Mathematics

robjohn

12:32 AM

@wj32 like as a paperweight, or doorstop. How did you want to use it?

Or did you want to read it?

Gustavo Bandeira

►

Peter Tamaroff

@robjohn ...lol....

Don't laugh. I'm drowning, actually.

robjohn

@PeterTamaroff Drowning?

Peter Tamaroff

@robjohn $$\Huge\text{.....lol......}$$

Doesn't it look like a guy drowning?

robjohn

@PeterTamaroff Ah! I see... yes it does.

Peter Tamaroff

12:45 AM

Anyways, I'm off to eat.

See you.

robjohn

@PeterTamaroff Good food!

anon

Useful fact: When people drown they don't put their hands up in the air or yell. They use all of their energy bobbing up and down for air.

3

Peter Tamaroff

1:39 AM

@anon Hhehee. Dude.

@anon Could you peer review this?

@robjohn Maybe you?

Qual Fighter

2:17 AM

Does anyone know what "sous-tore" means in French? Literally I think it's subtorus. Not sure if that's a thing

Peter Tamaroff

@QualFighter Some google revelas "sous" is also used as in "sub group".

Whatever "subtorus" means (IRW torus) might be relevant.

Qual Fighter

maybe i haven't been exposed to this kind of a torus before

i guess it's an algebraic torus or something

Peter Tamaroff

Note that sometimes langauges don't share literal translations

for example

Qual Fighter

peter, aren't you agreeing with my translation?

as a sub torus?

i know that sous-groupe or something like that is subgroup. so i got the meaning. maybe i'm just in need of math translation :)

Peter Tamaroff

In English, we call them "Fields" but in Spanish, we usually call them "Cuerpos" literally, "Bodies", and "Campos" (Literally "Fields") is not much used.

Qual Fighter

2:22 AM

corps = fields in french. i think corps means body

Peter Tamaroff

@QualFighter Yes.

@QualFighter But "corpse" is another thing, hehehe.

@anon

wj32

@robjohn Do you think it would be a good book for someone who has done some real analysis and algebra but no multivariable calculus?

Or will I end up not being able to compute the volume of simple objects?

Peter Tamaroff

@wj32 What is "it"?

wj32

@PeterTamaroff Calculus on Manifolds by Spivak

Peter Tamaroff

@wj32 They say that one is as though as Adamantium.

wj32

2:29 AM

Have you used it?

Peter Tamaroff

@wj32 Nope.

Peter Tamaroff

2:53 AM

@GustavoBandeira Bro.

Gustavo Bandeira

@PeterTamaroff Yo

What's up?

Peter Tamaroff

@GustavoBandeira Check this out

Gustavo Bandeira

@PeterTamaroff Soothsayer. =)

Maybe this is going to answer a question I had today.

Peter Tamaroff

@GustavoBandeira What does that mean?

Gustavo Bandeira

@PeterTamaroff Someone who predicts the future.

I'm reading the first pages of Limits today, until now, he gave me the definition of limit

Peter Tamaroff

3:05 AM

@GustavoBandeira You're reading what book?

Gustavo Bandeira

But I'm still with a naive definiton for it.

Paul's Notes and Stewart's Calculus essentials

Peter Tamaroff

@GustavoBandeira Hmmmm. Paul's Notes?

Gustavo Bandeira

tutorial.math.lamar.edu

Look: $$\lim_{x\rightarrow 2}(x^2)=4$$

And:

$$\lim_{x\rightarrow 2}(x^3)=8$$

I thought them similar to function evaluations.

Peter Tamaroff

@GustavoBandeira ?¿?¿?¿?

Gustavo Bandeira

$x^2=4$

and

$x^3=8$

It seems like "solve for 2"

BUT, as I said, still on the first pages.

First - actually.

brb

Peter Tamaroff

3:14 AM

gotta go

byes

robjohn

4:25 AM

@wj32 It is a good book. I don't remember the problem sets, but the exposition is good.

user19161

8:17 AM

It's quiet in here. The kids are still partying.

user19161

@PeterTamaroff Yes, I recommended him and Mohamed because I thought they would be helpful. But they are too simple for you!

Gustavo Bandeira

8:38 AM

@WillHunting I'm at home.

Chris's sister

9:03 AM

Hi. How may I find who downvotes me almost every day?

(downvotes on my questions)

user19161

@Chris'ssister I looked at your rep history. You don't have that many downvotes, except on a day when the serial downvotes were reversed. If you still feel this is a problem, you can raise a question on meta. But I suggest you wait a few more days to see how things go. Usually these people with nothing better to do will stop after a while.

Chris's sister

@WillHunting: I don't understand why is good to punish a good question. I don't see any logic in this.

meg_1997

Hey will anyone help me to solve this math.stackexchange.com/questions/196078/…

user19161

@meg_1997 I was just reading it. From the context of a mountain I can't imagine how it is done as described either yet.

user19161

@Chris'ssister Well, some people may genuinely feel it is not a good question. But we do not know what they think in their hearts. Anyway, don't worry too much about it!

meg_1997

9:16 AM

@WillHunting i did not understand the question itself:(

user19161

@meg_1997 Are those the exact words of the question?

meg_1997

@WillHunting ithink there might be some correction in the sentence formation

user19161

@meg_1997 Get the exact words first then. If those are the words then I think it is a bad question.

meg_1997

@will huntinghey i am so sorry i made an edit its 60 degrees

user19161

@meg_1997 I will post an answer shortly.

user19161

9:27 AM

@meg_1997 Oh, someone posted a pic already...

wj32

Question about sequences: If I define a sequence by $a_1=1$ and $a_{n+1}=\sqrt{1+a_n}$, it is easy to see that $a_n \rightarrow a$ for some $1<a<2$.

My question is: why must $a$ satisfy $a=\sqrt{1+a}$?

user19161

@wj32 If you know that the sequence converges, take limits on both sides of the equation. QED.

wj32

@WillHunting Ah! Thanks

user19161

@wj32 Great minds get stumbled by the most trivial things at times...

wj32

@WillHunting :(

user19161

9:34 AM

@wj32 Hey did you check my proof of the V or inverted V thing? I hope you know where I posted it in chat.

wj32

Yes, I did.

I'm pretty sure it works, but I'm reluctant to "accept" it, if you know what I mean...

user19161

Well, it's ugly in a way.

user19161

But I am not sure if there is a neat way to prove that lemma.

wj32

I guess the ugliness is just a consequence of the ordering of the real numbers - we have to check 2 cases all the time.

user19161

There might be some really nice combinatorial proof, I don't know.

wj32

9:37 AM

Yes, I wonder if that kind of thing is studied in combinatorics

user19161

In fact, I haven't really checked enough to make sure that the lemma and proof are indeed correct.

wj32

Given $x_1,\dots,x_n$ and a set of conditions, how many "completely specified orderings" of those numbers are there?

But this seems to be too general to attack for now

wj32

10:23 AM

What do you guys think about the following notation:

$f : (\mathbb{R} \rightarrow \mathbb{R}) \rightarrow \mathbb{R}$

$f(x \mapsto x^2) = \cdots$

peoplepower

10:46 AM

It is well-defined as long as you know the type of f.

And, of course, the formula must describe a valid $\Bbb{R}\to\Bbb{R}$ function.

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$Mathematics$ Mathematics