That reminds me of one time back in Texas

I was like, 10, and my best friend was about 6

I bought a new Mac not long ago for something like $1200.

I had friends from school but my parents were a bit more... tight, if that makes sense, worried that friends from school would be bad influences, so I didn't get to spend much time outside of recess. Most of my contact with other kids was their friends' kids, and just my luck, I was the oldest, so most of the time my interaction with them was more of a bitter babysitter than a friend

This was a kid I actually got along with but his sister was so annoying

I can see you doing bitter quite well.

So after reading this one book called "Diary of a Wimpy Kid", I got the idea to try to sell her, went to him, he agreed

So when our parents brought us to the mosque we went around trying to be like "Hey do you want a new sister? We can sell ours to you for $2"

You were a born memer

(We charged that so we could split it $1/person and get ice cream)

Haha!

You're a born entrepreneur.

Somehow, this sounds like a very Indian thing to do. Nothing racist intended :P

lmao

I'm just thinking of Indians I know.

Nobody took it, we decided okay screw the ice cream, we'll knock it down to 75 cents

That didn't work, we were like okay just take her for free

LOL ... and that didn't work either

Somehow, someway, even that didn't work, we were ready to give up

I approve of the India comment

lmao!

Until I got an idea, asked my dad for a quarter, and offered people a quarter to take her

LMAO

@Daminark you shouldn't work as a human trafficker. that's not how you make profit

Demonark doesn't seem to have the notion of profit with the correct orientation.

I think my then self felt that getting rid of her was enough profit

Well, getting rid of an annoying sister vs losing a quarter is a good tradeoff tbh

I had a good relation with my sister

I have a good relationship with my (8 yr younger) sister too, although there may have been a time in her youth when she wanted to get rid of me.

It's worth noting that somehow I convinced the sister as well that this was a good idea

lmao

So she was actually walking around with us

I don't remember what I said

You got a specific story @Ted? :P

what a legend

She probably wasn't fond of you or her brother.

No, I was just the obnoxious overachieving older brother she had to live up to in school.

@Daminark I know some families in Sicily who would reward you for talents handsomely.

A few days later a few people my mom knew from the mosque were talking to her and they said "Oh yeah, my husband told me your son and [DATA EXPUNGED] were going around trying to sell [REDACTED] at the mosque a few days ago, they were so cute"

Hmm, Demonark playing the Godfather. :P

LOL @"so cute"

My parents were immediately like, nope nope nope

I mean everyone thought it was hilarious

But also my parents knew that I was dead serious, if someone said yes we would've handed her off and gotten ice cream

Lol I should really go to bed but this is too interesting

human trafficking is really cute apparently

LOL @philmcole

I don't remember this event directly but my mom tells this to everyone

Funny how none of us is cute in adulthood.

I made coffee so that I could enjoy this more!

ROFL

I'm having a gin martini, personally.

@Daminark "And here is my son [name] which tried to sell his sister on the street" - "Great to meet you!" disturbed look on their faces

I do remember reading this in Diary of a Wimpy Kid and thinking it was a really good idea, I'm somewhat surprised that I was willing to pull it off though

no, Demonark was selling his friend's sister.

okay even better

I'm not surprised, Demonark. Even in your older age you're brazen.

I saw some twins in the toddler age, and the boy had a shirt with "Trading sister for fire truck" and the girl had a shirt with "Trading brother for pony"

looool

Am I? Hmm

I'm surprised they didn't force you to child therapy!

LOL, that's good, @Mathein.

Lol, I mean people at the mosque all thought it was a joke, I think everyone was just too amused by the pricing to get annoyed though

Also people generally knew me as the well-behaved kid so I sorta got this annual shenanigan pass as long as it wasn't too bad

That's why I get suspicious when a kid is too well-behaved. I know they are up to something deep and disturbing!

Have you ever seen a movie called Joshua? @Daminark

Especially Demonark.

NOpe

I don't have sisters but I have cousins and they used to be in general very annoyed with me. I was an obnoxious kid until like five or six years ago. (After which I still am, but in a self-conscious way :P)

Yeah, Balarka, you were definitely more obnoxious in your younger years ...

Hi, can anyone help me? I need to prove the Fourier time shift property, such that: Fourier(x(t-T)) = X(w)*exp(-jwT). Can anyone give me any tips without telling me exactly what to do?

lol you'd know

@Ted All I do now is make puns, I'm far more mild than most

I may have been a bit of a smart ass as a child. One time when my grandpa saw me after some time he said "Look, how you have grown!" (that's something you say to childs when you see them after some time here, idk) and my response was "Yeah, that's irrelevant. More importantly, I have become smart."

Hi @Alex!

Hey @BalarkaSen how are you?

Hey @Alex, what's up?

@Mathein oof

@MatheinBoulomenon Yeah... I used to make cringe remarks like that.

That sounds like you, @Mathein.

Not much @Daminark just low motivation for some reason, I've come to find motivation here

Which is a questionable strat

Indeed

Beyond questionable.

This is a black hole of productivity

you can come here to lose motivation

I guess you can read my story above and maybe the possibility of your adviser selling you will be motivation?

You know, one turns up here, reads about peoples plan to read cohomology of groups, and then my motivation increases

And then no-one actually reads it, but all is well

Lol rip that plan

There's been no mathematics here in ... ages.

hi chat

yeah rip

riup

Hi, can anyone help me? I need to prove the Fourier time shift property, such that: Fourier(x(t-T)) = X(w)*exp(-jwT). Can anyone give me any tips without telling me exactly what to do?

We've heard about Demonark's hooligan younger years.

hi Eric

Oh, right, Lewis asked a question.

@Daminark is still a hooligan

I know the Fourier integral but not sure how to proceed

Make a change of variables in the integral, Lewis?

@EricSilva :O

@Alex I have plans to read obstruction theory, if that helps

@TedShifrin Ohhh that might work, let me try it. :)

@BalarkaSen Characteristic class style?

Ted suggested something along those lines

@Daminark rekt

I'm doing something more hands on, classical.

Cellular stuff

I'd definitely like to read about SW classes again, now that I know some more math :P

Me too

No, Ted suggested you could interpret characteristic classes in terms of that when you learn it.

You wanna do that togather?

@TedShifrin Ah, fair enough.

Sure, did you have a book in mind?

I have M&S

I hate that book

:)

rip

It puts me to sleep

But the cover, it's such a nice orange

If I had to guess I'd say Stasheff wrote that book

Jasper would appreciate it :P

not Milnor

I think you should be sure to look at Steenrod's Fiber Bundles and Mike's suggestion of Mosher-Tangora is good for Postnikov, SW, etc.

Yeah I'm reading Mosher-Tangora for obstruction theory

Steenrods book looks excellent

Ah, cool. Steenrod's book is wonderful.

wishes he hadn't got rid of so many books

I'm up for that

Got rid of them?

oh right, you gave them all up

Gave them all away :S

I remember you saying you weren't going to do math anymore at all :P

Amazing you guys talk about maths books as if they are novels!

They're more like spell books I guess

A really good math book is.

One learns to cast spells from the tomes

@Alex: I'm not doing much :P

@Symposium I'm forgetting the name of that iconic painting that's on your profile picture.

We need to make chat great again maybe

Make Mathematics Great Again

star if you approve

nothing but swamps here

what's the opposite of starring

LOL

flagging

oh no....

Flag if you disagree

@admins

no i want my disapproval to be displayed for all to see

I read a group cohomology thing years ago

did all the proofs

Okay I've acquired steenrods book

never understood anything

rip

"yep okay, that works, yep yep hmm that's right but hmm how do i actually do anything with it ???"

I reproved that group cohomology is $H_*(BG)$ a few days ago

@BalarkaSen Wanderer above the sea of fog.

Yeah I've been trying to fix the bad habit of following all of the text, without finding plenty of examples to test intuition on

Friedrich

Cool fact: If you have a $G$-chain complex, tensoring it by $\otimes_{\Bbb ZG} \Bbb Z$ is equivalent to quotienting it by the $G$-action

I never knew this before

@Symposium Ahh yes

@BalarkaSen It conveys the feeling you get when you realise how mind-bogglingly huge every sub-branch of modern mathematics is.

It's a very mesmerizing experience

to tread through math in general

What field of math would you say Steenrods text belongs to, loosely

fIbEr bUnDleS

I dunno, algebraic topology?

Topology.

I wasn't sure if I could loosely place it in AT or DT

@Alex: You have to read actively, with pencil and paper, and definitely explore everything with examples/counterexamples.

@TedShifrin I proved it, cheers :) the substation was u = t - T

*substitution

That sounds right, @Lewis.

@TedShifrin I've always read math actively, just not sufficiently so it seemed

See, just a gentle hint :P

Definitely finding examples is the hardest part of reading math right now for me

I have tried to play with spaces again to fill in that gap of mine

@TedShifrin Yeah, I feel like I don't learn if I just look at the answers for help, need to do it all myself

scheme theory is the main thing that's rekking me in that regard

is it possible for $\lambda^*(A)$ and $\lambda^*(B)$ to be finite but $\lambda^*(A \cup B)$ to be infinite, where $\lambda^*$ denotes Lebesgue outer measure?

@Alex: My adviser once commented, "Good mathematicians can prove lots of theorems. It's the great mathematicians who can do examples."

I like it

@Lewis: I wish there were never answers. :)

It's making me feel terrible because I'm realizing I am really bad at using all this encyclopedic knowledge I have in my head, but it's working out

My advisor said "It's also good to do math from time to time" in reference to me reading from a few different textbooks

Hell no, @Leaky.

@TedShifrin true

@Alex Scheme theory is too technical, I have heard it's easy to get lost in the vines in there

@TedShifrin oh nvm, I got the inequality in my head in the wrong direction

Vines of abstraction, as in

What's a burgeoning area of research mathematics these days

I'm really glad I learnt some classical algebraic geometry so I can analogize with concrete examples whenever you guys talk about schemes and shit.

@BalarkaSen Yeah, I'm starting to read through shaf 1, and scheme-ify everything I pass

Nice!

So I can get the proper intuition

That sounds like a great thing to do

i was talking to profs about quals - and basically all of them said we're not really going to bother with proofs but just examples

so $\lambda^\ast(A \cup B) \le \lambda^\ast(A) + \lambda^\ast(B) \le \lambda^\ast(A \cup B) + \lambda^\ast(A \cup B) = 2\lambda^\ast(A \cup B)$

so if $\lambda^\ast(A \cup B)$ is finite, then everything is finite

anyone uses matematica here?

Hi leaky :D

@KasmirKhaan hi

I have decided I'm going to go through some geometry/topology qual papers to get the "using stuff" skill going

@loch: It's too easy for most people to memorize proofs of theorems. Working through examples requires more understanding. When I was on a few qualifying exam committees where you are, I generally asked more for examples. Didn't go over too well :P

Yeah, Kasmir, although it's been a while.

I have a Mathematica primer on my university homepage you can steal.

for schemes personally i think it would be great to also read a bit of ch 4/5 of hartshorne, or the chapter on curves etc. in vakil (depending on which is your favourite source for ag) - even without mastering the technicalities in e.g. ch2 and 3 of hartshorne

What's a burgeoning area of research mathematics these days

@TedShifrin haha thanks but no need! :D

What's the need, then, @Kasmir?

i think hartshorne recommends this somewhere in the introduction too... or at least he says it's possible to jump to ch4

@loch I've heard people say that they hate those chapters, but that's an interesting idea

Burgeoning, that's a nice word!

@TedShifrin yeah - so my summer plan is really to make sure i know how to do examples :p

@TedShifrin how to compute this expression , (ln(x)+e^4(x-1))^17

i want to first make it understand that expression

@loch: You'll notice that there are some substantive examples in those papers I sent you.

then to take derivatives of it

It's ridiculous, @Kasmir.

I assume you left out parentheses.

It's just going to be a gigantic mess. What's the point?

lol

Hmm on walfram alfa it makes sense

am learning matematica Ted

Binomial theorem?

Mathematica is no different from Wolfram Alpha.

just that :D

You need the right syntax for Mathematica.

@Alex hmm that's weird. maybe they just don't like how hartshorne does it? in which case vakil does a pretty good job too - for example in understanding genus 2,3,4,5 curves by considering their canonical embedding. eg you'll find that via the canonical embedding genus 3 curves are given by an intersection of a quartic and cubic in $\mathbb{P}^3$ etc. which i thought was really nice - and the only thing you really need is riemann-roch and know a little bit about sheaf cohomology

hmm let me try it again

So why are you ignoring my primer if you know nothing about how to write stuff in Mathematica?

I did not know what primer is

i thought it was the program ><

Um, no.

@loch I've heard that hartshorne isn't really good for introduction because everything is done in high rigour and low intuition (high rigour is not really a problem, but low intuition is)

because i have it , let me get that primer!

haha

It's something with some simple examples and explanations.

oh link please? :D

@loch Interesting, I'll give it a go

also intersection theory is cool - and surfaces is kind of the first place where you see stuff in action. for example once you have the machinery set up - then bezout's theorem (that degree d curve intersect degree e curve at de points) follows from the obvious fact that d lines intersect e lines = d*e points

@LeakyNun yes hartshorne is hard

so... hardshorne?

Hmm, oh, I think the UGA homepage is linked in my profile here.

okay

thanks Ted ! :D

I couldn't get beyond chapter 1 of Hartshorne

@BalarkaSen It's not nice to laugh at your elders!

That's basically a terse summary of Shafarevich chapter 1

Does anyone else incorrectly read it as hart-shorn, rather than as hearts-horn

(Which is a long ass chapter)

@TedShifrin I was laughing at your use of adjectives, not you!

BTW, for people wanting to see examples in algebraic geometry, I highly recommend Joe Harris's introductory book (not Griffiths/Harris).

When you say Shaf @BalarkaSen, do you mean shaf basic algebraic geometry, or his other volumes?

@Alex I read it as Heart-shorne.

@Alex isn't it hart-shorne?

@LeakyNun haha - if you are interested you might consider trying vakil. personally i think the best way to learn these stuff (or really anything in general) is just having someone who knows these things to teach you lol

On a scale of 1-10, how much does Hartshorne warrant the reputation of 'hardness' it has acquired?

No, @Leaky. But I only learned it when I took courses from the man himself.

@TedShifrin That's a beautiful, beautiful book

Amnon Neeman told my friend it's Harts-horne

Yeah, it's Harts-horn.

Huh

yes harris introductory book is filled with examples! (and many of them are not covered in eg vakil or hartshorne etc.)

Illuminati

Never knew that

> The name is pronounced Harts-horne; the sh is not a digraph, as this is a compound. However, locals pronounce it "Artsun".

interesting

Yeah, and I am having trouble untraining it :P

I also say Weibel as Vie-bull

Oh wait. I take it back. I'm confuzled.

Even though he's american

No, I think it is Hart-shorn, dammit.

hides head in shame

Wait what why?

there's a joke that the book is called heart-shorn while the person is hearts-horn

Lol AG is always one of those things I say I should look at and never actually do

LOL

Hahahaha @EricSilva

I'm reading Kirwan's Complex Algebraic Curves; does anyone who knows the book know how much it prepares for eventually learning algebraic geometry?

@Alex why, bull?

@TedShifrin it seems we have a mo verification of the pronunciation hearts-horn: mathoverflow.net/questions/20283/…

Probably sounds less wrong in australian :P

Ugh, now I really don't remember. My instincts were that he preferred Harts-horn, but now I'm not sure.

@Symposium Interesting, I didn't know that book.

Amnon Neeman claimed it was Harts-horn, so I'll go with that too

Yeah, I think that's right. My mind doesn't go back to 1975 too easily.

> Complex multiplication is a more difficult operation to understand from either an algebraic or a geometric point of view. Let's do it algebraically first, and let's take specific complex numbers to multiply, say 3 + 2i and 1 + 4i.

the first sentence is very deceiving

Let's compromise the two pronunciations: Hearts-shorn

I thought it's talking about the real complex multiplication when I read the first sentence

I think if we look up some video where hartshorne is introduced (e.g. in a talk) then we'll know what the official pronounciation should be..

@BalarkaSen I'm enjoying it very much, but I've no perspective or reference to compare it with, if that makes sense.

@Daminark Hahaha excellent idea, I'll say that to him if I ever meet him

Well, no, @loch, as some presenters mangle names.

Ahh, it's written by Frances Kirwan. Very famous mathematician.

Anyway I have become motivated again as planned, so time to do some work. I'll read some steenrod - afk for now

See ya, @Alex.

See you!

so why is complex multiplication called complex multiplication? @loch

@Alex I'll read something from there too, and we can exchange knawledge

the privilege of having an easy to pronounce name is immeasurable i guess @Ted

@LeakyNun uhh do you mean for elliptic curves?

sure

(or abelian varieties in general)

or do you mean multiplying complex numbers

I don't know

@loch definitely not this

Some people have trouble with mine, @Eric, and the spelling throws up arms

lol ive seen your name spelled with various numbers of fs

and some put in a "c"

Schifffrinne?

lol wut

right. My dad was a composer. There was also a guy named Lalo Schifrin who wrote scores for movies and TV.

if i heard your name on the streets id think minimum 5, maybe 6 fs in there

Is it not spelled she-frin

"Tedd"

LOL

Ted Schif F. Frinne

where F. stands for Fffffffffffffffffffffffff

Федор Шифрин

Finally we got it right

@loch I literally know nothing about this thing

anything

this looks like moon speak to me

silverman's very accessible undergrad level book on 'rational points on elliptic curves' talks about this in chapter 6, and again in his other books iirc

Lol just yesterday my algebra prof briefly told me about that kinda thing actually

I'll just go back to my measure theory... :P

Wait when'd you start doing measure theory? Lmao

let's just say complex multiplication is the multiplication of complex numbers :p

I'm cool with that, @loch.

@Daminark kinda today

i need to review my measure theory but i keep falling asleep when i try

Why do you need to review it?

@loch complex multiplication be like $(1+2i)(3+4i) = -5+10i$

Lol, yeah similar. I kinda want to learn about stuff like L^p spaces and Fourier analysis

some probability stuff for the SPDE project im doing this summer @Ted

(L^p spaces as in, stuff like interpolation and all that)

Ah, fair enough, @EricS.

Hmm, $X$ is a $n$-dimensional CW-complex and $Y$ is an $n$-connected CW-complex. Is it obvious without machinery that any map $X \to Y$ is nullhomotopic? I want to say cellular approximation, but that would require $Y$ to be $(n+1)$-connected, I think, because $[X, Y] = [X, Y^{n+1}]$ by cellular approximation.

OK, I need to get back to the kitchen. Bye, y'all.

save me some @Ted

You're welcome any time, Eric.

Hey

But I can remodel the CW complex $Y$ so that $Y^{n+1}$ is a wedge of $(n+1)$-spheres

How do I graph a function with a real and complex variable in it. All the complex plotters only let you use complex variables

I think then schoomschooping does the trick.

I've that Silverman book. It's first book that made it feel it's possible to learn some reasonably exciting mathematics without jumping through hoops!