@Charlie Guess what?

I have a chem test tommorow

@JasperLoy ...and then get a mark or two knocked off for not writing my name :)

It happens

@JasperLoy Haha! I actually had the Lord of the Rings theme song stuck in my head today.

@BillDubuque Hello Professor!

Bye Professor!

@anon Hello Stranger.

yo

@anon Tú?

Who are you gonna nail today?

I accidentally clicked not sure out of reflex instead of invalid.

That's a good default, though. Good reflex, good.

@PeterTamaroff me

@anon Thanks Captain!

you're welcome

@JasperLoy [Accepted].

@JasperLoy Yes, I know.

@Argon jeez..are you ready?

@Charlie We will see tommorow :)

I hope so

I still have some work to do

@Charlie In fact, I had a hydrocarbon quiz this morning

@Argon piece of cake...

@Charlie It was...

Just nomenclature

@Argon jeez I was so good at that! only10/10

@Charlie First question was to draw cyclopropane with a line drawing :)

@Argon :D

whats up with the site.. i cant post questions

Why not?

it says 'Oops something bad happened'

@dukenukem Seems fine for me

dukenukem!hahahaha

@dukenukem then do this

@MattN.

@Ian wassup, bro?

@Charlie Hi! Everything fine. And you?

@Charlie I think I totally confused you with someone else lol

@IanMateus bem.ok

:)

@Charlie It was really weird because I totally thought you were another person. I'm still impressed

Does anyone know what a hydrogen bond is intuitively?

@IanMateus who?

@Charlie Gustavo.

@IanMateus oh

@Argon Intuitively is such a misunderstood word! I am going to sleep though, so I would not expand on it. And it is fitting that argon should wonder about what bonds are (since he does not have them.) :P

@Charlie Do you know him? Are you Gustavo? I'm confused

@JayeshBadwaik What I REALLY hate about chem is that it does not seem logical from my ignorant perspective.

@IanMateus i know him..but i'm not him

@Charlie oh, I see. Now I'm loling about this

@IanMateus hehehe acontece

@Charlie ele nunca mais apareceu, ou é impressão minha?

@IanMateus disse que tava meio fora.coisa dele

@Charlie Como?

@Ch

@IanMateus ah,sei lá...

@Charlie Estranho. Ei, quantos anos você tem?

@IanMateus 20.e tu?

@Charlie 15

@JayeshBadwaik I have a good python script which does a good job in exporting good .bib from Mendeley, now it needs some emacs bindings!

Some short one would be just to run the script.

@Charlie Qual cidade? Não conheço quase ninguém do Brasil aqui (nem de lugar nenhum hehe)

Removes some pain from large projects.

@IanMateus sampa

@Charlie sério? Estuda onde?

@IanMateus num lugar aí... :P

@JasperLoy So, Mr. Loy, how's your mood today?

@JasperLoy flagged?for what?

@JonasTeuwen Jonas,

@JasperLoy now you will have to tell me!

@Charlie For some sexual innuendo

@PeterTamaroff what???

@JasperLoy it's nothing...

c'mon

Did one of you steal my pen?

@anon Yes.

Sold it on eBay.

@MattN. Matt

Yes?

Sorry having a terrible day.

@MattN. Here

@anon yes.i 've been hiding it from you

Poor me.

@MattN. Oh noes. What happened?

Ok. Let me look.

@PeterTamaroff It's a long story. Short version: I made the same mistake a second time.

@JasperLoy How we say here:"Que frescura!"

@MattN. Math related?

@PeterTamaroff You just got an answer. Hope it's sorted.

Main Chatroom Etiquette Rules | LaTeX Support for Chat

How can I show that, a sigma algebra can not be generated from any countable collection of sets?

@JasperLoy once i thought i was without my glasses...it was in my face...

@PeterTamaroff Not at all. Although the effect is that I've done $\cong 0$ maths during the last 3 weeks. And the longer this period stretches the more depressed I get.

But it's self-inflicted.

I should've known better.

@JasperLoy I suppose. It's mainly for newbies, who may not look at the whole right side though. It'd probably be okay being removed though.

Beat me with a stick.

@anon Do you have a minute and some commutative algebra knowledge?

let's see

I wrote a proof the other day but I'd like someone to point out its flaws. Hold on.

@MattN. Let's see!

staggers towards the door

I've been meaning to start a discussion on those chat etiquette rules. They seem obsolete and overwrought. I in fact have a draft of my own version.

This one.

I think I have proven $$\int_0^\infty \frac{\sin t}{t}dt=\frac \pi 2$$ using the Riemann Lebesgue Lemma

@anon I won't have any opinion. I don't really visit here anymore regularly.

@JasperLoy Today I'm here cause I got stuck on a puzzle : )

And also because I've been meaning to ask someone to have a look at that proof I came up with the other day.

who told you it was a good idea to use \iota as an index variable? :|

Haha : D

Just yesterday I had 99 questions.

While writing I first wrote $i$ then changed it to $j$ then to $\iota$.

I have too few to be frivolous.

@JasperLoy I won't solve it today. I've had half a bottle of sake and even before that I was in no state of solving puzzles.

@MattN. Seems perfect to me.

Curved space.

@anon You are awesome, hugs!

Or someone did an inverse trig function and picked the wrong value.

That is the best news I've heard in 3 weeks.

This is so pleasing.

Thank you.

Those were simple things...

@JasperLoy It won't. Angles in triangles sum to 180.

@anon I was so pleased when I found it. And the day after felt so bad cause it turned out to be a duplicate question :,(

That's not a proper puzzle!

If this was a bar we'd have a bar fight now.

@ablmf Isn't the power set of $\Bbb N$ a $\sigma$-algebra generated by the countable family of singletons?

@anon, I know sigma algebra can be generated from countable family of sets

But I need to find an example of sigma algebra, which can not be generated from a countable family of sets.

@ablmf Oh. Why, take the sigma algebra generated by the singletons of an uncountable set! (i.e. the collection of all countable subsets of an uncountable set)

the generation process is just countable unions, right?

@anon, then how can you show that, there is no way you can generate this sigma algebra from a countable family of sets?

Wait, that's not even a sigma algebra because it's not closed under complements, what am I thinking?

@Jasper, it could be uncountable, right? Think about Borel sets $B(R)$, it can be generated from a countable family of sets.

@JasperLoy Yes I have. Was out with some friends and they wanted to grab a burger (it was late Saturday night) and we were standing outside macdonalds. A bunch of Eastern Europeans (South, not sure exactly where, perhaps Turkey or Albania) said to one of them: You have a problem with my friend? You gave her a funny look? Then he punched my friend in the face several times while giving him a half nelson.

Not actually a fight since we didn't respond to it.

Nor did any of us give funny looks to anyone.

But lucky it was the young me back then.

My current me would totally beat the crap out of the tard.

I don't know.

And I don't care : )

Indeed. And maybe a bunch of others.

It doesn't help, but I seem to recall proving that any infinite sigma algebra must have an uncountable number of sets

Is there something really difference between dynamical system and chaotic system ?

dynamical systems needn't exhibit chaos?

chaos is special case ?

of course :-)

The equation $X'=0$ gives a rather unchaotic dynamical system!

Alright, how about this: the $\sigma$-algebra generated by a family $\cal F$ is a subcollection of the power set of $\bigcup\cal F$. Therefore, if a $\sigma$-algebra is countably generated by finite subsets, it must be bounded in size by continuum. Now pick a $\sigma$-algebra generated by finite subsets that is bigger than continuum.

Nevermind, complements again.

I'm recently doing the mini-project in a modelling course about cellular automata, just very excited about chaos. It's amazing thing that some books there showing CA can even use some Grothendieck theorem in algebraic geometry

Night. Thanks @OldJohn and @anon

@MattN. night Matt - let me know if you get a final solution to the fly problem!

(I still have one case that is not settled in my mind)

@OldJohn I will if I do but I won't work on it anymore. I'm reading a book which asks me to do lots of these but I can't stand puzzles and recreational maths. : /

So I will just move on to the next one.

To get it over with.

@MattN. OK - no problem - I understand

While still trying to learn as much as possible from it.

: )

@MattN. that is the aim, I guess :)

Have fun!

Haha, thanks. Being stuck on one of these feels like a complete waste of time.

@MattN. You are right - some problems are OK to be stuck on for a long time, as they eventually lead to useful techniques ... but some are really not that productive