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08:04
someone said that i am wrong, cause wolfram says the function doesn'T have a pole
@jasper hi
user19161
@DominicMichaelis Huhu!
i still find this funny
08:40
How you prove that the sum of 1, when sin(n) > 0 and -1 else is bounded here
08:59
periodicity of sin?
BTW, I cannot understand why here wolfram fiinds no poles at all.
while here it claims to have a pole...
i don't unterstand that too
i guess it is to easy for wolfram
@JayeshBadwaik I am studying variational analysis from Enrico Giusti book, if this was what you asked?
@JayeshBadwaik I mean this one.
@awllower as i usually only use mathematica I never ask wolfram for poles, just mathematica for hte residues
09:03
Oh
I know nothing about mathematical softwares except matlab...
@JayeshBadwaik And PDEs I learn a little from Evans.
bro matlab is no mathematical software
matlab is crap
@awllower yes, Van Lint is another book. Someone from chat was using it, I forgot who and thought it might be you, hence my question.
Really!
@JayeshBadwaik I see.
in matlab taking derivates of polynomes is not linear
@DominicMichaelis @DominicMichaelis Might I ask why you said so?
You mean: it uses approximations?
09:06
i think all the syntax is just an error and those autoscaling of matrices and that you can't enter a single scalar
try: 1-uint8(2)
Sadly I must have taken that course in my university...
@DominicMichaelis I do not understand: is it some kind of algebraic groups??
:)
uint8 is an 8 bit integer without a sign
I see.
09:08
and matlab autoconverts to the lowest format
so 1 -2 = 0 here
Indeed: I encountered that problem before as well.
or [1 -2] = (1,-2) but [1 - 2]= [-1]
I once laughed out loud at that . :D
good luck finding an error if a library makes it ;)
09:12
or try [pi e int8(3)]
Alright: depart time again!
Bye!
@DominicMichaelis I shall try later. :D
@DominicMichaelis matlab is good for engineering. it has a niche there, similarly as the R language is good for statisticians
maybe but i am not an engineer
real men need real numbers, not machine numbers g
09:15
@DominicMichaelis bleh..... :P don't get into real men and stuff. ;-)
just a joke ^^
Yeah....
i prefer my numbers to be variable ^^
Hmmm, there is sym keyword in matlab which goes to help somewhat, but matlab is not for mathematicians, that is true...
by the way what does NM means here
09:23
no idea
@DominicMichaelis never mind
He apparently had made comment suggesting something earlier but it didn't apply
so he deleted the comment and said never mind
 
1 hour later…
10:40
Don't you worry, don't you worry now!
10:59
Dantzig’s Two-Phase Method for MINLP
1. Convince the user that he or she does not wish to solve a
mixed integer nonlinear programming problem at all!
good to see mathematicians have some humor
11:10
@CBenni after reading Mixed integer nonlinear programming problem
i absolutly sense no feel of solving something like that
I dont either, tbh.
But I am searching for an easy solution...
too bad I wont be able to find one.
procrastination ?
@DominicMichaelis How is that procrastination? Its just that MINLP is NP-hard. So basically, there is no easy solution to it
I might just use the NLP+roundoff approach
procrastination is doing it tomorrow
when trying in mathematica, that gave decent results
11:14
i think that should work :D
however I have had results of like 1.4 for variables
rounding there is... welll. nonoptimal
might then try both values and pick the one that is better
11:48
This edit has been wrongly reviewed by me. Maybe someone else could repair my error? Thanks...
Hey guys, I hope i'm not breaking any rules here, but:
An abelian group of order 4 is either isomorphic to...
what is the logic behind coming up with an answer
can anyone run me through it?
Do you know the Lagrange theorem?
sure do !
Then every non-identity element of the group is either $2$ or $4$.
sorry what is $2$ ?
12:00
2
Just ignore $.
Oh, I see the habit you're in :P.
but yes.
And every subgroup of an abelian group is normal, right?
is that a theorem?
have not seen that
Commute -> Normal.
OBVIOUSLY.
Do you know what is a normal subgroup?
apologies.
12:01
OKOK
hello
Then, if there is an element of the group of order =4, then surely that element is a generator of the group, and the group is cyclic, right?
@caveman Hi!
right.
So suppose that every non-identity element is of order 2.
Yep, I'm with you.
12:04
And show that, for two distinct elements x, y, the group is isomorphic with the direct product of <x> and <y>.
<x> is the subgroup generated by x.
hmm alright.
Maybe this is too formal, lack of intuitions?
I shall give that a go. Thank you for your help. Muchly appreciated
np :D
@caveman How do you do today?
feel bad
12:07
What for?
maybe since I just woke up
I see.
:D
are you recovering well
Oh yeah!
One can barely find any remaining charcater of the wounds!
that's wonderful
12:09
ja :D
I can even play basketball again!
although I am a bad player, haha
Wow, you are a fast healer.
It seems so. :)
maybe I am some monster---group? haha
Sorry to seem very rude (I have an exam tomorrow), but what is Z/3Z , where Z is the set of integers.
Is it related to cosets?
Z not 3Z
Of course it is related to cosets!
3Z is a subgroup of Z
And Z/3Z is the set of cosets of 3Z in Z.
Excellenteeee' !
12:20
:-)
Thanks then.
no, thank you ^_^
12:33
I got a lot of attention form y diophantine question
but no theoretical insight
What do you mean by theoretical insight?
it's just strong computer power applied to the question
I see.
But the answer by Yimin provides some insights at least?
You guys are amazing. Eat and breath mathematics.
Albeit in the nature of comments...
We are no more than cavemen! :D
12:39
:p
ok his answer is very interesting
But apart from that there is nearly nothing, all numerical... At least in my view, as I know nothing about numeric anamysis...
@caveman As soon as I saw it it reminded me of part of the content of one of the answers (the part about it being congruent to something divides by $e$ rounded down mod $p$)
since showing that was a problem of the day on the EFNet IRC channel some years ago
the e trick is very interesting
an unusually slow day on Arxiv
12:45
@caveman Hey look you are here!
only 2 in group theory and 5 in representation theory
nice
haha
@awllower Think I got a badge for going to that link. Thanks. :)
haha
:D
NP
12:51
yeah, there is a badge for reading the entire thing (or at least scrolling to the bottom of the page)
I think that the photo of caveman is the symbol of this site. :P
A bunch of cavemen is crowding around a fire.
user19161
@eXtremiity Breathe is the verb and breath is the noun.
Hm...
I think I am tired enough, so i shall take a rest.
Later then!
13:02
good night
13:15
Haha! Thanks @jasper
man !! i hope I do well in my abstract algebra test tomorrow
pretty excited.
13:48
Oh cool. My name is Gustavo too.
> if all time ever wasted on Failbook would have been invested in fusion research, the first commercial reactors would be under construction by now.
@caveman Yes.
It's ' nice quote. Sad but true.
@GustavoBandeira the book is basically one giant table of properties of specific matrix lie groups with derivations
that sounds really dull
13:59
@anon Is this good or bad?
your mileage may vary
i cant brain today what should i do isntead
user19161
@GustavoBandeira This is too advanced for you, wait a few more years.
user19161
In fact, there is no need for any Lie thing in undergrad...
user19161
Today I got 100 points for doing a factorisation.
user19161
14:14
Also, today I did my 400th post.
15:07
frankly I find your answer close to useless (it's ad hoc and not amenable to obvious generalization, whereas a sleek cyclical solution is a standard textbook answer here), and the displayed method of handling obsolete comments ("remove it," "leave me alone") inappropriate and whiny.
2
15:27
Hellooooooo
@κρανίοπεριπολία hi skull!!!
No one else will say hello?
@Charlie I just got here!
Hi Ed
so, Hello!
15:34
hilo...
@JayeshBadwaik halo
@Charlie hilo....
@JayeshBadwaik wtf?
someone can help me with technical issue?
15:48
away....
I alresy asked it as a questions, but I will write it also here:
@JorgeFernández ¡Hola!
I try to post question but I always get the message: This post does not meet our quality standards.

For example: I try to understand why by definition

[c0,c1,...cn]=[c0,[c1,...cn]] and also
[c0,c1,...cn]=[c0,c1,...c(n−2),[c(n−1),cn]] .

But not [c0,c1,...cn]=[c0,c1,[c2,...cn]] for example.

or this:

P is a prime such that q=p+2 is also a prime.
I need to prove that there is an integer a such that p|a2−q if and only if there is b such that q|b2−p.
@user1932595 do not write twice, just link....
15:50
good idea :)
0
Q: This post does not meet our quality standards.

user1932595I try to post question but I always get the message: This post does not meet our quality standards. For example: I try to understand why by definition $[c0,c1,...cn]=[c0,[c1,...cn]]$ and also $[c0,c1,...cn]=[c0,c1,...c(n-2),[c(n-1),cn]]$ . But not $[c0,c1,...cn]=[c0,c1,[c2,...cn]]$ for e...

@user1932595 try to add the tags, good title and then just fill it up with random words which you can delete after the question is posted
it needs you to have a certain number of words and stuff
In the first question, you have not described what do the brackets mean. Explain the question in more detail. Also show your work and similar things,
@user1932595 well, the first example really is a bad question
and the second one may simply have been because of the short length, but that does suggest you should add some thoughts
Hm.. I wonder if one can approach this question by constructing a cycle decomposition like one would for a bijection.
@JorgeFernández that's some really bad advice. The quality control software is not yet so bad that we should advice people to ignore its restrictions. So, rather, we should try to improve the question rather than to bypass the system.
15:56
@user67848 I doubt that would work, as the assumption from the start is injective and bijective is what you want to show
@TobiasKildetoft But it really is a bijection, so we pick an element in the codomain and show that it comes up again after repeated application of $f$ (of course, through other means than just assuming it is a bijection).
@user67848 but what would that tell us?
@TobiasKildetoft That it is surjective!
ahh, right
I think it really just obfuscates the normal induction argument though.
15:59
probably
16:14
@JayeshBadwaik Sometimes the question can be posed concisely and adding more things just makes it worse.
I think Caveman left in anger ...
16:59
@HenningMakholm yes, that's unfortunate
@DominicMichaelis hi
Guys, how can I learn math without becoming mentally instable?
Also: does anyone know when debian 7 will be out?
Easy -- you learn math. Mental health is unrelated to your ability to do math.
@arkamis Not if you are born being good at it, but studying a lot of time does.
I still fail to see how an innate proclivity to learn has anything to do with mental health. As far as is known, the two are uncorrelated.
If you are going to become mentally unstable, it is going to happen regardless of whether you learn math, ballet, the piano, or chinese.
@JorgeFernández You'll need to be a lot more specific about what problems you have if you want to have any chance of a relevant answer here.
17:07
Have you ever found that your mind becomes stuffed and you can't concentrate after some time of studying?
Yes, that's called "fatigue", and the same effect happens after a long period of video gaming, reading, cleaning, repairing your house, or playing a sport.
It also happens because active thought actually does use energy, and people tend to neglect nutrition and/or adversely modify their diet during prolonged study sessions.
Because of the structure of our working schedule, prolonged study sessions tend to go late into the night, which means that the fatigue is also an effect of natural circadian rhythms.
what is a circadian rythm
Your wake/sleep cycle
"circadian" coming from "circa" or "around" and "dia" from day. So literally, the rhythm of the cycle of a day
If you want to be effective at studying, do it in between normal meals, during normal waking/working hours, and take breaks frequently.
Drink plenty of water, and avoid high-sugar foods.
17:12
why avoid high sugar?
They're basically terrible for you, and affect your ability to concentrate
fruits are good, candy is bad. I actually like to have beef jerky when I study. High protein, a little salt, something that you can munch on slowly.
@Arkamis how is the fruit sugar better for concentration than regular sugar?
@Arkamis but regular sugar is a disaccharid, not a polysaccharid
just like fruit sugar
ohh, woops, I recalled wrong
which theorem does she mean here ?
17:17
fruit sugar is mono
@TobiasKildetoft The sugar is probably more or less the same (though fruit generally contains fructose whereas refined sugar is almost 100% sucrose), but fruit also has a fibre content which you won't find in candy.
@TobiasKildetoft I mean more generally like HFCS-based foods.
right, but the entire argument about sugar being bad for concentration was what I was objecting to
I should have been more specific when I said "high-sugar"
what about music?
17:20
There are various studies. I personally prefer music that I enjoy but that is quieter and slower-tempo
I don't want to get so caught up in the music that I start listening to the song.
@JorgeFernández What about that? Some people concentrate better with some background music; others like silence. Do whatever works for you.
what about narcotics?
Generally narcotics are a bad choice, not only for learning math, but also life in general.
@JorgeFernández Definitely yes, if you're Erdös. Otherwise stay away.
17:22
caffeine
Caffeine? I think you mean cocaine
@JorgeFernández Okay, the answer to your next 10 questions is going to be "find out whether it works best for you with or without, and then do that".
2
But don't do drugs. Drugs are bad, mmkay?
Yes
Don't do drugs,.that's today's lesson
17:24
Hi folks
When I mentored students, they would often ask how to cram for an exam. I used to tell them to sleep. You have weeks to learn the material; the chances of you truly absorbing and retaining advanced math while sleep-deprived, some three hours before a test, are minimal, and often to the detriment of the things you already know.
I used to read for pleasure the day of my exams. Nothing I was gonna learn then that I didn't learn in the preceding weeks.
@CameronBuie you just made the same proof as I did, with your edit
@CтарыйДжон Evening!
Does anyone here know about Prüfer code?
17:32
Can't say I do
has anyone read a course in combinatorics van lint and wilson=
?
17:55
nope sry
it is much easier to get reputation when you already have a lot of reputation lol....
credibility
if 2 users give the same question usually the one with higher repuation get's a lot of more upvotes
18:40
capped :)
@robjohn: Excuse me. Is there an option for Moderator to implicitly assign wiki to one's answer such that he/she will not get reputation? "Implicitly" mean the wiki label does not appear visually. I wonder some of my answers get upvoted but my reputation does not increase while my rep has not exceed the daily limit of 200 upvotes.
I am talking for tex.sx site.
It should be the same moderation panel i think.
18:49
Just for a reference, please kindly look at this: tex.stackexchange.com/users/19356/karls-students?tab=reputation and see "How to plot functions like ‎‎‎‎‎x=f(y)‎‎ using TikZ?" does not contribute any reputation to me while it is not wiki answer. :-)
ask in meta ?
Look up "Community Wiki" or CW.
@DominicMichaelis NO. I am talking about the main site rather than the meta site.
My answers in question are not in wiki type.
@Karl'sstudents he is saying, ask the question about "not getting rep" in meta.
@JayeshBadwaik Maybe. :D
18:59
@Karl'sstudents The 200-points-a-day limit applies before what you spend on bounties is deducted.
@HenningMakholm Wait... I am checking the time stamp first.
@Karl'sstudents OT: Why should I use pdflatex \input{filename} instead of pdflatex filename?
@JayeshBadwaik OT?
@HenningMakholm You might be correct! THanks!
@Karl'sstudents nope, the only way you wouldn't get votes should be if you've capped or the answer is marked CW
@Karl'sstudents Off Topic.
19:05
@JayeshBadwaik It has been asked by someone in the main site. I will give you the link shortly.
18
A: Rationale to use \input{filename} on the pdflatex command line?

Heiko OberdiekAdvantages It is a good trick, if someone wants to put TeX code before. Examples: pdflatex '\def\foo{bar}\input{filename}' pdflatex '\includeonly{introduction}\input{filename}' or inside \write18 (shell escape feature): \immediate\write18{\detokenize{pdflatex '\def\foo{bar}\input{filename}'...

@Karl'sstudents The comment above yours, "Chatting requires 20 pts", confused me, because I'm seeing chat with a way smaller font than that :-)
5
@HenningMakholm Hahaha
Has anyone noticed the vote counts next to the "related questions" column in a question page before?
@HenningMakholm When did this feature start appearing?
user19161
@κρανίοπεριπολία Hey hey.
user19161
Is caveman gone?
user19161
19:20
OMG, caveman is gone!
user19161
I really got pissed with caveman too for calling people rude again and again and again.
user19161
Nobody is being rude to caveman, but he keeps calling people rude, which is a kind of insult to me.
user19161
@κρανίοπεριπολία I might be gone soon too...
19:24
...we all have to go sometime.
Life is a journey with death as the destination.
NONONONONONONO i can't watch it on youtube
@jasper huhu
user19161
@κρανίοπεριπολία And in my belief, there is rebirth.
user19161
@DominicMichaelis Huhu.
i reached the 8 k
12 k to go
Someone stole my egg in the refrigerator. :D
19:28
@Karl'sstudents A few hours ago, I think.
@HenningMakholm Thanks. So a few users realize it.
user19161
Hey @henning nice to see your beard!
user19161
Hey @alex finished thinking about your proof to my question?
what question?
user19161
19:31
@JorgeFernández He knows. Look for my most lowly voted question...
@JasperLoy Oh that one? I don't think there's a way to rescue it that hasn't been covered by the other answers.
@JasperLoy I should probably just delete it.
user19161
@AlexBecker Yes, I think so too! Anyway, I look up to you as an extremely smart undergrad!
user19161
Hey @jayesh actually I still think your answer to my question is wrong. If you feel so too you can delete it...
@JasperLoy It's done. Thanks for your kind words blushes.
user19161
Hey @jorge you asked when Debian 7 will be out? I am waiting too, maybe this weekend, maybe another month.
19:34
thats cool, so it isn't long then?
user19161
Hey @jayesh sorry but I have removed the upvote on your post.
@JasperLoy Back to blue, I see.
user19161
@HenningMakholm Yes, and trying not to change my username so often, lol.
@JasperLoy I never know if it's you when I see someone with a plain monochromatic square beside them.
user19161
@AlexBecker Just don't forget me when you win the Fields medal!
user19161
19:38
@HenningMakholm Haha, just look out for the few stupid questions I have asked!
@JasperLoy Out of curiosity, are you a university student?
user19161
@AlexBecker No, I finished my undergrad long ago. I will be turning 32 later this year. I hope to apply to grad school some time in the future. Maybe I will try to enter when I turn 35 and finish my PhD at 40...
@JasperLoy because they're round numbers?
ha ha ha @(removed)
user19161
@AlexBecker Well, because some life events cause me to make plans this way, and that is one possibility which I have been thinking about for a while...
19:41
@Karl'sstudents There were a few minutes of downtime right around the time I posted this comment. I assume that was it.
@HenningMakholm Nice "debugging" skill.
user19161
7
Q: Existence of $\vee$ or $\wedge$ for non-monotonic functions

Jasper LoyThis question is inspired by a discussion in chat with wj32. We allow for equality in the definition of increasing and decreasing and call a function monotonic if it is increasing or decreasing. If $f:R\to R$ is not monotonic, are there three points $x<y<z$ such that $f(y)<f(x),f(z)$ or...

user19161
By the way guys, I really feel like advertising this question of mine again, which is what is being talked about above...
user19161
It is something which seems straightforward at first, but the only proofs so far seemed rather nontrivial...
@robjohn i closevote cause of his comment
and there have been an answer to that time
user19161
19:55
@AlexBecker I actually hope to apply to Chicago, but I think they will never accept me...
@DominicMichaelis yes, but now others who might want to answer cannot. This sounds more like a personal disagreement. At least 4 others agree with you, so I am only commenting.
thats always the way when a question is voted and i read it several times
user19161
In other news, I have decided to use mathbb for my reals etc from now...
good dicision i do it too
user19161
Also, I think I will take a break from answering and try to edit my existing posts into better shape instead.
19:58
@JasperLoy I have never used anything else. I don't even know the alternatives :-)
user19161
After I have edited them to my satisfaction, I may consider deleting my account.
@JasperLoy again?
Are we talking about this?
user19161
So Chicago you heard it, I am coming for you...

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