Mathematics - 2013-03-27 (page 3 of 4)

user19161

20:02

@HenningMakholm I wonder what a packet is there...

user19161

@robjohn Hehehehe.

amWhy

Does everyone realize that Caveman deleted his account? I know you explained why, most likely, Henning...but wow! What a dramatic reaction to a single post?

user19161

@amWhy I might too, soon...

amWhy

@JasperLoy Don't delete...if nothing else, for the sake of other users who you've supported!

user19161

@amWhy They might keep my votes like they did for Eng and TeX. Anyway, you don't need to worry about your humongous rep!

user19161

20:05

Even if you lose 20k, you still have 20k!

amWhy

@JasperLoy hehehehe...There may indeed be a way to close an account without a leaving a trace of one's presence.

Henning Makholm

@amWhy No, not everyone realizes that. For example I'm fairly sure that my mother doesn't.

user19161

@robjohn Some use mathbf instead.

user19161

@HenningMakholm LOL

Vrouvrou

hi

amWhy

20:09

@HenningMakholm hahahahahaha... Yes, you are correct...I would be in trouble if my"universe of discourse" were restricted to only math.se!

Vrouvrou

help me please

0

Q: Small question about a lemma of measurability

Hi ; I have this lemma , and i want to ask tow questions : 1) What is the diffrence between say that $\varphi$ is measurable and to say that $\varphi$ is $(\mathcal{T},\mathcal{B}(U))$measurable . 2)Why $\varphi_{p}(t,x) \rightarrow \varphi(t,x)$ when $p\rightarrow +\infty$. please, Help m...

robjohn

@JasperLoy Oh, that is not the $\mathbb{R}\text{eals}$!

user19161

@robjohn They are fake then! Like my boobs! =)))

4

Henning Makholm

@amWhy Even so restricted, this guy is most likely also a counterexample.

robjohn

@JasperLoy only the salespeople at Victoria Secret know...

amWhy

20:12

@HenningMakholm You got me, twice! ;-)

user19161

@robjohn I wonder what her secret is, hmm...

robjohn

@JasperLoy It's his secret :-)

Jayesh Badwaik

@JasperLoy There is a bug fix list which decides when the Debian will be released.

user19161

@JayeshBadwaik Yes, I know.

Jayesh Badwaik

@JasperLoy Ahh, so it seems by the look of it that it might be out this summer.

Dominic Michaelis

20:15

what is debian ?

user19161

@DominicMichaelis It is a GNU/Linux distribution, an operating system.

Jayesh Badwaik

the universal operating system

user19161

I consider it the best OS in the world.

Jayesh Badwaik

after arch that is? ;-)

user19161

Debian is BOSS!

Jayesh Badwaik

20:16

@JasperLoy BOSS?

user19161

Hey @jayesh you wanna keep your answer to my question?

Jayesh Badwaik

@JasperLoy Naah, might delete it soon.

user19161

Alex has rightfully deleted his!

Jorge Fernández

Is this kind of answer considered to be bad?? math.stackexchange.com/a/344092/33907

I feel sort of weird posting it.

Dominic Michaelis

hard to say just wait for up or downvotes

Jorge Fernández

20:22

I appreciate when people comment before up or downvoting

user19161

I downvote only very poorly written questions.

user19161

And when someone downvotes me I will downvote some bad answers to make my reputation a multiple of 5.

Dominic Michaelis

mh normally i don't comment on upvotes, but i always comment on downvotes

user19161

I have cast about 300 downvotes and 4000 upvotes, lol.

Jorge Fernández

thats a lot of both

although the balance makes you a nice guy

Dominic Michaelis

20:24

i cast 428 upvotes and 18 downvotes

user19161

I try to keep the ratio above 10.

Dominic Michaelis

who is that guy which hase more down than upvotes?

user19161

Did, Gone, Calvin Lin, Math Gems, YACP.

κρανίοπεριπολία

skullpatrol

:\

user19161

Anyway guys I was joking when I said I have fake boobs.

κρανίοπεριπολία

20:28

Too late ... I flagged it pal

user19161

Oh noes!

user19161

Yes, my pecs are real and quite polished...

robjohn

@JasperLoy I know one, but I wouldn't be surprised at another

κρανίοπεριπολία

>8(

user19161

(removed)

κρανίοπεριπολία

20:31

The mod is here ;)

gotta show some respect

& fear

Dominic Michaelis

& love

Jorge Fernández

how can i see?

Dominic Michaelis

you can't see love

κρανίοπεριπολία

open your heart

Bye Jasper

Dominic Michaelis

20:52

@robjohn why does the close votes not scale with reputation but the flags do

pourjour

21:17

hi

κρανίοπεριπολία

hi

pourjour

@κρανίοπεριπολία how are u skull

κρανίοπεριπολία

Fine thanks. How are you?

pourjour

@κρανίοπεριπολία pretty good

any news

κρανίοπεριπολία

I think we lost caveman :(

Dominic Michaelis

21:22

but who will teach me category theory ?

κρανίοπεριπολία

yourself?

pourjour

@κρανίοπεριπολία how?

κρανίοπεριπολία

Reading.

pourjour

@κρανίοπεριπολία just struggling with exams trying to survive

Dominic Michaelis

@skullie bu i won't answer any question i can't solve

κρανίοπεριπολία

21:26

@pourjour Everybody is struggling...

@DominicMichaelis You learn a lot from just trying...

3

IMO^^

pourjour

is there any ressource for the manner used here (determinant and modulo)

0

Q: Elementary Number Theory.. If a divides..

If $a \mid (2c+3d)$ and if $-a \mid (c+d)$ then show that $3a \mid 3c$. The only progress I can say I've made is that the question is basically asking to show that $a \mid c$, because the $3$ is only a constant.

number-theory elementary-number-theory

@κρανίοπεριπολία yeah this is life :(

κρανίοπεριπολία

@MichaelCorleone the one you understand the most.

Michael Corleone

What should I do here? Both Andreas Blass and Brian M. Scott answered at the same time with an answer that was useful. Whose answer should I accept? math.stackexchange.com/questions/344105/…

user19161

@MichaelCorleone Whichever you like.

Henning Makholm

@MichaelCorleone Flip a coin. If, upon seeing the outcome of the coin flip, you feel disappointed, then do the opposite of what it says.

3

Michael Corleone

21:31

@HenningMakholm Haha

κρανίοπεριπολία

...it really depends on how much you understand the answer.

Henning Makholm

I'm serious, actually. Accepting something to show that you consider your problem solved is more important than apportioning the rewards with exact fairness.

κρανίοπεριπολία

Remember that it is you that consider the problem solved.

Does it make sense to you?

robjohn

@DominicMichaelis what do you mean the flags scale with reputation? Do you mean the number that someone can cast?

Dominic Michaelis

yeah

robjohn

21:37

@DominicMichaelis dunno. I'd have to search meta to see if there is a reason.

Dominic Michaelis

ah i will just ask a new meta question or ?

robjohn

@DominicMichaelis Perhaps because close votes actually have an effect and flags are simply notifications to moderators? Not sure

Henning Makholm

@DominicMichaelis Better search meta first. It doesn't take special moderator powers to do.

robjohn

@HenningMakholm very good suggestion :-)

Dominic Michaelis

@Henning i already searched once but didn't found something

Henning Makholm

21:40

But since the rules are the same across the entire SE network, perhaps meta.SO would be more likely than meta.MSE to contain the reasoning somewhere.

robjohn

@DominicMichaelis there was a recent discussion, there should be something on meta

@HenningMakholm that is probably where I saw it

pourjour

any help with this:

$lcm[(n+1)(2n+1), n(2n+1)]$

robjohn

@pourjour other than $2n+1$?

Henning Makholm

@pourjour You can factor $2n+1$ out, obviously.

Then there's lcm(n,n+1) left, which is just n(n+1).

κρανίοπεριπολία

There should be a "Meta meta" to coordinate the meta's :-D

Henning Makholm

21:42

(assuming $n \ge 1$).

Dominic Michaelis

@robjohn in the review section

when you look at a duplicate the LaTeX is not rendered is that intentional ?

Henning Makholm

@DominicMichaelis There was a meta question about that recently.

robjohn

@DominicMichaelis Did you try the "render MathJax" bookmark?

pourjour

@robjohn no it's like I've written it

robjohn

@pourjour I was trying to say that was the $\mathrm{lcm}$ as Henning showed.

Peter Tamaroff

21:44

@robjohn What's up?

Dominic Michaelis

you mean that one ? meta.math.stackexchange.com/questions/3055/…

pourjour

ok

Peter Tamaroff

I went to a library to buy Apostol's Mathematical Analysis (used): 60 bucks.

Soft cover edition, but the pages are those glossy good ones.

I'm thinking about buying it.

Henning Makholm

@robjohn 2n+1 is the gcd, not the lcm.

pourjour

@HenningMakholm no I think lcm is (2n+1)(n+1)n

Jonas Teuwen

21:47

Il faut oublier.

Henning Makholm

@pourjour No what? I agree.

Jonas Teuwen

Tout peut s'oublier.

robjohn

@DominicMichaelis Oh, I see what you are talking about. There are problems when trying to render pieces of LaTeX from posts, and I think this is one of those cases. I usually just open the other question so that I can inspect more closely.

Jonas Teuwen

No? No? No? What! What?! I agree.

robjohn

@HenningMakholm Ah, yes.

Henning Makholm

21:48

@DominicMichaelis Actually, I remembered this one, but yours is better. It doesn't seem to have received any attention...

robjohn

@HenningMakholm Sorry, I am participating in too many conversations at once :-)

pourjour

@HenningMakholm ok so how can u correct it

robjohn

@HenningMakholm That's the one I was thinking of, as well.

Henning Makholm

@pourjour Correct what? I agree with you that your lcm is (2n+1)(n+1)n.

robjohn

@PeterTamaroff Lots of meta, comment wars, and chat :-)

Peter Tamaroff

21:49

@robjohn Feed me the news! What happened?

pourjour

@HenningMakholm yeah I found in another way can you show another manner to do that

Henning Makholm

@PeterTamaroff People leaving in huffs. Stop the presses!

robjohn

@PeterTamaroff I've answered a few questions, but last I checked, not votes. :-(

Henning Makholm

@pourjour Your 'yo' key seems to be broken.

Peter Tamaroff

@HenningMakholm LAWL

pourjour

21:50

@HenningMakholm sorry

Peter Tamaroff

@robjohn I got to 20k! Kapow!

Henning Makholm

@PeterTamaroff CONGLATURATION

Peter Tamaroff

@HenningMakholm Last thing I heard is Chrissisterandpals ragequited.

Dominic Michaelis

congratulations

@peter again ?

Peter Tamaroff

@DominicMichaelis Well, no. He/she just ragequited from main.

Henning Makholm

21:52

@PeterTamaroff Oh, I didn't hear about that. But 'caveman' left suddenly this afternoon.

Peter Tamaroff

@HenningMakholm Odd. Did someone wave a fire at him? Might have scared him.

robjohn

@PeterTamaroff You were 95 short yesterday :-)

Peter Tamaroff

@robjohn Yeah.

robjohn

@PeterTamaroff Congratulations!

Peter Tamaroff

@robjohn Did you see my answer on Heine Cantor?

robjohn

21:53

@PeterTamaroff nope. I've not had time to even write the answers I want to.

Henning Makholm

@PeterTamaroff It seems to have been due to the disputes over deleted answers here. Also briefly spilled into chat; see the double-starred comment by anon.

Peter Tamaroff

@robjohn Oh, bummer.

Jonas Teuwen

Let's kick some ass.

Peter Tamaroff

@HenningMakholm Oh, I see. I answered a question using Group Theory basics, and caveman critiqued it, and decided to give a "simple" answer.

Seems anon defended the Algebra like a true Algebraist!

robjohn

@PeterTamaroff which question?

Peter Tamaroff

21:56

@robjohn This one

This is the Heine Cantor one

robjohn

@PeterTamaroff Too algebraic :-) what does $|a^r|=|a|\iff (r,|a|)$ mean?

Peter Tamaroff

@robjohn There is an $=1$ missing.

I added it.

I did write it in the next sentence though.

robjohn

@PeterTamaroff That's what I thought, but I could also have just been confused.

Dominic Michaelis

i am like

robjohn

@PeterTamaroff I saw that, but there were points instead of absolute values, so I wasn't sure

Peter Tamaroff

21:59

Damn. Caveman really did quit.

Karl's students

@JasperLoy: The popularity of PSTricks is decreasing as the time goes.... google.com/trends/…

Peter Tamaroff

@robjohn Points?

robjohn

@PeterTamaroff He did. Do you know why?

@PeterTamaroff $\langle\dots\rangle$

Peter Tamaroff

@robjohn Probably because of criticism. Kinda weakish! =/

@robjohn I don't understand? I wrote $\langle a\rangle$, not $\langle \dots \rangle$

robjohn

@PeterTamaroff yeah. Someone mentioned something like that on meta

Michael Corleone

22:01

@κρανίοπεριπολία Sorry for the late answer but both answers made sense to me

Peter Tamaroff

@MichaelCorleone If some Caveman comes asking you to do him a classic Godfather favour, please refuse.

robjohn

@PeterTamaroff $\langle\dots\rangle$ was demonstrating points, not what you wrote

Michael Corleone

@PeterTamaroff :).

Henning Makholm

@PeterTamaroff Remember that turnover isn't always bad. Some quits are net wins.

Peter Tamaroff

@robjohn Could you take a screenshot? I don't understand... =/

robjohn

22:02

@PeterTamaroff like $|\dots|$ is absolute value

Peter Tamaroff

@robjohn Well, it is order of the element in this case.

Do you use $o(a)$ instead?

I don't like it.

@HenningMakholm Hmmm. The guy did share some nice stuff, though.

@HenningMakholm Do you like my answer?

robjohn

Henning Makholm

@PeterTamaroff Where?

Peter Tamaroff

@HenningMakholm here

κρανίοπεριπολία

@MichaelCorleone What I'm saying is does one answer seem to be more "basic" than the other?

Peter Tamaroff

22:04

@robjohn OK, so?

robjohn

@PeterTamaroff There are $|\dots|$ on the left and $\langle\dots\rangle$ on the right. I didn't know if that had something to do with the lack of the $=1$ on the left

Peter Tamaroff

@robjohn Oh, I see.

WhitAngl

Hi, there used to be a PavelM on math.stackexchange (now "user53153") that I'd like to acknowledge, but he seems to have disappeared. Anyone knows his name and/or contact ?

Henning Makholm

@PeterTamaroff I would share Robjohn's confusion if I hadn't just seen your explanation.

Peter Tamaroff

$\langle a\rangle$ denotes the (cyclic) subgroup generated by $a\in G$. In particular, the order of $\langle a\rangle$ is equal to the order of $a$. Since the groups are finite, the left part is the same as the right part.

Henning Makholm

22:06

This may call for an explicit explanation such as "where (notation) means the order of $a$".

Peter Tamaroff

@HenningMakholm Yes, you're right.

κρανίοπεριπολία

He is rarely mistaken.

Peter Tamaroff

@HenningMakholm I edited.

robjohn

@PeterTamaroff You can't get points for suggested edits any more. I think that up until 20K edits to tag wiki are suggested

Henning Makholm

I also think stating the definition of "primitive root" explicitly (given that the OP didn't bother to) might be helpful. -- I intuitively tend to think of "primitive roots" simply as e^{2\pik/n} where k is coprime ...

robjohn

22:11

@PeterTamaroff I think I got 20-40% of my suggested edit credit between 10 and 20K

Peter Tamaroff

@HenningMakholm I see.

robjohn

@HenningMakholm That's what I would assume

WhitAngl

any one knows PavelM ? :s

Dominic Michaelis

the project euler questions shouldn't be on this page why is there a project euler tag ?

Peter Tamaroff

@WhitAngl Nope, sorry.

Henning Makholm

22:13

I'd also write the "\iff"s out in words, because the equivalences are part of your logical argument, rather than a formula you're arguing about.

κρανίοπεριπολία

:)

WhitAngl

:s ok. He seemed to have a rather high reputation but his account has been removed apparently. I'll repost the question later in case someone comes. (or any other idea to get his identity?)

Peter Tamaroff

@HenningMakholm Is that standard agreement? That is, words versus symbols in proofs?

Dominic Michaelis

@charlie huhu

Henning Makholm

@DominicMichaelis The times it has been discussed on meta, there hasn't been any solid consensus to wither forbid or welcome these questions. Tagging them is the next best thing, which nobody objects to.

Charlie

22:14

@DominicMichaelis hello

@κρανίοπεριπολία Hello

Peter Tamaroff

@WhitAngl I just do it out of lazyness. =P

Dominic Michaelis

oh ok, but i will go sleeping now

good night

Charlie

@DominicMichaelis Good night! Gute nacht

κρανίοπεριπολία

@Charlie Hello, how are you?

Charlie

@κρανίοπεριπολία I'm fine, and you? :P

κρανίοπεριπολία

22:15

@Charlie Fine thanks.

Charlie

@κρανίοπεριπολία Great!

WhitAngl

@Pe

robjohn

@PeterTamaroff: Finally, I know :-)

Henning Makholm

@PeterTamaroff I could say yes, but it's possible that it's more of a personal preference. I feel proofs are easier to understand when the logical structure of the proof itself is written out in words. Using symbols looks like you're asking me to consider this-or-that formal object.

WhitAngl

@PeterTamaroff what do you mean ?

κρανίοπεριπολία

22:16

@Charlie I haven't seen you for awhile?

Charlie

@κρανίοπεριπολία yes! it's been a long ago...

Peter Tamaroff

@robjohn Hehe.

κρανίοπεριπολία

It's been a long time since I Rock n Rolled

►

Ethan

can anyone familear with the dirichlet hyperbola method help me here

pourjour

22:31

is there such a way to find GCD using congruence system

Ethan

what do you mean

pourjour

this

millersville.edu/~bikenaga/number-theory/systems-of-congruences/…

Ethan

@pourjour you could try to find the minima over the two varriable diophantine equation $ax+by$ in x and y using modular arithmetic, this should be the gcd(a,b)

pourjour

to be clearer

0

Q: Elementary Number Theory.. If a divides..

If $a \mid (2c+3d)$ and if $-a \mid (c+d)$ then show that $3a \mid 3c$. The only progress I can say I've made is that the question is basically asking to show that $a \mid c$, because the $3$ is only a constant.

number-theory elementary-number-theory

I find this

now I'm looking for reference for cramer's rule

Ethan

@pourjour it might be simpler when doing dividisibility questions like that to write them out using modular arithmetic so instead of $a\mid b$ write $b\equiv 0$ mod $a$

this way all the simple tools youve proved that apply to modular arithmetic

can now be used on your other problem

pourjour

22:38

ok here is an example

Henning Makholm

I just noticed the irony that the first question ever where I've actually responded "tl;dr" is entitled "Very quick question related to blah blah blah".

Peter Tamaroff

Chudnovsky is da bawz $${1 \over \pi } = 12\sum\limits_{k = 0}^\infty {{{{{\left( { - 1} \right)}^k}\left( {6k} \right)!\left( {13591409 + 545140134k} \right)} \over {\left( {3k} \right)!{{\left( {k!} \right)}^3}{{640320}^{3k + 3/2}}}}} $$

Ethan

@Peter Tamaroff didn't the chudnovsky brothers both come up with it

Peter Tamaroff

@Ethan I never said they didn't.

Henning Makholm

Hmm, does this count as a duplicate of the Batman question or not?

Peter Tamaroff

22:48

@HenningMakholm Oh, please mark it as a dupe.

user19161

I just edited my 4 questions for some minor reasons. Now I am done with editing my questions. Moving on to answers next.

pourjour

@Ethan math.stackexchange.com/questions/296987/…

Charlie

@jasper HIII!

user19161

Note that one can edit at most 5 old posts a day, so this should not cause too much disturbance via bumping.

pourjour

do you know any ressource where can I learn the cramer's rule and modular

?

user19161

22:49

@Charlie Hey hey.

Charlie

@JasperLoy :D

κρανίοπεριπολία

>8(

Charlie

@κρανίοπεριπολία oh what happened?

κρανίοπεριπολία

Nothing, that's my mean square impersonation.

Charlie

hahaha

@Cтарый Джон Hi!

κρανίοπεριπολία

22:51

Hi @CтарыйДжон how are you?

Cтарый Джон

@κρανίοπεριπολία Hi! - Fine here, thanks - how are you?

pourjour

@CтарыйДжон how are you?

κρανίοπεριπολία

@CтарыйДжон Fine thanks.

pourjour

long time no see

Ethan

@pourjour do you need help with anything?

pourjour

22:53

@Ethan yes math.stackexchange.com/questions/296987/…

here someone used cramer's rule

I need a lesson in how to use in such cases

Cтарый Джон

@pourjour assalaamu alaykum

Ethan

You want me to explain to you how math gems gave his answer?

pourjour

@CтарыйДжон 3alaykom ossalam warahmato allah

@Ethan yes

Ethan

@pourjour Sorry, I don't understand his answer either, I could give you a different answer, but I am not really that familear with linear algebra, you should just post a comment asking him what he did or what you don't understand

user19161

@CтарыйДжон I thought only Muslims can say it.

Cтарый Джон

22:56

@JasperLoy I have Iranian friends who are not muslims who also say it ... but also, how do you know I am not a muslim?

user19161

@CтарыйДжон Just guessing there, and making small talk.

Cтарый Джон

@JasperLoy no problem :)

user19161

@CтарыйДжон But now that we are at it, are you Muslim?

Ethan

@pourjour Wait no I have it pourjour

@pourjour here one sec let me show you what he did

Cтарый Джон

@JasperLoy Aha! - that will be my secret :)

pourjour

22:57

@Ethan ok

user19161

@CтарыйДжон Sure, just like I have many secrets!

Cтарый Джон

@JasperLoy Indeed!

user19161

@CтарыйДжон Have I told you my beliefs about the God in Islam, Christianity and Judaism?

Charlie

@JasperLoy yes yes yes

Peter Tamaroff

@JasperLoy Nobody cares!

user19161

22:59

I believe this God exists, but he did not create the universe.

Cтарый Джон

@JasperLoy You have told me about your beliefs in Buddhist texts - not sure about the other religions

Transcript for

$Mathematics$ Mathematics