np @AlecTeal I was just taunting him pal };-)

If $X=\{0\}\cup\{\dots,\frac13,\frac12,1\}$ and $Y=\{\dots,\frac13,\frac12,1\}$, then $Y$ is dense in $X$ despite the fact that every element in $Y$ is an isolated point.

In other words, $X$ has a dense, isolated subset.

I thought that was interesting. The notions of dense and isolated seem kind of contradictory, but it turns out they're not.

Puzzle: Find $X$ and $Y$ where $X$ is uncountable and $Y$ is countable, and $Y$ is a dense, isolated subset of $X$.

Hey there's like a $\mathcal{J}$ but the loop of the $j$ goes further around, how do I write that in LaTeX?

@AlecTeal Hmm, $\mathscr{J}$

(probably not)

@AlecTeal: Can you write it in paint?

$\mathfrak{J}$

Thanks @TobiasKildetoft

@AlecTeal Ahh, that was the one?

As far as I recall, that is one of the things detexify is not good at: identifying fonts

@Huy you cruel bastard.

Writing $\mathscr{j}$ with a laptop touchpad is a challenge that ought to be confined STRICTLY to Japanese gameshows.

?

^

@AlecTeal: Get a mouse? :P

They're on sale on Amazon pal.

Yeah maybe...

ö.ö

@DanielFischer, How do we get length of that side $Ld \theta$ here?

@Silent: Why do you need the length? You get the equation in the left bottom corner by similarity.

@Huy, will you please explain that? It will be very helpful

On a serious note @Huy don't be a git. Asking you guys "Hey, what's almost mathcal" AFTER finding a PDF that didn't show me is easier than detexifying or trying further search results. By a lot.

@AlecTeal I agree. Finding a specific latex font can be really tricky, but really easy if someone knows it

@AlecTeal: I have no idea what you're trying to tell me but I flagged you because I don't think it is appropriate that you call me a git.

That is why I asked. Thanks again @TobiasKildetoft - I thought it was mathsrc or something!

FINE @Huy - You're a CVS.

Happy now?

@AlecTeal The scr is for "script"

Why script?

(the cal is for "caligraphy")

@AlecTeal such letters are called cursive script (or just script) letters

I know that one, but what would script be? Those jagged ones (frac - or something) - not sure where their name comes from either.

Oooh

@AlecTeal frak is from fraktur (they are gothic letters and I think fraktur is the german word for those)

@TobiasKildetoft while I've got your attention (nice for knowing what CVS is BTW) is there any way to do a BB 1 - like one might use for indicator function? I've looked it up before and it wasn't support by MathJax's fonts, and I've not been able to find it, but as this demonstrates lists like: marseillexuelian.org/Symbols.pdf are hardly exhaustive.

@AlecTeal It is called mathbbm and in the package bbm

it has the blackboard versions of a lot of the letters missing from mathbb

(it also has the blackboard version of $k$ which I sometimes use for a field)

Do you know how to import mathbbm into mathjax or must I look that up?

@AlecTeal No idea if that can even be done

when writing here, I usually make myself content with whatever works without fiddling

Yeah, I just gave up and used $\chi$ in the end

math.stackexchange.com/questions/1386397/… - how quickly will this be closed.

I hate this site.

math.stackexchange.com/questions/1382711/modulus-problem (not my Q) - closed as off topic. But ask a question about the English language - HAVE MY UPVOTES

Thanks for the explanation of a "bitch slap" @AlecTeal

Don't be surprised if a woman flags it.

It's what I'm here for @skullpatrol

Indeed.

Pal.

Thanks for confirming that @skullpatrol - There's a Daniel Farlow who voted to close that question, he didn't like the OP or the fact I answered - so I suspect that was a nasty vote to close, but the others.... it's a MATHS question

Man, figuring out the state of the art on something just slightly away from my main area of expertise is proving really tricky

What are you up to @TobiasKildetoft?

@AlecTeal Working on formulating a project for a grant proposal

*shakes his head

A bitchslap is a kind of slap, not a slap for bitches.

Same difference.

trying to figure out how much is known about algebraic groups (or just general linear groups) over complete local rings

Amateur.

lol

You clearly misspelled "sly reinterpreter of words".

?

There's a question about when to use "an" or "a" @RegDwigнt - and it's getting upvotes, but a genuine maths question was closed as "off topic"

Wait, there's a question about articles on Maths?

What the actual what.

I wasn't asserting though - at any point - that the people who voted to close were bitches.

I simply said I would bitchslap them.

As you can see the distinction is very important.

Oh yeah in that context it most certainly is.

Context is king.

So if you are here to slap bitches, which frankly I find quite sexist, you are most certainly in the wrong room.

Please keep that on misogyny.stackexchange.com

@AlecTeal Why is it sexist to slap female dogs?

It is not up for interpretation whether slapping bitches is sexist. It is sexist by definition. You cannot have an opinion about it.

Oh @TobiasKildetoft - later we shall have a talk.

Frankly, I find sexism quite sexist!

Duh.

Good save @RegDwigнt

I am not saving anything. Not for free anyway.

*cough

I could save ten dollars. But only if you gave me twenty dollars.

Come on guys ^

Be nice

:-)

This is hardly a fight.

@AlecTeal yes so? Or do you have common cold?

....

@RegDwigнt on the banter front your skills are poor, you are only marginally better than someone who says "rubber glue, back to you" in response. Shall we move on now?

Yes

What the hell are you even talking about.

I am not bantering anything.

Shhh

I just say shit.

Time out

I don't need to move on from anything because I never stuck to anything.

I move on all the time.

Sure.

Absolutely every post of mine has nothing whatsoever to do with the last.

And this has been going on for six years now.

Let it go

This is brilliant.

Let's get back to having fun

Please?

Yes!

:-)

So @TobiasKildetoft you said you were working on a grant proposal?

Lol. She said "fun" and he says "grant proposal".

Oh to the em to the gee.

@AlecTeal Yeah, it is an individual grant for a 2-year postdoc. I just need to get a project together that fits with the area of expertise of the professor I am going to be working with

(which is some way from my usual one)

@RegDwigнt we enjoy our subject, if you have a problem with that maybe you should leave.

Would you guys kindly stop flinging flags across the whole network?

@AlecTeal who said I had a problem with it?

oy math geeks, wuddup with all the flagspam??

THIS INCLUDES NOT PROVOKING THEM @RegDwigнt

@RegDwigнt "lol" means you are laughing. So you're laughing and saying:

most of those seemed ridiculous, but then most of us mods have no clue what is appropriate in this room.

@AviD So you saw some flags from this room, and decided you wanted to be flagged too?

Yes. I read that. In fact I wrote it.

@AviD can you deal with @RegDwigнt please, he's come in here and just... I don't know.

@TobiasKildetoft no, I decided to come in here and do my modduty and tell y'all to quiet on down.

@AlecTeal Precisely. I don't know either. Nobody does. "And just..." what?

@AviD But we know what is appropriate for the network. We can freeze the whole things until a maths mod gets back.

Please stop @RegDwigнt

Stop what?

He's not usually here. He came in and started posting about paying to slap bitches.

Please clearly state in English what it is I should stop.

@Oli oh I like that

Posting.

might just do that if it keeps up

oh, well

Yeah why not.

@AlecTeal I enjoy my posting. If you have a problem with that, maybe you should leave.

wow yeah, @RegDwigнt you were the only one who actually said anything flagworthy, to my eyes

and my eyes come from the DMZ, so they are not overly sensitive

Tee hee.

googles DMZ

uncool.

Imma leave now, hope I dont get dragged back in unless its for something real.

Just ignore it.

AFK guys, room is being cleaned

And now, children: behave.

Thanks @DanielFischer

Please leave @RegDwigнt

Seconded.

What is going on here?

@Martin-マーチン Good question. I'm not sure.

A mod came in and has made it really bad.

There's been some... unhappiness about RegDwight.

so there were some flags, some mods came and froze the room

then somebody unfroze the room and the first message by Reg is flagged again

Actually that's not true at all. There were some flags first. RegDwight wouldn't even have shown up otherwise.

jeah i just saw a lot of flags

Well it's over now, can you just leave @RegDwigнt

@Vogel612 and please stop misspelling "Reg". It's Reginald, not Redinald.

oh crap, sorry

@ToolPurger I can, but why? Is my mere presence holding someone back from doing their usual thing?

well this room just became a celebrity :D

@RegDwigнt dont' start.

What? I am not starting anything.

Please just leave.

@RegDwigнt I normally wouldn't interact directly with a mod like this in public, but sure, you're being pretty inflammatory now. If you can't see that, it's time to hang up the star.

aaand there we go again

Okies, can we get a freeze again? This seems to not work

@skullpatrol mod on AskUbuntu

use the chat profile card

PLEASE don't freeze, just leave please @RegDwigнt

All the non regulars leave.

QED

@skullpatrol can we get a please for that?

Please

:-)

:C

Best of luck.

Okay... stay civil and have fun!

Come back when you want to do some math.

Or talk about math.

Please

:-)

Associated with Math.SE; for both general discussion & math questions alike. Just ask; don't ask to ask.

hey

@SohamChowdhury Hi

How's it going?

Urgh, don't get me started.

@AlecTeal: If they "spy on exes and stuff", they - very likely - already did before and not only when they found out "hey, look, I've got a list of exes of Huy, now we need to spy on them too, we never knew before that those women existed!", or do you not agree?

No @Huy they were spying on their own ex partners. But anyway call me old fashioned but I like stuff to be private by default. You don't have to be into [illegal activity here] to not want to have everything about you known to the state.

There's a guy called George Orwell, you should look him up.

1984

+

The Internet

@AlecTeal: Sure, I can completely understand ANYONE who doesn't want to share their private data. But I don't like it when those people run around and tell everyone who simply DOESN'T CARE about it "oh you're so stupid oh you're so fucked", if you understand what I mean.

@Huy a lot of people don't care out of ignorance though.

@AlecTeal: I don't know about your country, but over here pretty much everyone knows what has been happening (and still is), and some people do care and do their best to protect their privacy and some simply don't (including me).

@AlecTeal: I think it is best to let everyone do what they want to do as long as it doesn't harm anyone else?

@AlecTeal: Regarding your condescending mention of George Orwell, I have read some of his books (including 1984), and I still don't care.

@Huy Why don't you care?

@ypercube: I don't feel threatened, intimidated or harmed by it in any way, so I don't see a reason why I should care.

@Huy So you have noproblem with all your conversations being tapped?

@ypercube: Not really, no.

No problem if your going into the shower being taped?

@ypercube: Not really, no.

No problem if having sex is taped and broadcasted on youtube?

That's against YouTube's terms of service.

@ypercube: ^

braodcasted on some site that has no such issues

@ypercube: Also, there's no cameras running in my room when I have sex.

You don't know that

@ypercube: At least none that I don't know of.

@ypercube: I know. ;-)

I'm just asking to see where you put the limit - if you put any.

@ypercube don't bother. This is why I went quiet.

@ypercube those sites would be considerably less popular than YouTube. Like ten people would ever watch the video at all.

@RegDwigнt irrelevant

@ypercube: Do you think WhatsApp/Facebook knowing where and who I have lunch with is the same as taping me while having sex and broadcasting it on YouTube?

As I sadi, I'm just asking where your limits are.

@ypercube I'm not saying it's relevant to you, or even to me. I'm just stating a fact. It might be relevant to some people.

@ypercube: Doesn't really answer my question.

it's irrelevant to the poinst in the discussion we are doing

@ypercube: Maybe to you, but as far as I remember discussions require at least two persons?

isn't you and me 2?

and 3 with Reg?

@ypercube but the point of the discussion is figuring out why some people, in fact many people, are a-okay with this. And some people, in fact many people do say "I'm okay with this because only ten people would ever see it, and they don't even know me, so wevs".

I thought I count count up to 2 at least

Well from my point of view it's just you bursting into this room, trying to make a point and not responding to my questions (which are required for me to make my point).

You only made one question.

@Huy No it's not the same of course.

But when you don't draw a limit, you'll never know when the limits you think would never be passed, will be passed.

Explosions! Flags! Excitement!

@ypercube: I know my limits but as I said: As long as I don't feel threatened, intimidated or harmed, I don't care. I know some people prefer a more anticipatory lifestyle, but I am more of a reacting guy. Each to his own?

Hi pal @GnomeSlice

Please stop flagging things for no reason. If you are feeling angry now, maybe step away from the chat room

What @MattE.Эллен said.

@ypercube: The same people might say "but then it's too late", but that's just like their opinion, man.

^

I give up

Same

:(

Flagging is not for "Things I don't like reading", guys, don't be trigger happy.

@Alenanno you have no idea.

@AlecTeal About what?

Don't ask

I for one have an idea. A business idea. For a popcorn stand next to the entrance to this room. It would make millions.

@skullpatrol (Not much really happened. The mods come in a bit too easily.)

@RegDwigнt Rofl

lol

@Khallil If you flag stuff in chat, it notifies all moderators. It's the flagging that was easy, we're just doing our job.

@Alenanno Also all 10k+ users across the whole network.

Flags are broken. And annoying.

@Khallil I'm not even a mod, but a bunch of random shit was getting flagged bro

Also Edward Snowden.

^

(Oh, I was referring to something that happened over 12 hours ago.)

Why freeze a math room?

Yeah, freezing is really about Physics.

Or chemistry

@RegDwigнt lol dude

Oh look, more spurious flags.

There needs to be a penalty for too many rejected flags.

How can I see what was flagged?

Can someone flag something?

No.

@AlecTeal Easy. 1) Visit this room. 2) Look at all the messages. 3) All the messages that you are seeing have been flagged.

K, stop.

QED

Flagged.

@Bob There is. Like being suspended, for example. :P lol

I predict another freezing

I'm going to come back tomorrow. This is absurd.

0 Kelvin violates the 3rd law of thermodynamics people

:-)

Yeah, putting you guys on mute now.

Stop the freezing

Yeah I can't see that.

He didn't actually flag it

You don't have enough network rep to see flags anyway, though.

@GnomeSlice: That's because we're hiding them. Some people have learned how to do that, and only use them when needed.

Can you guys please stop talking about being taped while having sex and whatnot? This is a math room, not something like privacy.stackexchange.com.

BBL.

@SohamChowdhury I did that. Sorry, it won't happen again.

You guys can always just make another chatroom for off-topic discussion, you know.

How dare you @ypercube and you are supposed to be a perfect cube :-)

To add some levity, here's a cat trying to do some math.

@skullpatrol I lowered to this 2-dimentional room from my usual 6th dimension and got disoriented

@Khallil: Poor cat.

This room has a PG 13 rating.

Too many prodigies

:D

Good morning.

Hi pal

Got up at 4:30 today.

@Owatch That's not a good morning.

@Khallil: What are you working on these days?

Catching up to the latest episode of Gintama, @Huy!

(Really haven't done any work for the past fortnight!)

Such animu.

This has not been a good 24 hours for this room @DanielFischer

Given $\int_{1}^{\sqrt{3}}{tan^{-1}x}dx$, should I go with $tan^{-1}x$ as $u$?

Seems to be the way to go..

@skullpatrol Well, not really. But if people here insist on misbehaving, such things happen.

such a mess

I think you can integrate by parts, @Owatch. Let $u = \arctan (x)$ and $v' = 1$.

@DanielFischer has this room ever been frozen?

@skullpatrol You mean before today?

Yes

I don't know.

it has

Yes, it has.

@Khallil Do you mean $v' = dx$ ?

@Huy $p : \tilde{X} \to X$ be a simply connected cover of $X$. Fact : given any cover $E \to X$, $p$ breaks up into $\tilde{X} \to E$ and $E \to X$. this is why it's also said to be "universal". now, let $\tilde{X} \to X$ and $\widehat{X} \to X$ be two different universal covers of $X$. by general nonsense, we get two morphisms between $\tilde{X}$ and $\widehat{X}$ pointing in different directions that exhibits each other as inverses in $Cov/X$

@BalarkaSen: I think you meant to send this 3 days ago.

that's what I meant when I said "unique"

I just recalled I didn't tell you about this, yeah.

@BalarkaSen: I'm doing something unrelated just now, I'll read and think about it in an hour or two.

besides, I am free after some time. got a buckload of exams to finish.

sure.

Nope, I mean $1$, @Owatch.

$\arctan(x) \cdot 1 = \arctan(x)$

uhhhhh

Okay. I went with $u = tan^{-1}x, du = -csc^{2}x, dv = dx, v = x$.

I can try again using that. (So far it worked okay this way).

@AlecTeal I think Oli deleted that room?

@Owatch $u = \arctan(x) \implies \text{ d}u = \dfrac{1}{1+x^2} \text{ d}x$

@skullpatrol it's frozen, why?

I can't find it @AlecTeal

@Huy what are you doing right now (mathwise)?

@Khallil I used a table which says the derivative of cot(x) (tan^-1x) is -csc^2x

@skullpatrol look at the channels ToolPurger is in (purple icon)

But I can do again.

@BalarkaSen: Going through basic proofs of diffgeo again because I have an exam coming up on Monday. I went over them too quickly last time and wasn't very satisfied, so I want to do better this time.

ah, I see.

Thanks pal @AlecTeal

@BalarkaSen: Very standard stuff, like the one I posted on main (coordinate basis is a basis of tangent spaces), or for example that every derivation at $p$ is a tangent vector at $p$.

What brings you here @GraceNote?

Is someone flagging?

@BalarkaSen: Oral exams usually start with questions about basic foundation stuff and last time I spent too much time on the more difficult stuff instead.

well, good luck with the revision.

Hi @GraceNote is it time already for my lifetime suspension?

@BalarkaSen: Are you done with your exams then or just taking a break right now?