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7:00 PM
shows that he is interessted to help you.
@JayeshBadwaik well even if the question comes from there it is not directly related to it or ?
 
Hello
every body
can I ask a question?
why the positive-definiteness of a riemannian metric implies it is non-degeneracy?
 
@gulan certainly
 
@CтарыйДжон
thanks
 
but it is quite possible that there is nobody here who can help!
 
:(
 
7:05 PM
@gulan isn't a metric degenerated (or a pseudometric) when d(x,y)=0 for some x $\neq y$
 
yes it is right
 
when a metric is positiv definit it implies that $d(x,y)>0$ when $x\neq y$
 
@WhitAngl - were they they the same person as Leonid Kovalev? f course, I might be wrong ...
 
I saw a discussion on math.SE that concluded it wasn't the same person :s
 
@gulan i am still in the third semester and a not native speaker sorry if my thoughts are wrong
 
7:10 PM
like Leonid not posting about PDE's
 
Check [this](http://math.stackexchange.com/questions/348331/supset-proof-of-invertible-functions). Me and Cameron gave the same answer and yet....
Just wanted to bring to attention something happens a LOT. People are biased in favor of people with more rep.
 
@WhitAngl Ah - then I might be wrong :(
 
@GitGud jupp i noticed that one often too
 
Why isn't the link working properly?
 
7:12 PM
@GitGud true but not surprising probably. :-/
 
Wikipedia states the stuff in the picture.... doesn't that mean that the only eigenvector is 0? (i.e. all eigen vectors are zero)
 
no
 
By the way, I'm not fishing for votes, I'll be deleting my answer and there's nopoint in having two equal answers.
Just wanted to show you this.
 
drN
As an engineer I am trying to express entropies in terms of internal energies. Now I know that $\mathrm{d}S = \frac{\partial S_a}{\partial U_a} \mathrm{d}U_a + \frac{\partial S_b}{\partial U_b} \mathrm{d}U_b$. Here, $U, S$ are internal energy and entropy resply'. My question is, what is this expressing a change in a quantity in terms of partial differentials called? Euler's.... something... I dont remember the exact name!Any help?!
 
@GitGud to be honest in last time i profited from that te person with higher reputation gets the upvotes
 
7:14 PM
can a unit of a ring be its own inverse?
 
@DominicMichaelis I don't get what you mean: last time you profited from that the user to higher reputation gets the upvotes? What does that mean?
 
I just don't understand the part about 'If v is not all zeros, then v and Av will not be parallel.
 
@Raindrop If v is a non-zero vector, and v is not in the null space of A, then Av is a non-zero vector
 
like if I have $Z_3 = \{0,1,2\}$ can I say that $2$ is a unit with $2^{-1} = 2$ (since $4$ mod $3 = 1$)
 
7:15 PM
@Eric yep
 
@CтарыйДжон crap
 
@Raindrop You can draw vectors parallel to Av
 
@Eric is that not what you wanted?
 
so then 2 is a unit of $Z_3$ ?
 
@GitGud Well I have about 8,8 k reputation now and as i am still a very untergraduate student, it's more than the average answerer has for the questions i answer, and hence i get the most upvotes, and usually when someone accepts an answer, he accepts the one with the most upvotes
 
7:17 PM
if by unit, you mean invertible element, then yes
 
An "interesting" property might be if there is some vector v such that Av is some scaled version of v.
 
@CтарыйДжон no, i am trying to find an element of any ring that is not a zero divisor or a unit
 
So the matrix A, acting on the vector V, doesn't rotate it at all -- it just scales it by some factor!
 
@DominicMichaelis I see, that's true too.
 
@Eric but some rings might not have anything other than zero divisors or units
 
7:19 PM
I don't know if my answers improved a lot in the last 47 days but now i get usually at least 2 upvotes per answer
when i started it was most times something about 0 or 1 upvote
 
@CтарыйДжон yeah, like $Z_n$ or $Z_n \oplus Z_n$ (which i literally just discovered)
 
@DominicMichaelis They have improved a lot. I remember at the beginning your answers were awful. Despite being correct, they weren't helpful at all.
 
@Eric here is a nice exercise: Show that in a finite ring, all elements are either invertible or 0-divisors
 
@Eric yep - although I am not the right person to ask - I know almost nothing about algebra
 
@Eric so you need to consider an infinite ring to find something that is neither
 
7:22 PM
discussing reputation, upvotes, downvotes is a waste of time
 
@GitGud nice to hear that they improved, if you have some advice what I can do better feel free to say so :)
 
hint: There are infinite rings with no non-zero 0-divisors which contain non-zero non-invertible elements
 
@DominicMichaelis I think you are very clear now. And math-wise you know much more than me anyway...
 
I think Eric was originally looking to show every ring had a nonunit nonzerodivisor.
 
@TobiasKildetoft yeah i was getting that feeling, but i just found an example, a matix in $M_2(Z)$
 
7:24 PM
@Eric you could also just take the integers.
 
@Expert no, sorry i was a little vauge, i meant an element of any one specific ring that is not a zero divisor or a unit
 
@GitGud I don't think so it's my second year in university now I need to learn so much more :(
 
@Eric consider 2 in the integers
 
@TobiasKildetoft oh crap.. yeah, duh
 
@Expert What is your area of expertise?
 
7:31 PM
just read through the tags on my profile I guess
(they are weighted unevenly by popularity though)
 
@Expert That's why I asked you directly :-)
 
how is it possible to contact moderators ? I don't see any private messaging option in user's profiles..
@mixedmath
 
@κρανίοπεριπολία Congrats
 
@Arkamis What happened?
 
@WhitAngl If you want to communicate with moderators in general, flag a random posting and use the "other" option to write a free-form message.
 
7:42 PM
lol ;)
@HenningMakholm is it appropriate to do that ? ;)
 
@κρανίοπεριπολία You have a real QB!
 
@WhitAngl Sure, it's what they usually recommend in meta threads.
 
ok thanks then :) !
 
Matt Flynn!
 
7:44 PM
No, Wow!
cool
 
@DominicMichaelis SURELY you must be joking ! 1) the functions are defined by iteration hence the tag DYNAMICAL SYSTEM is logical. Second The infinite sum converges TRIVIALLY so I did not explain it. Third the formatting is not perfect but acceptable. Fourth MOTIVATION IS SUBJECTIVE and NOT part of the answer. BESIDES im am not pissed at Did. I just think its not so helpful , it has never helped before , if the source mattered alot I would have mentioned it anyway.
 
Yeah, he's solid
 
yesterday they told me I should post it formally , I did today and now its about motivation ? running in circles ...
 
7:46 PM
@Expert What do you think of Matt Flynn going to the Raiders?
 
have no idea who that is
 
@Expert What do you know?
 
@mick your question is poorly written and looks like a bunch of random shit that comes out of nowhere.
 
@Expert Do you even know who the raiders are?
 
@mick If you provide motivation (where did the question come from), it might spawn some ideas as to why those terms appear how they do
 
7:49 PM
take it down a notch ark, please
 
Until you do that, it looks like a bunch of shit thrown together.
3
Unfortunately, we go over this time and time and time again with your questions.
 
@Expert Who are you to come in here and tell someone to "take it down a notch"?
 
that's why I rephrased it as a request.
 
@arkamis i think the same
 
@Expert Who are you?
 
7:52 PM
oh please, lovebird #1.
2
 
@Arkamis but that is the answer you must give , why do the equation ( terms ) hold or turn up as they do ??
 
@mick The importance of motivation is precisely why, say, OEIS exists. If you find some collection of terms, perhaps some underlying links can be discovered between other theories that might lead to a proof.
@mick No. The terms either do or do not hold. You are begging the question by presuming that they do without showing why.
 
@Expert Are you calling me a LOVE BIRD????
 
If you know that they do hold, then you a.) either have no actual question, or b.) have a motivation and are withholding it for no reason.
 
7:54 PM
@Arkamis Oeis is for integer sequences , not for real ones and the probability of success apart from number theory , basic calculus , topology or combinatorics is very small.
 
@mick OEIS was a singular example. I can cite dozens of other such examples.
 
@Arkamis Showing WHY is proving it and IS the answer I seek , hence the question !
 
where can I see angle $\beta - \gamma$ in triangle $ABC$ (standard notation all)? I need this for algebra, huh...
 
@Mick Why is 2=3?
 
@mick when you don't motivate us, we won't solve it for you
 
7:55 PM
You cannot just say "proving why is the proof" if your premise is false.
 
Just received a flag for this room. What is going on?
 
I ASK WHY and you guys must answer it. and 2 is not 3. Do not insult me with 2 = 3 nonsense.
 
@allquixotic Looks like someone flagged the april fools bot.
2
 
@Arkamis
 
And if you have not established validity of your premise, and you have not deemed it worthy of your time to support that claim, then it is not a question worthy of the community.
 
7:56 PM
@Wipqozn Oh, okay :D
 
@Arkamis it seems correct. if it is easy to be shown false , run a program and show a counterexample !!
 
@Expert remember that foo
 
That burden is not on me.
I don't care about your question
 
@Raindrop Yes.
@Arkamis Well done, sire.
 
And apparently neither does anyone else, because you have not given us incentive to care.
 
7:57 PM
interesting, I was not flagged the first time I called skullpatrol and chuckie lovebirds (to their faces!)
2
 
@Arkamis because you do not want to answer the question. Being unable to answer my question does not make my question bad. Being not intrested is not my fault either.
 
Being not interested is not your fault but it is your penalty to pay if you want the question answered.
And if you are willing to pay that penalty, then don't come in here and complain about it.
And try to philosophize around it.
 
@Expert you really should run ELIZA (IIRC there are JS libraries for it, and you can easily join it with Zirak's SO chatbot library) in chat
 
alright, cool... I'll be sure to ignore any flags on @Expert ;-) they're an expert, after all. they must know what they're doing.
 
@allquixotic Exactly! People can't just name themselves expert if they weren't an expert.
 
7:59 PM
@mick You're spreading silly stuff again? Did my advice serve no purpose?
 
Is it true that if $A$ rank $n$, then every single column of $A$ is linearly independent?
 
@Wipqozn No kidding! You are totally right. I got my question answered by an extremely helpful expert on Super User earlier today. I didn't even have to ask a question! They knew I needed help on installing the Gnome Ubuntu theme on Gentoo right away.
 
Only if $A$ is $n\times n$
Or $n\times m$ with $m < n$.
 
@allquixotic I swore at my expert to see what would happen. He left :(
 
I'm a little disappointed that the experts don't have any memory ability like the Alicebots. "Remember that <foo>" always elicits "OK, I'll try to remember that." and it has a chance of showing up in their gossip file
 
8:01 PM
If $m > n$ it is easy to see that not every column is linearly independent. Example: $\begin{pmatrix} 1 & 0 & 2 \\ 0 & 1 & 0 \end{pmatrix}$
 
"Tell me some gossip" is fantastically hilarious when asking it of a public alicebot with a long-running gossip file.
they probably disabled that feature for performance reasons ;-D
 
@PeterTamaroff what silly stuff , what advice ? the advice yesterday was to put the question on main , what i did !
there are no math errors
!
 
@mick No, I told you something that got starred quite some time ago.
 
@PeterTamaroff what ?
 
@mick I told you to study properly.
 
8:07 PM
@allquixotic i remember alicebot
@PeterTamaroff what do you mean by that ?
I could not find such things in the books!
 
If $A$ is an $n \times n$ matrix, does $A \text{ rank }n \iff A$ has linearly independent rows AND columns?
 
hi
 
@raindrop the rows are linear independent and the columns ar elinear independent
 
I DO NOT WRITE A BUNCH OF SHIT THROWN TOGETHER !!! :/
 
8:08 PM
@κρανίοπεριπολία how are u skull?
 
@pourjour Fine thanks, how are you?
 
@κρανίοπεριπολία I'm good thanks
 
@Expert I don't considerate it as an offense
 
@Charlie hi
 
@Charlie people are not nice to me :/
 
8:10 PM
@mick Well, to get a good calculus book and start from there.
 
You have to be nice first. :-)
 
@PeterTamaroff I have a calculus book and it does not help !! Its not an integral or a limit !!
 
$p^2|a^2 \Longleftrightarrow p|a^2$
 
@mick Help with what?
@pourjour Yes.
 
could someone please check this if it's correct
 
8:11 PM
$pq\mid a$ then $p\mid a$ or $q\mid a$.
 
@PeterTamaroff with answering my question of course
 
In particular $pp\mid a^2$ then $p\mid a^2 $ or $p\mid a^2$.
 
I do not write a bunch of shit :(
 
@mick Link?
 
@PeterTamaroff thanks
 
8:12 PM
0
Q: Question about $f(n)=f(n-1)+ln(f(n-1))$ with $f(0)=2$

mickLet $n,m$ be positive integers. Let $f(0) = 2$. Let $f(n)=f(n-1)+ln(f(n-1))$. Let $h(n,0)=arcsinh(\dfrac{n}{2})$ and $h(n,m)=arcsinh(\dfrac{h(n,m-1)}{2})$. Let $g(n)=\Sigma_{m=0}^{\infty} h(n,m)$. Conjecture : $2+ln(2)n(g(n)-4)<f(n)<2+ln(2)n(g(n)+4)$ Is this true ? How to prove it ? What...

 
@pourjour Sorry.
@mick Please make it [text](link)
 
@PeterTamaroff why?
is it necessary
 
sometimes a gem looks like shit :)
 
@PeterTamaroff Are you asking for mat?
 
@pour hi @mick what can I do?
 
8:15 PM
@mick Why are you conjecturing all that?
 
@pour hi @mick what can I do?
When I thought anon couldn't choose a worse gravatar
 
@PeterTamaroff because it seems true and intresting but I do not know how to prove it. Which is often the reason logically.
 
@mick It seems pretty made up. I mean, forced.
Not that you're lying.
I mean...
 
@mick you didn't even showed a single case where it is true
 
@Charlie how are u?
 
8:17 PM
@Charlie Do about what ? about ppl being not nice ? I dunno. I just felt the need to tell you. I prefer people answering my question and I go like : I was an idiot , then the opposite : ppl not being nice to me without giving an answer
 
What did you do, test it in some programme? @mick
It seems very forced.
 
@PeterTamaroff Yes in excel and maple.
 
@mick Up to...?
 
@pourjour fine, you?
 
but is there an implication or equivalence for example can we say:

$p|a^2| \Rightarrow p^2|a^2$
@Charlie I feel good thanks
 
8:19 PM
@pourjour If $p$ is prime, yes.
 
@PeterTamaroff but we must chechk if $(p,p)=1$ before telling that $p^2|a^2$ which is impossible
 
@PeterTamaroff up to 4 relevant iterations of arcsin but im not sure about the roundoff errors/numerical precision. I know it seems forced , but thats why it amazed me.
 
@pourjour No, no.
 
@DominicMichaelis you can check yourself
 
My meta profile says I have visited for 314 days, and my mainsite profile says I have visited for 628.
 
8:21 PM
@pourjour splendid
 
@Expert I tought you were a bot
@PeterTamaroff so the relation is correct with equivalence
 
@pourjour thought.
 
not well understood =/= random shit.
 
Taught comes from "teaching".
 
guys didn'T you notice that expert is writtin in italics
who is the only one which names is in italics ?
 
8:24 PM
@PeterTamaroff thanks
 
@pourjour OK. Suppose $p$ is a factor in $a^2$, but $p^2$ isn't a factor in $a^2$-
 
p|aa=>p|a=>p^2|a^2, yeash
 
I DONT BELIEVE YOU DIDN'T NOTICE.THAT!!!!!! I
 
wut
 
@Charlie who ?
 
8:25 PM
@PeterTamaroff not always
 
@mick Uh?
 
@DominicMichaelis that expert is anon...
 
@PeterTamaroff what will happen then?
 
@mick How did you come up with the $+2$, $\log 2$, $\pm 4$, etc?
Tell the people how you came up with that.
 
@charlie was kind of to obvious i think
 
8:26 PM
It looks uninteresting laid out like that.
 
@PeterTamaroff But that is trivial , it comes from the first 3 iterations.
 
@pourjour The thing is that $p$ is prime. If $p\mid a^2$ then $p\mid a$ or $p\mid a$. Since $p\mid a$, then $p^2\mid a^2$.
 
we start with 2 , 2 + ln(2)
@PeterTamaroff
 
@DominicMichaelis very obv
 
8:27 PM
@mick "Is trivial" deep sigh
 
@PeterTamaroff why the sigh , it is trivial not ?
 
:8771098 If $p\mid a$ then $pk=a$. This means that $p^2k^2=a^2$, yes?
 
d|n means n=dk for some k, squaring yields n^2=d^2*k^2, hence d^2 divides n^2
 
or should i say intuitive
 
@Expert wow...
 
8:28 PM
more generally, a|b and c|d imply ac|bd
 
@mick Why do you think that because the iteration starts with those numbers, they should appear in the bounds?
 
@PeterTamaroff if we supposed that $n^2+1 \equiv 0 \mod{p}$ and $(p,n)=1$ how can I prove that $(n^2)^{1+2k} \equiv 1 \mod{p}$
 
@PeterTamaroff that is just a guess. But 2 + ln(2) + ln(2+ln(2)) is close to 2 + 2ln(2).
maybe i should add the tag " experimental math " or such , if that even exists.
 
@pourjour not true unless p=2
 
@PeterTamaroff if we supposed that $n^2+1 \equiv 0 \mod{p}$ and $(p,n)=1$ how can I prove that $(n^2)^{1+2k} \equiv 1 \mod{p}$
 
8:35 PM
@pourjour Didn't you read what anon just gave you?
 
do you mean what I'm trying to prove is false
?
 
if n^2 is -1 mod p then n^2 raised to an odd power is also -1 mod p, and -1=1 mod p iff p=2
 
that's what the goal of exercise is to find a contradiction
 
O... kay...
 
@Expert I already find $(n^2)^{1+2k} \equiv -1 \mod{p}$
 
8:38 PM
@anon: hey,
how are you?
 
@CтарыйДжон How are you today?
 
alright
 
Hey who is voting to close my question !!! ????
 
@pourjour Hi - I am fine, thanks. How are things with you?
 
@mick shall we?
 
8:39 PM
@Ilya Why ?
 
@mick well, if somebody does, there's perhaps a reason?
 
with what lame excuse ?
that nobody can answer ?
 
read the stared message
 
@CтарыйДжон everything is fine , thanks :)
 
its NOT a bunch of shit !!!
 
8:40 PM
@mick if you talk about this one, it would be good to add some motivation and your own ideas
 
@PeterTamaroff any idea
 
@mick: ah, Arkamis already told that in a bit more direct fashion
 
@Ilya you believe that. there is no proof that it would be good. motivation is subjective.
 
@pourjour Dear Baby Jesus. Are you oblivious to what anon is writing?
 
@mick I just answered your question
 
8:42 PM
@Cтарый Джон Hi
 
@mick People are voting to close because anyone reading that without some further explanation will go: Dafuq?! Why would I wanna solve this crazy recursion?
 
@Ilya lol no answers yet when i looked.
 
@mick I mean, I replied to your question "why are they closing mine post"
you may take this opinion into account, but you decide
 
hhhhhh, yes I read it and I gave him an answer I told that I already find that: $(n^2)^{1+2k} \equiv -1 \mod{p}$
that's was the question of the exercise then the next question is to prove $(n,p)=1$ then the next question is $(n^2)^{1+2k} \equiv 1 \mod{p}$ not -1 this time to find a contracdition in the end.
 
8:44 PM
It silly to close if you do not know if the statement is false or true. You should upvote a good question or even better give an answer , if you cant , dont judge.
closing question that are not nonsense is gay !
@CтарыйДжон Im having some trouble here , they want to close my question. The one you advised me to put on main.
 
@mick "We expect answers to be supported by facts, references"
 
@PeterTamaroff So do I.
 
@mick so you would upvote when i ask "Prove RH"
 
@DominicMichaelis If you were the FIRST one , yes !
isnt it worth considering that iterations of arcsin(x/2) and x + ln(x) might be related ??
 
@PeterTamaroff I forget to tell that $p=3+4k$
 
8:50 PM
@mick I don't think I advised you to post in on main in that format - I think I included some such words as "if you can formulate a decent question ..."
 
@CтарыйДжон why is it not decent ?
 
@mick do you see the starred message ?
 
the math is correct !?
 
i guess i am repeating
 
@mick I have not said it is not decent
 
8:52 PM
@CтарыйДжон the math is correct and formal ?? so ?
@CтарыйДжон " if you can formulate a decent question "
 
@CтарыйДжон so whats the difference ?
isnt an inequality decent ? do i need more text ? math is about symbols not ?
 
@mick for how many cases did you try out ?
it's not math its some random inequalites
 
@DominicMichaelis alot. and its not random !!!! random is an insult to math.
 
@mick you are making deductions about my statements which do not logically follow - but to be honest, I find the question unmotivated and not well presented. I have not voted to close, but I can see why others might.
4
 
8:55 PM
@mick it was intented as an insult, you are to lazy to think about (or at least to lazy to show us what you were thinking) and we shall solve it for you
 
@CтарыйДжон if they would follow logically , I would have already had a proof. the question IS show that this follows by logic !
@DominicMichaelis Im not lazy , im just not able to solve it myself , hence i posted it here after trying days !!
afterall this is a Q and A !
 
so and we shall waste some days with the same things you tried and failed ?
 
@DominicMichaelis If you are a better mathematician then me you can answer it faster !!
and if you are not , you do not have the right to vote close simply because you are confused just like me !
 
ok suppose i am a better mathematican than you. Why should i waste my time with a noob question which doesn't give me any reason to solve it ?
 
@PeterTamaroff I find I used Fermat theorem $n^p \equiv n \mod p$
 
8:59 PM
@DominicMichaelis since the answer does not follow trivial , its a good excercise and you will sharpen your skills + get many rep from it.
 
@mick You should upvote a good question
 
@DominicMichaelis also , im not that noob.
@Ilya I did.
 
how do you know the answer is not trivial ? how do you know it is a good exercise? why should i care for reputation
 

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