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00:00
well at least not in number theory
we're still trying to find that odd perfect number (or show that it doesn't exist)
I know. That makes the hunger for more results stronger... It is like you want your favorite candy, it is so within reach... then you can finally grab it.
Then it tastes much better right?
And if you have a hangover it is actually the best ever tasted.
The hangover is the analogy for the failure.
Holy cow, I am producing so much nonsense this evening! Even more than last week.
@JonasTeuwen yes i remember research. once i was given a project by my undergrad research advisor. i spent months showing a result only to find i had been scooped.
Is @robjohn integrating for some candies? Add some exponential decay and derive...
@Eugene Excellent. That's how it should be most of the time! 8-).
@JonasTeuwen preferably without the scooping. i was scooped twice already.
Lovely. I would do that to my students too. If they are still there that means they can be good mathematicians! 8-).
00:04
@JonasTeuwen that's generally not a good thing to do to your students
If they quit it means that they are not suited.
i was scooped by other professors
@Eugene That must suck man 8-).
@JonasTeuwen it does. not as bad as my friend though. he worked for a year then was scooped by heath brown
@Eugene Oh?
That must have sucked bigtime! 8-).
00:10
@JonasTeuwen yes. the problem is once heath-brown scoops you the damage is pretty irreparable
at least i had a chance to extend my results
i heard nash used to lie in wait to scoop phd students just as they were about to finish
So why did he get Scooped?
Oh yea, Nash.
@JonasTeuwen that's the punishment you get when you work on an active area of research. you compete with people a lot more experienced than you
@Eugene I know. I heard the same thing on this conference 8-). "He solved my problem in much greater generality...".
@JonasTeuwen yes. that's usually the case.
ugh. who uses additive notation for not-necessarily-commutative things?
00:15
@Eugene Being scooped by Nash must be really cool...
so either work on an obscure problem or work really fast
@Eugene I try both.
@JonasTeuwen i doubt it. 5 years of work gone down the drain?
@Eugene Haha, excellent. Would be perfect! A perfect proof futility.
@JonasTeuwen haha. oh well i prefer the good old fashioned useful phd.
@JonasTeuwen maybe you could accidentally leak your results to a competing researcher. would achieve the same effect.
00:20
Want to discover something new, do want want to get scooped by Nash? Why not Study Euclidian Geometry!?
;)
then you've already been scooped by Euclid
2
@anon but then you won't be scooped by nash right?
heh
plus it might be a greater honor than being scooped by nash. ;)
he's 84
@Eugene Wikipedia is your friend =)
00:24
in fact serre is older
Most people winning the Abel Price is older.
in fact the thing about serre is that he never scooped anybody. the things he was working on, nobody even thought to try.
Winning the Abel Price seems to be a combination of being a great mathematicican and being well over 70.
@N3buchadnezzar gromov was 65 when he won it.
00:52
@N3buchadnezzar Or your name start with P and you are from Israel.
@Eugene I'll try that, thanks!
@JonasTeuwen lol.
01:24
Hi
 
1 hour later…
02:54
Anyone around?
@anon
@robjohn
@JM ?
oh hi
@anon How's it going?
pretty good
@anon I'm having a problem with a theorem in Algebra
02:58
THEOREM 1.21 Let $H$ be a lineal homogeneous sistem of $n$ equations and $m$ unknowns, then if $n<m$, there exists $X \in K^m, X\neq 0$, which is a solution of the system.
Shouldn't it be $n>m$?
If there are more unknowns than equations shouldn't that be a problem?
Or is it because the sistem is homogeneous?
no, more unknowns means less-determined and hence more possibility
eg one equation in two unknowns
of course uniqueness would be an issue
@anon Right. Maybe I was thinking about that, then. Moving on... =)
I guess now algebra gets more interesting
knowing about Groups, Rings, Fields and Vector Spaces
we can view a lin homog system of n equations and m unknowns as a way to say that m vectors in K^n are linearly de-pendent
@anon Yes, that was expected.
The author introduces linear systems as the equivalents of finding a subspace of $V$, and as a way to find a system of generators of a subspace.
It is interesting from that point of view. I had no motivation before!
whoever named 'upper' and 'lower' central series must have been upside-down while doing math
03:06
"lin homog" abbrevation sounded very exotic stuff to me until i realized it is linear homogenous.@anon
heh, I'm just being lazy
@anon What are those?
@RajeshD I usually write LHS ehehhee
group theory
or in spanish SLH
seriously, the lattice of subgroups should tell us that bigger subgroups are "higher" than smaller ones. yet the upper cs starts at the bottom and the lower cs starts at the top.
03:10
@anon "More is less, and less is more". - Eddie Vedder.
@PeterTamaroff you're familiar with the allusion I take it?
@anon Hhehe yes.
Due to my limited math knowledge, I am rather used to not knowing most of the terminology here, and so when i saw that i thought its one of them, but after a moment when i figured out, Oh! man even i understand this.
"Up is down." - Captain Jack Sparrow
Hhehe
@anon When I finish algebra I'll get into Rudin and Apostol's chapter on Abelian Groups (In AnNumTh)
03:13
a chapter on groups in an analysis text?
Meanwhile, you're alone on that one.
@anon Yeah, mostly about cyclotomic groups, roots of unity, as far as I've scanned,
I have groupprops to help, but it's not complete
heh, cyclotomic group isn't a real phrase :)
@anon sub?
Sorry I mean cyclic
and (sub)group
there are cyclotomic fields generated by roots of unity, and the roots themselves form cyclic groups. (the group of units forms another abelian group)
03:16
well. group of units in the ring Z/nZ is different I guess.
@anon How would you prove this one:
a^2+b^2=c^2
Let $G$ be a set of $n$th roots of a nonzero $z$. If $G$ is a group under multiplication, prove $G$ is the group of the $n$th roots of unity.
If it is a group under multiplication then it should be closed under mult, which can only happen with $\epsilon_ n$ right?
Only with z=1, yes.
you can prove this using polar form for the roots
@anon Right.
03:19
Does Apostol really use $\epsilon_n$? Everyone these days uses $\zeta_n$ for the roots.
@anon I just used it, but I don't see him use iether, since little importance is given to that group for he moves on to Characters right away, it seems.
those are fun
they get tricky in rep theory when the rep's dim is >1 tho...
You also know about representation theory?
- Analysis
- Number theory
- Group theory
- Rep theory
What else?
I know a little bit I guess.
everything else!
03:23
I'm looking forward to representation theory, I'm taking it next semester
Cool!
I'll go to bed early today. Byes
later
Agh! someone posted my comment as an answer and got 5 upvotes
04:00
Is my problem out of bounty now?
This question had a bounty worth +50 reputation from Frank Science that ended 14 mins ago; grace period ends in 23 hours

One or more of the answers is exemplary and worthy of an additional bounty.

I wonder whether there's a way to treat such equation.
Copied from the link.
131
Q: How does the bounty system work?

A. Rex What is a bounty? What is the "Featured" tab on the homepage? How can I search for questions that have a bounty attached? How do I start a bounty? When can I start a bounty? How long is the bounty period? How do I award a bounty? Can I award a bounty to my own answer? What happens if there's no ...

@Eugene Well, I've cloned the problem to MO.
Hello, everybody.
How to prove Stolz-Cesaro theorem through $o$-manipulation?
Really algebraic way, without consideration about $\epsilon$-$N$, or something else about the definition of limits.
04:20
IOW how to prove $f\sim g\implies \sum f\sim \sum g$..
What does the notation $\sum$ means? (and, what's IOW?)
IOW = in other words, $\sum_{k=1}^n f(k)$
$f\sim g$ as $n\to\infty$?
yes
Any other assumptions? for example, something is positive?
04:24
well, $f(k):=a_{k+1}-a_k$ and $g(k):=b_{k+1}-b_k$, so basically that $\sum g$ is strictly increasing and unbounded I guess
@FrankScience that's nice.
I wonder whether it is possible to manipulate them without $\epsilon$-$N$.
@FrankScience i don't know. i'm not sure how to approach this problem.
$f(n)\sim g(n)$ means $f(n)=g(n)+o(g(n))$.
If you can prove $\sum o(g)=o(\sum g)$, it's not much more work.
04:27
Well, your notation is ambiguous.
$\sum_{k=1}^n o(g(k))=o(\sum_{k=1}^n g(k))$ as $n\to\infty$?
Oh, $\epsilon$-$N$ is still necessary.
How to explain this formula?
$\sum_{k=1}^ng(k)=\sum_{k=1}^nO(f(k))$ means that there exists $M$ such that for all $(n,k):\;1\le k\le n$, $|g(k)|\le M|f(k)|$.
But I don't know how to explain such equation about $o$-notation.
it means if $u\in o(g)$ then $\sum u\in o(\sum g)$, where $\sum$ is an operator that takes $n\mapsto u(n)$ to $n\mapsto \sum_{k=1}^n u(k)$.
04:44
is anyone good with diophantines?
05:16
@anon Let's take another example.
@anon First, let's consider $o$-notation with the multi-variables, just as $O$ done.
For example
$$\sum_{k=1}^nO(kn)$$
That's an example from The Art of Computer Programming.
The $O(kn)$ of summand means a function $g(n,k)$ such that there exists $M$ where $|g(n,k)|\le Mkn$ holds for all $1\le k\le n$.
@anon Here?
yes I'm listening
So let's consider $$\sum_{k=1}^n o(f(n,k))$$ as $n\to\infty$
The $o(f(n,k))$ means a function $g(n,k)$ such that for all $\epsilon>0$, we have $|g(n,k)|\le\epsilon |f(n,k)|$ as $n\to\infty$. Am I right?
"for all $n$ greater than some $N$" is more precise than $n\to\infty$
$N$ not necessarily independent of $\epsilon$
Sorry, I must have lunch now.
I think $N$ must be $N_\epsilon$, even if it's a constant.
05:50
the number of views per question on stackoverflow is pretty pathetic
The $o(f(n,k))$ means a function $g(n,k)$ such that for all $\epsilon>0$, we have $|g(n,k)| \le \epsilon|f(n,k)|$ holds for all $1\le k\le n$ and $n\ge N_\epsilon$.
@anon Edited.
06:13
The main difference between $O$ and $o$ is whether the constant in $O$ or $o$ notation is related to the variables. For example, $1/(n-1)=O(1/n)$ as $n\to\infty$ means that there exists $M$ and $n_0$ such that $|1/(n-1)|\le M|1/n|$ holds for all $n>n_0$, where $n_0$ is somewhat unrelated to $M$, but $1/(n-1)=o(1)$ as $n\to\infty$ means that for all $\epsilon>0$, there exists $N_\epsilon$ such that $|1/(n-1)|\le \epsilon$ holds for all $n>N_\epsilon$.
@anon I have explained again.
Yes, I read it. I understand asymptotic notation. Are you asking me a question, or trying to straighten out your thoughts, or what exactly?
Is this still about the SC thm?
I only want to take SC as an example.
ah
I wonder a systematical way to deal with limits just like algebra but not calculus.
Because I find that L'Hospital's rule for $\infty/\infty$ at $x\to a$ is not easy to prove.
Just like proving SC.
And I find that most calculus books more often uses $o$-notation than $O$-notation, but I find out that $o$-notation is more hard to manipulate, or I have not got the clear idea of $o$-notation?
Notice that $\sum_{k=1}^nO(f(n,k))=O(\sum_{k=1}^n|f(n,k)|)$ is much easier than the one for $o$.
starcraft?
06:23
Stolz-C...
oh. that's not as fun
Cesaro
Ok, take it easy.
leo
leo
what exactly do you want to do?
learn a technique to manipulate $o$-notations.
Just like $O$-notations in Concrete Mathematics.
@FrankScience : Hello ..
06:29
@lyengar well
@FrankScience : Can you comment on the new version of my proof sir ?
7
Q: Proving a statement regarding a Diophantine equation

IyengarFINAL EDIT : Prove that if $p^z|n^2-1$ $$p^{x-z}(p^{z}-1)=\dfrac{ n^2-1}{p^z}-3$$ doesn't hold for any chosen values of $p,x,n$ and $z$. Here $p>3$ is an odd prime , $x=2y+z, \ \{\{x,y,z\}>0\} \in \mathbb{Z}$ . There $n$ is an even number. If the above statement is prove it will lea...

See Chat Rules, especially rule 3.
Ashhhhh sorry sir .. How to remove it sir?
leo
leo
just leave it
@lyengar Try to edit your recent post in chat.
06:34
Sir
but Edit is not there
I think it has expired..
But from now.. I will be very careful..
@lyengar Never mind. There's no side effect.
@FrankScience : Thank you for your kind words sir..
Do you think my proof makes some sense sir ?
By the way, is it polite repeating sir in chat in English-speaking country?
@lyengar Sorry, I'm poor at number theory.
oh ok sir..
Are you familiar with number theory?
06:37
@FrankScience : Yes sir, a bit...
but that proof is too elementary ...
it doesn't contain much of the number theory
@lyengar Well, I'll ask a question.
ok sir.. you are always welcome..
Also elementary.
Ok sir..
leo
leo
@FrankScience look at this:
06:45
@leo anon mentioned that if $f(n)\sim g(n)$, we have $\sum_{k=1}^n |f(n)|\sim \sum_{k=1}^n |g(n)|$.
@leo which is equivalent to $\sum_{k=1}^no(f(k))=o(\sum_{k=1}^nf(k))$. Is it easy to prove without $\epsilon-N$ definition?
@FrankScience i think you mean f(k) here.
@Eugene Yes, I was wrong.
@Eugene in the first one.
yes i know
@Eugene : Sir I know you are a number theorist, can you see my proof once sir ?
@lyengar I found that Number Theory is really hard.
06:51
oh..
@lyengar Please avoid using sir online. I've asked a person and he said that it's seldom used online, especially when you don't know the gender of whom you're talking to.
@FrankScience : But sir, I am just saying that out of respect.. I know the people whom I am talking with are men..., I have high gratitude towards everyone so I used that sir..
@lyengar I don't know whether there's some word instead.
Well, it's off-topic.
@FrankScience : Ok sir/madam .. Hows that sir/madam ?..
Now consider $s(\alpha,n,\nu)=\sum_{0\le k<n}\left([\{k\alpha\}<\nu]-\nu\right)$.
where $[P]$ is Iverson bracket.
$0\le \nu\le 1$.
06:57
Why cant we get a latex typing here sir ?
You mean that you cannot show LaTeX?
Sorry, I'm born in nonenglish-speaking country.
So I can't get a clear picture.
And some words are really inexact.
leo
leo
@FrankScience what do you speak?
@leo Chinese
leo
leo
I see
@FrankScience : Sir I meant that you have typed something between $...$ . But it doesn't come out neatly.. why cant we make it look as a equation ?
07:00
@lyengar Oh, I know.
As that appears in Math.SE?
@lyengar See ChatJax
我們為什麼不能使文字出現在聊天的方程?
leo
leo
@FrankScience have you tried induction there?
Well, maybe from Google Translation.
07:02
所以你能看到我的證明一旦先生嗎 ?
ha ha
Yes sir...
It's hard to understand
ha ha
sorry sir
I can't even understand a nano meter of it
@leo $\sum_{k=1}^n o(f(k))=o(\sum_{k=1}^nf(k))$ as $n\to\infty$. It's asymptotics, induction is useless.
@leo : Are you a number theorist sir?
@lyengar You meant that you can only see the LaTeX code but not the displayed equations. Am I right
07:05
Yes sir
exactly
leo
leo
@Iyengar no
@lyengar Well, ChatJax
I mean can you verify some elementary proof in number theory @leo
@lyengar You should bookmark something.
leo
leo
@Iyengar I don't like that very much. Sorry
07:06
oh ok never mind..
@FrankScience : Are you a professor in some university sir ?
@lyengar No, only a graduate from high-school
oh ok sir.... I am in need of securing some patron.. and learn mathematics... thats why I asked sir..
@lyengar Have you installed ChatJax successfully?
Yes sir..
leo
leo
@FrankScience how do you interpret the left hand side of $\sum_{k=1}^no(f(k))=o(\sum_{k=1}^nf(k))$
07:10
3 hours ago, by anon
it means if $u\in o(g)$ then $\sum u\in o(\sum g)$, where $\sum$ is an operator that takes $n\mapsto u(n)$ to $n\mapsto \sum_{k=1}^n u(k)$.
@leo It's illegal in asymptotics.
@leo I've just thought.
leo
leo
@FrankScience so????
@anon how can you post comments from the transcript in that way? Do you just paste the permalink and hit enter?
@leo Recently, I've interpreted $\sum_{k=1}^n O(f(n,k))$. It's big-oh, not little-oh.
$A\iff B\iff C$ is ambiguous, doesn't mean there isn't a conventional interpretation of it as $A\iff B$ and $B\iff C$ (in contexts that aren't pure logic anyway)
many illegal things are more and more legal :)
@leo yes
@leo Do you know $\sum_{k=1}^nO(f(n,k))$?
@lyengar Installed, and click the bookmark, you'll see all displayed equations.
leo
leo
07:14
@FrankScience a very little bit. I have dealt with that sort of things some time ago
@anon with the explanation in your comment linked $\sum$ makes sense in this context :-)
@leo The rigorous interpretation is the set $$\left\{\;\sum_{k=1}^ng(n,k)\;\bigg\vert\;|g(n,k)|\le M|f(n,k)|\hbox{ holds for some $M$ and over all $1\le k\le n$}\;\right\}$$
leo
leo
@FrankScience I see
to be clear, a set of functions of $n$
(rather than just numbers)
@leo But I can't find a similiar little-oh-notation for anon's
you mean an explicit set to designate $\sum o(g)$?
07:22
Exactly, no. You can see that, the similiar notation $\sum_{k=1}^no(g(k))$ doesn't fit your meaning.
I'm talking about the $\sum$ operator applied to the class of functions $o(g)$. you're perhaps being pedantic.
(and of course $o(g(k))=o(1)$ for fixed $k$, so it wouldn't fit my meaning though it is similar notation. but I'm not talking about that.)
So $\sum o(g)=o(\sum g)$ is not a result of $o(u)+o(v)=o(|u|+|v|)$.
nope.
And a $\epsilon$--$N$ proof is necessary, I think.
the number of terms is actually a function of $n$; such is not the case in the latter and so induction will not work (induction will only reach fixed numbers of summands)
Yes, I think so too. Or at least some basic $o$-machinery developed first with $\epsilon$-$N$s.
07:29
Yes
But we should build up enough rules.
I don't think only $\sum o(g)=o(\sum g)$ and something else like $o(u)+o(v)=o(|u|+|v|)$ is sufficient.
sufficient for what?
To manipulate asymptotics, without too much consideration of $\epsilon$--$N$, just like $O$-manipulation.
 
1 hour later…
08:47
Hey everyone
somebody help me with this
2
Q: building transformation matrix from spherical to cartesian coordinate system

testuserHow to arrive at the following from given $ x = r\sin \theta \cos \phi, y = r\sin \theta \sin \phi, z=r\cos\theta $ $$ \begin{bmatrix} A_x\\ A_y\\ A_z \end{bmatrix} = \begin{bmatrix} \sin \theta \cos \phi & \cos \theta \cos \phi & -\sin\phi\\ \sin \theta \sin \phi & \cos \th...

08:59
@testuser See Chat Rules, especially rule 3.
$\LaTeX$
@All, do any of you use Vi/Emacs. If yes which? I just want to know (out of curiosity) what mathematicians prefer to use
vim
Sorry, I'm not mathematician.
I'm only a graduate from high-school.
Mathematician && CS Theorist Don Knuth uses emacs.
emacs seems awfully popular
Have you read Knuth's codes?
09:14
No. Why?
The indent style is very pretty.
That sort of stuff is possible on vim as well...... especially with languages like Python
@Nunoxic If you had read such code, you could understand what I meant pretty.
For example. MMIX
that is really good indenting. very readable.
Are you reading Knuth's code?
Yes. But can't make sense of it.
For example, mmmix.w
So Literate Programing is so good.
10:22
Excellent.
11:06
@JonasTeuwen I never claimed that. But I guess that those MO threads I found will be much more useful than anything I would be able to tell you about that problem.
@MartinSleziak Yes, I know you never claimed that.
lol, a "mononomorphism." someone really doesn't want that morphism.
But I was trying to say that to describe the language you need some kind of metalanguage.
And if you see that metalanguage as a proper language you also need a metalanguage to describe that.
not a morphism, but injective
Jonas: that seems to be too philosophical for me.
I always had a feeling that metalanguage and language are sufficient to me.
But perhaps I have never felt the need to formalize metalanguage again in some way.
11:39
@MartinSleziak Oh, I don't want to philosophize this. I was just wondering: okay, then we have our language and our metalanguage, but how the son of a monkey do we formalize this? Then we need another metalanguage to describe this and that sucks. That's where I stopped 8-).
But there are a couple of things, you have your finite alphabet which I am fine with. But then you have your metalanguage to describe what you mean with "there exists" right? You have deduction rules, but you need some way to translate the result into something that does not look so scary. So then you use it to talk what the results mean you have. If it works this way I think I can understand how it goes.
I am not sure that looks scary to you.
$(\forall m)(\exists n) m=n+1$
For every $m$ there is an $n$ such that $m=n+1$.
Which of them is considered scary looking, the one with quantifiers and logical connective, or the natural language?
to describe wht yo mean with "there exists" - this is already about semantics
I would say that inference rules, proofs, languages are more about syntax.
But I am not very good in metamathematics - I am not sure I'd be able to help you with your questions.
12:10
Hi ... i posted a question. can somebody help me with it
Wow. It appeared in notices: dx.doi.org/10.1090/noti857
The same issue contains some response from Elsevier: dx.doi.org/10.1090/noti853
12:50
Mathematical logic?
13:49
Hello
14:03
@anon I have a question if you are willing
14:34
is anyone here good with modulo arithmetic?
What kind of modulo arithmetic?
I am trying to understand how to solve for m^2 congruent to -1 modulo 2k+1
I put a question on the main site but it feels like people pull numbers out of nowhere
I am trying to understand how to solve it

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