The h Bar

0celo7

8:00 PM

they at least knew the radioactive stuff wasn't good, and kind of contained it

they just put tons of Hg in the woods

random places in the woods

Anonymous

Is it possible to decontaminate radioactive regions? I had heard that research is going on

0celo7

@Blue There is. What they've done is put concrete slabs over everything to minimize contamination and limited people accessing groundwater from those areas

the actual effects are minimal

Anonymous

That's nice

0celo7

I need to order some school books. Yay

Stefan Bischof

Yay.

Anonymous

8:04 PM

"school" books?

Anonymous

@StefanBischof Hi

0celo7

@Blue what?

Stefan Bischof

Sci-Fi books to read during Class xD Not something to actually learn?

Anonymous

@0celo7 school=uni. Or did you mean something else?

0celo7

yes

what else would school mean

Anonymous

8:07 PM

Actually it quite rare to use school as an alternative for uni in this part of the world

Anonymous

:P

Anonymous

Anyway

0celo7

it is a school

we call the departments schools

or colleges

either works

Sid

Why is Uni not called College?

AH, that's better.

0celo7

@Sid I call it college

@Blue's mastery of English is doubtful

Sid

8:09 PM

LOL

0celo7

(see what I did there)

ok @Blue I'm bored

let's learn some measure theory

Anonymous

I want to learn AI stuff

Anonymous

Life's so short.

Anonymous

Meh

0celo7

if you want to learn mathematical QM you need measure theory

Speactral theorem and whatnot

Anonymous

8:11 PM

Maybe, someday, I will learn it :P

Stefan Bischof

Maybe learn about neural networks for use in AI? Play around with digital neurons: playground.tensorflow.org

Anonymous

@StefanBischof I don't have time XD Ok, I'll look at it. Thanks

Stefan Bischof

@Blue Ok :) It's an intuitive app instead of a long text.

0celo7

well what do you have time for?

Sid

I wonder how a freshman year guy has no time.

0celo7

8:14 PM

your savior the lord Jesus Christ perhaps?

Stefan Bischof

@0celo7 Eat, happyness, playing Hearthstone

Balarka Sen

AI reminds me that I should take a look at that 11 dimensional brain thing

Anonymous

@Sid A freshman year guy who has enrolled for 5 courses on Coursera and learning QM and Linear Algebra on their own.

Mithrandir24601

@Sid It depends where in the world you are - for me, a College is very different to a University. There's a type of College that you could go to pre-Uni ('6th form College'), a College you could go to instead of a Uni, ~1 you could go to that is a Uni and a number that are parts of different Unis

Balarka Sen

@0celo7 Nope, not yet

0celo7

8:15 PM

@BalarkaSen It's deeeeeep

Sid

@0celo7 If blue is refusing to even look at Measure theory, I doubt he wants to learn about God. :P

Balarka Sen

I sort of wanted to learn more extrinsic geometry but ran out of motivation fuel

I really enjoyed 6.2

Anonymous

@0celo7 Studies.

0celo7

tfw the apartment randomly shakes

how does that even happen

Mithrandir24601

@Sid First week of first year, we were sat down in my Director of Studies office and he listed out everything that was the minimum we needed to do and it totalled to 55 hours minimum per week. 'Minimum' is just about enough to pass...

Balarka Sen

8:17 PM

apocalypse has come, @0celo7

Sid

@Mithrandir24601 ....what? i don't understand any of that

0celo7

@Sid lol me neither

Sid

@Mithrandir24601 Wow... we have only 23 hours of classes per week this semester.

0celo7

@BalarkaSen check out the book "Curves and Surfaces" in the GSM series then

Sid

@0celo7 Earthquake. Enjoy that.

Anonymous

8:18 PM

@Mithrandir24601 Mine totals to more than 100 including the self-study courses :P

0celo7

I think that's a deeper look at surfaces that's not just a PDE orgy

Stefan Bischof

To drop a random fact about neural Networks: Instead of a CPU at the beginning of 2017 IBM introduced en.wikipedia.org/wiki/TrueNorth Instead Transistors relying on synamipsis/neurons

Anonymous

But okay, I should just stop complaining and get on with my work

Anonymous

:)

Mithrandir24601

@Sid Essentially, I'm in the UK and (except for the I believe 1 University College London) a College $\neq$ University

Sid

8:19 PM

@Blue You brought it upon yourself

0celo7

@Blue 100/7 = 14.3

you are not doing 14.3 hours of work a day

Sid

That. ^

Anonymous

@0celo7 Of course I am.

Balarka Sen

@0celo7 Sighh. I don't know, I still need to learn Jacobi fields.

Sid

Ridiculous

Balarka Sen

8:19 PM

I am just so clueless what resonates the best with me in differential geometry.

Mithrandir24601

@Blue That sounds more like the actual work we had to do :P

0celo7

@BalarkaSen so you're not a geometer

why are you trying to force it?

Sid

@Mithrandir24601 Oxford and Cambridge are not Universities?

Balarka Sen

@0celo7 ... That's a good question.

Anonymous

@Sid Okay man. I don't want to prove anything.

Mithrandir24601

8:21 PM

@Sid Yeah, they are, but they're not Colleges - they're formed of Colleges

Anonymous

I am enjoying it

0celo7

I am supposed to now get 12 books on fluids

My advisor looked at the book list for my fluids class and added 5

what the hell is wrong with everyone

Sid

@0celo7 ....what? I am going to eat my shoe if you are able to read all 12 in a year

0celo7

@Sid exactly

some of them are 700 pages long

Sid

@0celo7 Your advisor is a dumbo

0celo7

8:22 PM

@Sid I wouldn't say that

Mithrandir24601

@Sid Get up at 7am, start work at 9am, stop for lunch at 12.30pm, start work again at 1pm, have dinner at either 6 or 7pm, start work an hour later (I gave myself an average of an extra hour per day at this point to do other stuff), then go to bed at about 1am

Balarka Sen

why y'all ranting about workload

if you don't like workload don't work

if you like workload work

0celo7

although he does give me books that he hasn't read but owns in hope I tell him it's worth reading

Balarka Sen

just stop ranting man

watch some dank memes instead

Mithrandir24601

Repeat every day (except for major, major holidays) for 3 years

0celo7

8:23 PM

@BalarkaSen we can't all do weed enemas like you

Balarka Sen

I guess lmao is a good response to that

but weed is for kids

0celo7

@Mithrandir24601 and look where that got you

Sid

@Mithrandir24601 ....That's too heavy a workload.

0celo7

shitposting in a chatroom with a bunch of Indian kids

Anonymous

@BalarkaSen Uh, well it all started because @Sid claimed that a freshman year student can't have no time.

Mithrandir24601

8:24 PM

@0celo7 Doing a PhD that I can't help but love :D

4

0celo7

@Mithrandir24601 I thought you were a PhD student

$165 global.oup.com/academic/product/…

Mithrandir24601

@0celo7 That's what I meant... I edited it to be more clear :P

0celo7

ayy

I can get it on Amazon for 48

still a bit much

Mithrandir24601

@0celo7 Oh, the above 3 years were my undergrad...

Balarka Sen

@Blue That's true. None of us has enough time.

too much too learn

too little time

soon we all die

<3

Anonymous

8:27 PM

Either I want to die fast or not die at all. I don't like anything midway

Anonymous

:P

0celo7

@BalarkaSen Got an idea why on $T^n$, $-\Delta u=f$, $f\in C^\infty$ has a solution iff $\int f=0$?

Using Hodge theory is cheating

Balarka Sen

nope

Mithrandir24601

@Sid Yeah, I was borderline burned out after 3 years - I only really managed to fully recover from it a few months ago :P

Balarka Sen

@blue janar kono shesh nai, janar chesta britha tai

as a wise man once said

0celo7

8:28 PM

please no indian

Balarka Sen

bengali \neq indian

that's a \ne!!!

Anonymous

indian is not a language...lol

0celo7

bengali $\cong$ indian

Sid

@Mithrandir24601 I got burned out after 2 years of High School. :P

Anonymous

nah...bengali is congruent to bangladeshi

0celo7

8:30 PM

that means isomorphic

Sid

But, that had more to do with the amount of competition than heavy coursework

0celo7

learn some aljabr

Anonymous

i'm larning linear aljabr

Balarka Sen

actually i feel like bengal represents little to nothing about the generic india (in terms of language, culture, etc etc).

we're kind of an isolated bit of it

for geographical and historical reasons

well except the JEE craze

0celo7

@BalarkaSen I'm actually pretty excited for that algebra course. It's taught by my former topology prof, who's a famous knot guy

Balarka Sen

8:33 PM

Sounds nice

0celo7

@BalarkaSen today he brought in this book "atlas of finite groups" by Conway

Anonymous

@BalarkaSen There is no "generic" India. Every few hundred kms it changes drastically

0celo7

it's absolutely huge

Balarka Sen

@Blue That's fair, I guess.

Oh I have heard of Conway's book

0celo7

@BalarkaSen he was a grad student when they were writing it

they had the character tables spread out on the floor trying to figure out how to organize it

Anonymous

8:36 PM

Anonymous

@LeakyNun How are iterators helpful?

Anonymous

Can't we just use next() and hasNext() directly

Leaky Nun

@Blue you also need hasNext()

Anonymous

@LeakyNun Yeah. I mean why do we need such an interface?

Leaky Nun

@Blue because you want to be able to iterate over the same iterable twice

Anonymous

8:42 PM

@LeakyNun Ok. As an alternative for the while loop?

Leaky Nun

@Blue I don't get what you're asking.

Anonymous

8:52 PM

@LeakyNun Alright. I'm trying to break down my question into parts:

Anonymous

Iterator is an interface with next() and hasNext(). Okay so far

Anonymous

Now, what is the use of the Iterator<Item> iterator() ?

Anonymous

We are defining a generic datatype

Anonymous

But how can a function iterator() be a variable of Iterator<Item> type?

Anonymous

Functions aren't variables...right?

Anonymous

8:56 PM

I'm finding the syntax confusing

Anonymous

Or I should revise generics

Dawood ibn Kareem

9:07 PM

@Blue In Java, the order you declare things doesn't matter. There's no reason why it should.

vzn

Rumours swell over new kind of gravitational-wave sighting / nature

Dawood ibn Kareem

@Blue What would you put in your while loop, if you didn't have iterators?

Anonymous

@DawoodibnKareem Yeah. I got it now

Dawood ibn Kareem

@Blue No, iterator() is a method that returns a value of type Iterator<Item>.

Anonymous

@DawoodibnKareem Then can't we just write return abc.iterator() ?

Anonymous

9:11 PM

abc being any object which is invoking the function interator()

Dawood ibn Kareem

@Blue Yes, but what context are you doing this in? You're asking general questions about very specific code, which you haven't shown.

Anonymous

@DawoodibnKareem Scroll up a bit. You'll see the screenshot

Anonymous

Look at the top right

Anonymous

I can't understand what the interface Iterable is doing

0celo7

9:16 PM

@BalarkaSen Well I proved it but in the end I just repeated the proof of Hodge's theorem

success?

Phase

Could anyone point me to source for, or tell me about, co-ordinate transformations between say, some linear velocity co-ordinate frame and one like the earth? I.e accelerating but in circular motion

0celo7

@Phase What?

Phase

Well between linear velocity frames of reference it's just the lorentz transform

But what about one with no proper acceleration, and one that is in circular motion?

Anonymous

What a co-incidence. I was thinking of asking the same question as Phase on the PSE main site. :P

Anonymous

I'd like to know the answer

Leaky Nun

9:21 PM

@Blue because you want to be able to iterate over it twice

you generate a new iterator every time iterator() is called

Phase

Oh

That is spooky

I just tabbed to this after hours of playing vidya

Anonymous

@LeakyNun Iterator<Item> iterator()....what does this particular line mean/do?

Leaky Nun

@Blue it is an abstract method

you get a brand new iterator if you call the method

Anonymous

Shouldn't abstract methods be overridden? I can't see where they did that

Anonymous

@LeakyNun

Leaky Nun

9:24 PM

they haven't. you should do that.

Anonymous

Oh I see

Anonymous

@LeakyNun Also, what is the Iterator<String> i=stack.iterator() doing? If we are creating a new object of Iterator<String> type, the should'nt we write something like Iterator<String> i=new Iterator<String>() ? And what is stack here?

Leaky Nun

@Blue stack is the previous stack which stores strings :)

we are getting the iterator of the stack

Anonymous

@LeakyNun You mean the overridden iterator() , right?

Leaky Nun

yes

Anonymous

9:31 PM

Aha

Anonymous

Gotcha

Anonymous

Thanks a ton :)

Leaky Nun

no problem

Anonymous

@LeakyNun You codegolf profile is quite impressive. Have you been learning coding by yourself (beyond the normal schoolwork)?

Leaky Nun

@Blue yes

Anonymous

9:35 PM

@LeakyNun Nice. I would like to know how you got started. Did you take MOOCs or read books or something else? I've started solving the basic Algorithms and Data Structure problems from sites like HackerRank and CodeChef but I'm not sure of the order to follow

Leaky Nun

@Blue my father taught me programming when I was young

well, I'm still young now, but whatever

Anonymous

@LeakyNun I don't think he taught you the advanced stuff, or did he? :P

Dawood ibn Kareem

@Blue All that means is that if you have a class with a method called iterator()that returns an Iterator<Something>, you can declare that it implements the interface Iterable<Something>, then refer to it with a variable of type Iterable<Something>, or use it in some other context where an Iterable<Something> is required. One special example of such a context is a for-each loop. Something that implements this interface can appear after the colon.

Anonymous

I know just basic java. Not sure how to move on from here. Enrolled in some MOOCs

Leaky Nun

@Blue well what do you want to learn?

0celo7

9:39 PM

@BalarkaSen algebraic topology bat signal

Anonymous

@LeakyNun I'm mostly interested in competitive programming, simulations and machine learning /AI

Balarka Sen

@0celo7 [Raspberry voice] You called?

Leaky Nun

@Blue the last one is way out of my expertise and the first one is mostly algorithms?

0celo7

@BalarkaSen Raspberry?

Anonymous

@LeakyNun Yes. The first one is mostly algorithms

Anonymous

9:41 PM

How did you go about it?

Balarka Sen

I meant the Batman voice lol

What's the q?

Anonymous

Any suggestions how to strengthen my algo skills?

Leaky Nun

@Blue practice.geeksforgeeks.org seems to be a good site

Anonymous

I heard good things about that site

0celo7

@BalarkaSen I have an open set $\Omega$ in $\Bbb R^2$, and I'm looking at the graph of a smooth function $u:\Omega\to\Bbb R$. So this surface lives in the cylinder $\Omega\times\Bbb R$. I want to compare this with other surfaces in the cylinder that agree with $\Gamma(u)$ on the boundary

The claim is that $\Gamma(u)$ is homologous to any such surface, but is this true even if they intersect in the interior?

Balarka Sen

9:43 PM

Yes.

0celo7

@BalarkaSen But the cycle will not necessarily be a manifold

Balarka Sen

Um, which cycle?

0celo7

I mean chain

Balarka Sen

The nullhomology chain?

0celo7

If $\Sigma $ is such a surface I want a chain $c$ s.t. $\partial c=\Gamma(u)-\Sigma$, no?

Balarka Sen

9:47 PM

right, that's what I meant

Well, no, I don't think $c$ is necessarily going to be a manifold

Like take graph of a function over a closed interval for a baby example

0celo7

yes

that's what I drew

and why I'm asking

Balarka Sen

You can take the other curve (analogue of $\Sigma$) to intersect it a bunch of times, like you said

So, no, $c$ is not in general going to be a manifold

0celo7

maybe not a manifold, but will Stoke's theorem work on it?

Balarka Sen

Yup. You can integrate over chains, right?

By cubulating the chain

0celo7

Right, but is this actually what one calls a chain in the Stokes sense

Balarka Sen

9:50 PM

Right.

The chains in the smooth context are cubulated chains, not triangulated chains as in topology

0celo7

According to Lee, they are smooth images of simplices

(or linear combinations thereof)

Balarka Sen

I have always seen smooth images of cubes.

0celo7

I thought you didn't know geometry

In any case, we have these surfaces

It seems pretty obvious what $c$ should be

But how does one actually check that it's a smooth chain?

Sir Cumference

10:04 PM

heather

11:15 PM

hello

skullpatrol

hi

Mithrandir24601

@heather Rytsas!

heather

@Mithrandir24601 rytsas =)

4

Q: Discussion groups to assist those self-studying or enrolled students

Recently, there has been a lot of discussion about an idea MathematicsAminPhysics came up with - a "MSE University". I think there was a meta post as well, though it seems to be deleted. While this idea grew out of that, it is not that, so please keep reading with an open mind. The idea to me s...

discussion

^ people here might be interested in the above since MathematicsAminPhysics posted in here too.

Mithrandir24601

@heather I'm potentially willing to be a little involved, but I am really busy with working, although from October, I'll get paid to help out in demonstration classes :)

heather

cool! i'll probably post updates on this topic here.

heather

11:38 PM

and second relevant post to the above:

0

Q: A call for volunteers - "study group" coordinators and advisors

You may have read my meta post Discussion groups to assist those self-studying or enrolled students (if you haven't, you probably should, though a quick summary is provided below). Again, this idea grew out of the idea of a "MSE University" but it is not that, so please keep an open mind. So, ...

discussion

Mithrandir24601

@heather what level is this geared towards - I'm a PhD student, so should I be a student or volunteer? (both?) When I say I want to teach/learn something, how do I know what level it'll be at?

heather

you could be both, yes.

you might be able to teach calculus but want to learn topology (bad example, but hopefully you get what I mean).

probably best, in a situation like yours, to make clear the level you want to learn/teach at.

Mithrandir24601

OK, is it just maths subjects for scientists, maths for mathematicians, or maths+science for whoever?

(don't get me wrong, this is a fantastic idea - I just like everything to be clear when I'm doing this sort of thing)

heather

11:54 PM

for right now, it's math. who it's for doesn't matter.

maybe if this works well it can expand. but really, right now, the one goal in mind is to start a single trial course, with something like calculus, where many would be able to teach and interested to learn, just to get it started.

Mithrandir24601

@heather Ah, OK. I think, for something like that, I'm willing (and apparently qualified) to teach that at some level (for physicists at least) but not by myself. i.e. I'm able to help a lecturer teach the course when someone has questions or a difficulty with something, so I think you need a middle 'demonstrator' level - you have the teacher, the student, then the demonstrator helps with students' questions, difficulties etc. but doesn't go through the main points with the students.

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