00:00 - 18:0018:00 - 00:00

12:01 AM
NO!
Is it okay to fix ugly TeX by coauthors?

12:44 AM
@JasonBourne You there, Jas?

user19161
@amWhy Yes, why?

@JasonBourne Just saw your gravatar, but not on the right...just checkin'. I need you ;-) - I want to take a break from math.se tonight...!

user19161
@amWhy Hmm, I am taking a long break from this site too.

@JasonBourne Yeah, I've seen that. Just need a break, or did something trigger your absence, or anticipated absence?

user19161
@amWhy Well, I just come and go as I please, like the wind. I am a free man!

12:49 AM
@JasonBourne Yes you are! 8-)

1:00 AM
@mick Do you mean find a sequence $\{a_n\}$ so that $$\pi^{-x}=\sum_{n=1}^\infty \frac{a_n}{n^x}$$

@JasonBourne Well, don't be a stranger...you can always email me. Reading anything good?

user19161
@amWhy No, I am not reading anything these days. I am in a bad state of mind.

@amWhy copy any good answers lately :-D

@robjohn - I'm both embarrassed and a bit "pissed off"...about the flag!
@robjohn I was just pinging you!

@amWhy new users get very protective about their points... don't fret

user19161
1:02 AM
@amWhy What flag was it?

Apparently, a new user thought I "copied" his/her answer, and I guess flagged a moderator. I tried to appease him/her by deleting my answer; it wasn't anything noteworthy to bother keeping...

user19161
@amWhy Ah, but what happened to make him think it was copying?

user19161

user19161
There are not many ways one can say that 1+1=2.

They were both similar...yeah, it was that sort of question; obvious approach...I was thinking of deleting my answer anyway, since my post followed his/hers, in timing.

1:07 AM
@amWhy It has happened to me, too. I usually do the same thing (delete mine)

@robjohn Certainly - nothing to fret about...:-)
@JasonBourne 2 = 1 + 1

user19161
If they are sufficiently distinct keep them.

user19161
If they are too similar, delete them.

@JasonBourne Yup...
@JasonBourne Yup...

parktime... bbl

user19161
1:09 AM
@robjohn Have fun with doggie!

yo i got a question about probability.
say i'm trying to estimate the probability that the product of two invertible matrices with finite order has finite order
with entries in {-1, 0, 1}
never mind actually.

2 hours later…
3:11 AM
@MarianoSuárez-Alvarez Hey
Is there a typo here?
0

I am doing Problem 5.10 of Marcus where it is given that $m$ is a square-free negative integer and that $\mathcal{O}_K$ is a PID where $K = \Bbb{Q}(\sqrt{m})$. Now in part (b) of this problem he asks: 5.10 (b): Suppose $p$ is an odd prime such that $m < 4p$. Show that $m$ is a non-s...

mfw MO comments have no edit window

3:57 AM
@Sanchez hey

@OldJohn I posted a p-adic question on MO you may have interest in.

@anon Man I can't believe
without the basics

ain't-nobody-got-time.jpeg

@anon huh?

@BenjaLim, hey

4:16 AM
@Sanchez hey
@Sanchez I can't believe my friends who have just taken a basic course in group theory
very very basic
want to learn category theory :D :D
For me, if you don't even understand the what the universal property of the quotient is
You are not fit to learn just yet what a derived functor is.
@WillJagy yo

Alright, yo. We'll go with that

@WillJagy I wonder why students nowadays are so impatient
Of course everyone wants to be Gordon Ramsay
but who can be one without first learning how to peel and slice a cucumber?

By and large, I think it is the effect of computers, calculators, and so on. They give support to anyone who feels it is not necessary to understand anything, or remember much either.

I agree.
@WillJagy If I see a student who hasn't even internalised the definition of a ring, that person is definitely not ready to learn about the Yoneda Lemma.

Well, there you go. There was a little while after World War II when science and mathematics were important in the US. But most of the population still didn't care. Now, computers have made significant inroads into mathematics education, so even the tiny population who would be doing mathematics are affected to some extent.
well, night

4:35 AM
Hi guys...
I require some help regarding the TeX
how to use teX for equations...
like say - you wanna show that this expression is eqn. (1)
Any help..?
someone here alive..? :P

@CrazyBuddy, use eqnarray?
or just \label, actually

a sample maybe good..?
coz I require it over Physics.SE ;-)
I'll see...

@CrazyBuddy, hmm, it doesn't seem to work here. What about just manually add (1), (2), (3)?

I tried that... - manual adding is a bit nasty ;-)

4:57 AM
never mind...
Anyway, thanks for responding.. Sanchez ;-)

2 hours later…
7:07 AM
hi everyone
could someone light me on this
i try to make logarithmic spiral
and following the formulas i found on wikipedia (or wolframalpha)
but r = a *exp(b*T) work
does i misunderstood the first formula ?

7:24 AM
@eephyne I guess it's better to ask in the main.

@mick used is the opposite of left
@mick and right is the opposite of wrong

I was thinking that was a little to "light" to be q main question
too*

@CrazyBuddy You can use \tag{1}
@CrazyBuddy or \label and \ref

@robjohn Yeah... I saw that already ;P
Anyway, thanks John :-)
Ohh... Rob John...

@CrazyBuddy sorry, I just saw \label I missed the rest

7:31 AM
No worries... I'm happy that some guys noticed it :P

7:48 AM
Morning everyone.
@robjohn Looks like I missed you yesterday. And I didn't get pinged, either, I only saw you replied because other messages pinged me and I clicked.

Hello everyone..

Hello.

I need help to brush up my maths..
specifically Linear recurrence relations
can somebody point me to good online material..
1st question.. is ther way or formula to find nth fibonisis number..? i mean when n is very large..
2nd how that is derived from f(n)=f(n-1)+f(n-2)

@knocker You could look at page 8. (bottom of)
bbl

Thanks man

8:03 AM
@MattN. hmm... how are you now?
@knocker $\displaystyle F_n=\frac{\left(\frac{1+\sqrt5}{2}\right)^n-\left(\frac{1-\sqrt5}{2}\right)^n}{\sqrt5}$

@robjohn hi

@BenjaLim hey there...

@robjohn It's australia day today

@BenjaLim what about Australia does that celebrate?
the date commemorates the arrival of the First Fleet at Sydney Cove, New South Wales in 1788 and the proclamation at that time of British sovereignty over the eastern seaboard of Australia (then known as New Holland)

8:18 AM
@robjohn Sometimes the celebration of australia day causes a lot of pain
last year the prime minister was swarmed by some demonstrators
@robjohn Not sure if the natives in america
@robjohn Sorry for deleting these I don't want to say anything politically incorrect in an online chatroom.

:7843010 There is never an end to such upset. Things get less inflamed, but they are not happy.

@robjohn They say there are three things one should never discuss: sex, politics and religiion

@BenjaLim yes. However, I don't think we've said anything controversial. Just factual so far.

:7843017 Now, that would be controversial...

8:25 AM
@robjohn that's why I deleted it

Here they combine the three in one discussion.

8:36 AM
@BenjaLim if i can't discuss sex, politics, or religion...then what are we going to talk about? ...math?!?

yes

let's try combining the subjects in pairs: do you think god is a mathematician? are the integers "hot"? are you going to vote algebraicially next election?

no the integers are not hot
whether god is a mathematician depends on your definition @DavidWheeler

my view on international policy: taking Obama mod 3, we see he is not prime. QED.
which definition: "god" or "mathematician"?

mathematician and god
btw @DavidWheeler
the definition of god
is not a well - defined definition

8:42 AM
well people certainly argue about its definition a lot.
the english word has a root meaning of something akin to "ultimate super-moral entity of goodness"...the existence of which is the contention of goedel's "proof of god"

@DavidWheeler what are you up to now

people being what they are, tend to anthropomorphize concepts....leading the the quaint image of '"some bearderd guy on a big chair in the clouds"
at this very moment i am in the process of trying to finish the repairs on my computer.
this video game i played burned up my old graphics card, so i got a new one, and a bigger PS
this ancient piece of 20-th century technology has a "grandmother board" at this point :(
trying to tickle better performance out of antiquated architecture is almost beyond my limits of technical comprehension of electrically thingymabobs

9:00 AM
@BenjaLim well, perhaps the first 68 integers are not...

@robjohn roflmaopmpzomgha!

@DavidWheeler that's what I get for coming into a conversation late. :-)
err... joining

@robjohn: hi

@Ilya hey there :-)

howdy

9:11 AM
@Ilya anything exciting going on today?

mmm
working on Saturday. exciting?

@Ilya on Saturday?

yes

@Ilya do you work on holidays as well?

depends

9:15 AM
@Ilya time to heat water for tea...

@robjohn: just do it! don't mind circumstances )
how is the weather?

@Ilya It is raining this weekend... but the storm is not as bad as predicted

@robjohn that's nice

@Ilya I'd like the rain. We really need it.

you don't seem to have is often there, do you?

9:21 AM
@Ilya Perhaps you didn't notice when you were here, but we are very dry here.
@Ilya not as much as other places.

@robjohn well, it was foggy

Hi folks, I have a question about mathematical writing.

@Ilya That's true. I forgot that that day was uncharacteristic.
@GarbageCollector Ooh... math. What are you doing here?

If we have to write algebraic operation steps, which one we have to use aligned in displayed mode or align*?
\documentclass{article}
\usepackage{amsmath}

\begin{document}
The following calculation is a trivial example
\begin{aligned} a(x+b)^2 - ab^2 &= a(x^2 + 2bx + b^2) - ab^2\\ &= ax^2 + 2abx + ab^2 - ab^2\\ &= ax^2 + 2abx \end{aligned}

The following calculation is a trivial example
\begin{align*}
a(x+b)^2 - ab^2 &= a(x^2 + 2bx + b^2) - ab^2\\
&= ax^2 + 2abx + ab^2 - ab^2\\
&= ax^2 + 2abx
\end{align*}

\end{document}
I am really confused.
I need conventionally adopted (by professional mathematicians) rules. :-)

@GarbageCollector here is something worth a look

9:30 AM
@robjohn OK. Thanks. I am reading...

@anon That looks interesting. I have found the tree idea for visualising p-adic distances really useful for $\mathbb{Z}_p$ and $\mathbb{Q}_p$, but my intuition for $C_p$ and $\Omega_p$ is really poor - so far so at the moment I don't have any ideas about differences for algebraic or transcendental elements . I find it curious that even on MO, p-adics questions don't seem to generate a lot of views.

@OldJohn I think that part of the reason is that on sci.math, there used to be a lot of cranks posting questions about p-adics.
@GarbageCollector I don't think that either has been generally deprecated. Use whatever works best for you.

@robjohn Ah - That is interesting. I never looked at sci.math, but heard there used to be a lot of argumentative stuff on there. We seem to be able to keep the cranks under control quite well on MSE :)

@OldJohn This is part of the reason I moved here from sci.math. I have never looked back.

@robjohn, how would you compare sci.math to here, or other math forums (say AoPS)? I heard about sci.math a long time ago but never really participate there.

9:38 AM
@robjohn I reckon that here, the nonsense seems to be limited to the chatroom, and away from the main site :)

@Sanchez It was very good when I was working at Apple (early to mid 90s), but after 2000 or so, it started a slow decline.
@OldJohn yes, the chatroom, while supposedly an interactive math forum, does play an important role of defusing the need to act out.

@robjohn, was it similar to mathoverflow now?

@Sanchez well, it was open to any level of question, so in that respect it was more like MSE... sci.math.research was more for advanced questions and discussions.

I see.

9:57 AM

@Ilya I have never tried.

I need to find a bibtex entry for one book from a reliable source

@Ilya for what?

Lindvall, Lectures on coupling method

@Ilya didn't find anything. Is everything spelled properly?

10:02 AM
maybe on THE coupling method
only
like here

I found the proper title...
@book {MR1180522,
AUTHOR = {Lindvall, Torgny},
TITLE = {Lectures on the coupling method},
SERIES = {Wiley Series in Probability and Mathematical Statistics:
Probability and Mathematical Statistics},
NOTE = {A Wiley-Interscience Publication},
PUBLISHER = {John Wiley \& Sons Inc.},
YEAR = {1992},
PAGES = {xiv+257},
ISBN = {0-471-54025-0},
MRCLASS = {60-01 (60J10 60K05 60K35)},
MRNUMBER = {1180522 (94c:60002)},
MRREVIEWER = {Uwe R{\"o}sler},
}

thanks!

10:23 AM
Coupling??
We do decoupling.
Is Ilya our inverse?
@Ilya Are you in your office?

no, fortunately I'm at least working from home
crafting a report for Frank

Good.
Happy to hear that Frank is of any help.

user19161
10:52 AM
OK, the new way of changing your picture now is working perfectly, no need to use gravatar anymore.

11:46 AM
@JasonBourne Hush.

12:39 PM
x
x*x
x*x*x
x*x*x*x
x*x*x*x*x

x^1 + x^2 + x^3 + x^4 + x^5+...

12:51 PM
Must a convex mapping be continuous on a convex set?

I receive parental pressure. My parents keep reminding me the sad truth that I am not so great at mathematics. They threaten that they'd cut my internet off if I don't qualify for the Brilliant.org camp. How do I cope with the pressure?

@FrankScience I don't know how to describe it exactly.

Ugh, that seems a problem set, and I think there's no serious problem if they cut off the Internet without which you can still study mathematics well.
Good luck.

1:09 PM
@robjohn Ok-ish, thank you. Slept with my neck twisted so that now I have a pain in the neck and a headache. What about you?

@MattN. Doing okay. There have been few questions that I've gotten to fast enough to answer. Too many flags keeping me busy.

1:22 PM
Hi everyone

user19161

1:48 PM
@JasonBourne answers are important, but the maintenance of the rest of the site is also.
@Novice why are your parents so determined that you go to brilliant.org camp?

How can I explain 0.9999... = 1?

@GarbageCollector ask what the difference of the two is.

If they were different, there'd be a number between them...

@GarbageCollector if the difference is $0$, they are the same.

@robjohn I don't know.

1:52 PM
$1-.9999=1/10^4$
$1-.99999999=1/10^8$

@robjohn But ... represents infinitely repeated.

Certainly we must have $0.999\ldots \leq 1$. Now, what happens if we add any $\epsilon > 0$ to $0.999\ldots$? We get something greater than $1$, so we must actually have equality in the inequality we started with. This is a standard technique for showing that two real numbers $a$ and $b$ are equal. if $|a-b| < \epsilon$ for all $\epsilon > 0$, then $a=b$.

for any positive difference, $\Delta$, you can find an $n$ so that $1/10^n\lt\Delta$

I have no idea how to explain it to my friends without using calculus.

@GarbageCollector they have to understand limits... without limits .99999... doesn't make sense

1:56 PM
@robjohn The book exercise just says: find 0.99999... in rational form. One method use the idea x=0.9999... and then 10x=9.9999.... You know the remaining.

One could also argue that $$0.999\ldots = \frac{9}{10} \sum_{n=0}^\infty \left(\frac{1}{10}\right)^n$$ and then use the formula for summing a geometric series. But that's just hiding what's really going on.

@kahen All of these arguments require knowledge of limits.

2:17 PM
@robjohn That is because they are parents. :-)

I hope I don't get downvoted on MO.....

2 hours later…
4:03 PM
hello to all

4:16 PM
@arber hello! Just happened by...
I'm having a slow day :-(

0
1-1
1+1-2
1+1+1-3

5:00 PM
Hello. I am the book of all answers.

5:29 PM
@MichaelGreinecker Did Ilya delete his question?

5:46 PM
Shall I expect Ethan to delete his question as well?

@Ilya Did you delete your question?

@JonasTeuwen no,why?

I try to find the one with the kernels.
What do you have to do when you think your neighbor is a homosexual?

nothing
unless you are interested in him of course

oh, Mariano was first :)

5:52 PM
Shall I go bring him some nuts and chips?
He was licking his lips when I was standing in the elevator with him.
While looking at me!
Looked kind of creepy and cool at the same time.

@JonasTeuwen just lips? huh!

are you that surprised someone might find you atractive?

am I correct, your tone suggests you think Jonas is attractive? @Mariano

suppose I have a boolean function $f$ which takes in some set $A$ and spits out a boolean value. And I have a set $A$ such that $f(X)= \text{true}$ for all $X \subseteq A$. Is there some formal term which will describe the relationship between A and $f$.

not my type, really :D

5:56 PM
and finally, somebody is in favor of 4's
@OrangeHarvester here $f(X)$ is the image of $X$, so simply $f(A) = \text{true}$?

00:00 - 18:0018:00 - 00:00