

#

With the usual norm

last oxide
#

you are doing pointwise, ye

#

but the usual norm is sup

devout nacelle
#

Ah okay

last oxide
#

for some suitable sense of usual smugpepe

devout nacelle
#

sup|F_m(x)-f(x)|->0 as m->\infty?

wicked ore
devout nacelle
#

x ranging over the domain

last oxide
#

the for any x quantifier goes after the property

wicked ore
last oxide
#

if you want sup norm

#

but ye

#

thats the same

rocky mulch
#

hey guys, i'm currently in grade 12 and working on a math investigation (for those of you who know what the IB is, i'm working on my math IA) and was planning to do an engineering optimization problem, do you think it's a good idea to do something simple like the most efficient rocket launch trajectory, my requisites are it can't have complicated physics but the mathematics have to be like simple calculus(as a reference it's my first time studying calc but i could learn a bit of more sophisticated calc if neccesary)

gloomy marten
#

most efficient rocket launch trajectory
Requisits can't have complicated physics

#

I'm guessing air resistance is negligible

pale orchid
#

you can do a much more simplified version of that problem

#

if you throw an object with, say, a catapult, at which angle should it leave the ground so that it reaches the largest horizontal distance possible?

gloomy marten
#

Oh you mean that?

#

That's rather easy

#

If there are no walls and air resistance is negligible, just calculate de derivative

#

I made an animation of that for physics in my senior year

pale orchid
#

(that's just my suggestion, cuz the other problem they gave is out of their reach)

#

but yeah, it's like beginner level physics and you can use calc to optimize it, so

gloomy marten
#

@pale orchid I think you learn about Kepler's laws in 12th grade, so it might be possible to solve using elementary physics and some calculus, the best trajectory for a rocket. Assuming boundary restrictions on the gravitational pull of a planet

pale orchid
#

knock yourself out then

gloomy marten
#

I mean they said it was an investigation thing

#

the most efficient rocket launch trajetory is also a weird question, what type of optimizations are you looking for

#

least fuel consumption is probably like close to enough for escape velocity, and just use planets as catapults

inner finch
#

solve triple body problem

rocky mulch
#

@gloomy marten @pale orchid I've just read your discussion and i think I'm gonna use the catapult idea considering air resistance and that i think I should get the difficulty required, thanks for your help :D

gloomy marten
#

gaming

turbid epoch
#

Is this actually valid? lol

toxic schooner
# turbid epoch

but 2^(1/2) is also irrational,
is the theorem trying to say otherwise thonkstein

gloomy marten
#

the proof by fermat's last theorem is simply not valid for n = 2

toxic schooner
#

yes, its not, ik

turbid epoch
#

but is this proof actually valid tho?

toxic schooner
#

aahh
ig maybe? i mean its a theorem proven to be true, so i dont see a problem

gloomy marten
#

the normal proof is really simple though

turbid epoch
#

Some people were saying "circularity" something something but I see no way the usage of this is circular.

toxic schooner
gloomy marten
#

it might be, I don't know the proof for fermat's last theorem

toxic schooner
#

how is this circular?

gloomy marten
#

anyway

#

if 2^(1/n) is rational, exists p,q coprime such that it is equal to p/q.
2q^n = p^n => 2|p => (by sub) 2|q. contradiction (for n > 1) qed

turbid epoch
#

It's a basic 10th grade proof.

#

yeh

pulsar ruin
#

fun

inner finch
toxic schooner
#

oh

neat lintel
#

Or you can just stop before last line and say a^n is even and b^n even which is contradiction

#

a^n even because divisible by 2, b^n even because n>=2 on both sides implies such.

nimble shuttle
#

andrew wiles is most famous for his proof of the modularity conjecture, which finally resolved the famous, long-standing problem of whether the cube root of 2 is rational

inner finch
#

lmao

steep mountain
#

too bad it cant prove square root of 2 is irrational

turbid epoch
#

We need a stronger version of Fermat's Last Theorem for such sorcery.

neat lintel
#

Is it possible to write like this? r ∧ n ∈ ℕ, x ∈ R?

pale orchid
#

you just did

#

what do you want ^ to represent tho

neat lintel
#

That r and n are natural and x is a positive real number

pale orchid
#

you can just use a comma

neat lintel
#

Where?

pale orchid
#

$r,n \in \mathbb{N}, ,, x \in \mathbb{R}$

fathom swallowBOT
neat lintel
#

Ohh thanks!

#

Just another quick question

#

If I have a three statements equation

#

Where do I say this about r,n and x?

pale orchid
#

wdym

#

write it out in words

neat lintel
#

So I have an equation with three statements. I want to say that r,n is natural and x is a positive real for every three statements

#

I've never done this before

#

Right now it looks like this

#

And I don't know if it's right

pale orchid
#

idk why there are ifs

neat lintel
pale orchid
#

but you can just separate the stuff with commas as you did

neat lintel
#

There are three different equations

pale orchid
#

for example

#

and you can separate the conditions with commas

#

but honestly you should just describe r,n, and x BEFORE you define P

#

cuz you're writing the same thing over and over

neat lintel
#

yeah I was wondering that. How do I do that? just put it infront of P in brackets?

#

like this

pale orchid
#

you can write it above and use words

#

nothing wrong with words

#

given r,n \in \mathbb{R}, etc,. the function P is defined as

neat lintel
#

Thank you so much!!!

#

I'm in my second year in highschool so you can image that this is WAY a head of my knowledge

#

Or thrid maybe if you translate it from I live.

#

This all started with 3b1b video, and then I got obsessed

pale orchid
#

that's aight

#

there's no need to use symbols for everything, especially if it makes things more difficult

neat lintel
#

Yeah but if I don't state that I will get like 100 solutions.

pale orchid
#

what i mean is you can use words and that doesn't make it any less correct

neat lintel
#

Riight

#

But this kind of looks cooler. Like if I show it to my teacher

#

But she won't really care

pale orchid
#

e.g. "consider the numbers $n,r \in \mathbb{N}$, $x \in \mathbb{R}$. We define the function $P: \mathbb{N} \times \mathbb{N} \times \mathbb{R} \to \text{(idk what your codomain is)}$ as:
$$P = 0$$

fathom swallowBOT
pale orchid
#

just as an example lol

neat lintel
#

Riiight

#

It's kind of hard to understant the P: N x N x R ->, part

#

never done that lol

sick burrow
#

It's just a function that takes ordered pairs of natural numbers as input

gloomy marten
sick burrow
#

Wait NxNxR so I guess ordered pairs of natural numbers and one real number as input

gloomy marten
#

\,,?

pale orchid
#

\,\,

gloomy marten
#

I see

#

thanks

sick burrow
#

So ordered triples where the first two entries are natural numbers and the last is any real number

neat lintel
#

@pale orchid sorry if this is bothering lol. Did I do it right now?

#

n and r are both known values

#

we want to solve for x

#

I should write that P is also known

pale orchid
#

sure i guess

neat lintel
#

So maybe it's less than a function and more than an equation???

pale orchid
#

i mean, you have a binary relation that gives one output in R+ to any input in N x N x R+, so

#

i guess what i would change is that i'd write P(n, r, x) instead of P

neat lintel
#

yeah I didn't really know what that part meant. P could be anything but I always say that P is equal to erf/sqrt(2)

#

Or P could be anything between 0 and 1

pale orchid
#

i dont understand what you mean

neat lintel
#

P is what the range of the probability density should be.

#

so (r+1)/(n+2) -+ x give the range. And the area under that range times (n+3) should equal P

pale orchid
#

idk what you mean by range here

neat lintel
#

So I am calculating probabilities of probabilities

pale orchid
#

the range is a set

neat lintel
#

Oh

pale orchid
#

(and the word is also ambiguous)

#

when you say range, it's all the possible outputs

neat lintel
#

Right so between two values then?

#

Is better to say

pale orchid
#

i assume you mean to fix a value of n and r, and then vary x

#

to yield a curve P(x) for a fixed n and r

#

and then varying n and r yields a family of functions

#

and the definite (probably improper) integral of P(x) yields the probability of x being within some range of values

neat lintel
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Yes. I believe so(?)

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Like lets say for instance a factory produces 100 cars where 2 cars have defects. What is their true success?

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In %

pale orchid
#

sounds like a probability distribution that already exists and you should google how to write properly 😛

neat lintel
#

Have not found anything.

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I used laplace rule of succession

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Because I want to find the two values that are most likely is the car producers succession

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I would love to find a formula for it, that isn't this complicated and hard to calculate as mine is.

pale orchid
#

i would really suggest asking in one of the questions channels tbh

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and regarding notation, a quick read on what functions are and their notation on wikipedia should kickstart you

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for specifics on latex, the latex help channel

neat lintel
#

Thanks!

mint patio
#

yooooooooooooooooo

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im actually enjoying doing engineering for once

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analyzing trusses is so fun

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it's like solving a puzzle

pale orchid
#

sounds kinda truss

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what's a truss btw?

sick kite
pale orchid
#

trussy baka

steep mountain
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kinda truss

sick kite
#

truss 🥴

mint patio
#

hey edd

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im analyzing dnusses now

pale orchid
#

stun seed analysis

sick kite
#

dnussy baka

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🥴

mint patio
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edd don't you want to know what dnusses are : (

steep mountain
#

dnusses deez nutz idk

mint patio
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thanks for ruining my joke james

pale orchid
#

that i answered you with stun seed analysis should've been clear enough

mint patio
#

I don't get it

pale orchid
#

the fundamental theorem of stun seed analysis goes as follows: "read it backwards"

pale orchid
#

😌

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got'em

sick kite
mint patio
#

I've lost all respect for you Edd

sick burrow
#

anyone know anything about the Churchill scholarship?

bronze pelican
#

yes

sick burrow
#

what

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what do you know nYaminoid

sick kite
#

what do you know nYaminoid

sick burrow
#

why bully @sick kite

sick kite
sick burrow
#

@bronze pelican

bronze pelican
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I applied to it

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i didnt get it tho

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o fuq the deadline was yesterday

sick burrow
#

I was just curious because a research program in math straight out of undergrad seems strange

bronze pelican
#

its sort of like a masters actually

sick burrow
#

is it not a research thing?

bronze pelican
#

no, you take courses

sick burrow
#

yeah I read through that

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sounds like you get material vomited at you and then kinda die

sick burrow
#

but then if you survive you might actually learn some math

bronze pelican
#

look at how many number theory courses they have

sick kite
#

too many

bronze pelican
#

I wish i had that at my school 😔