# Математика

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International Math Thread Аноним 10/11/17 Птн 16:13:10
Welcome to /math, stranger!

This thread is the place to discuss anything math-related. No captcha, no moderation[1], no cancer. Please be respectful and provide proofs if requested, do not shitpost and don't be an attentionwhore.

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[1] One exception: NO CYRILLIC SHIT ALLOWED IN THIS ITT THREAD!
[2] https://pastebin.com/raw/d455mKrS
Аноним 10/11/17 Птн 16:14:13
Аноним 10/11/17 Птн 17:20:47
>>27513 (OP)
Mathematics is, in it's essence, study of modules over some rings.
Аноним 10/11/17 Птн 17:27:14
>>27524
> in it's essence
> it's
Reported. No cyrillic shit allowed in this thread.
Аноним 10/11/17 Птн 17:32:11
>>27525
I see you've been having comprehension problems.
Аноним 10/11/17 Птн 17:49:48
>>27514
>WE
>won't allow
>emergence of mutual hostility between nations
Is this picture supposed to match your attitude towards people here, or the exact opposite?
"Cyrillic shit" – what?
Аноним 10/11/17 Птн 18:18:45
>>27529
>>emergence of mutual hostility between nations
Go away. You are not allowed in this thread. Reported.
Аноним 10/11/17 Птн 18:20:14
Аноним 10/11/17 Птн 18:27:22
From now on, this is "silly hatred over misspelling" thread.
Next time, please don't try to pretend you want to discuss mathematics.
Аноним 10/11/17 Птн 18:58:37 2753810
>>27513 (OP)
They had started to have a general mathematics thread there on 4chan recently. Better force it there.
Аноним 10/11/17 Птн 19:03:21 2753911
Be aware, stranger. You've now entered teenage-elitism conrer.
Complacency and self-smugulatory thrive here.
Аноним 10/11/17 Птн 19:04:57 2754012
>>27538
>force it there
Master Yoda, is it you?
Аноним 10/11/17 Птн 19:15:06 2754113
Аноним 10/11/17 Птн 19:19:04 2754314
Аноним 10/11/17 Птн 19:20:09 2754415
Аноним 10/11/17 Птн 20:04:50 2754716
Hi im from Anglia im now be living with you.
Аноним 10/11/17 Птн 20:21:00 2754917
Аноним 11/11/17 Суб 00:13:11 2756618
>>27513 (OP)
Well, lets make constructive dialog.
How evaluate e?
Аноним 11/11/17 Суб 07:22:27 2757019
I was waiting two years for this thread
Аноним 11/11/17 Суб 09:40:05 2757720
>>27566
by taking cohomology of loop space
Аноним 11/11/17 Суб 10:27:37 2758021
All right fags, tell me how to fucking factorize vector spaces. And don't give me the Wikipedia definition, it doesn't help. If I need to find V/W, would it be enough to take a basis in W, complement it up to an orthogonal basis in V, take just the complement and span the shit out of it? If so, what do I do if I don't have a scalar product and can't make an orthogonal complement?
Аноним 11/11/17 Суб 10:36:20 2758222
>>27580
>what do I do if I don't have a scalar product and can't make an orthogonal complement?
You can though. It suffices to show that the p-th cohomology of the (p-1)-th homology of W vanishes for every prime number p. Assuming the axiom of choice, this actually holds for any vector space.
Аноним 11/11/17 Суб 14:39:06 2759923
>>27582
fed a fat one
Аноним 11/11/17 Суб 17:52:42 2761824
>>27577
>>27582
Sorry, but cohomology is not a part of math. Why you type such thing at this board?
Аноним 11/11/17 Суб 18:18:13 2762025
>>27618
Mathematics is just a branch of algebraic k-theory. K-theory in itself is "the most natural cohomology theory". Mathematics is part of algebra. Whereas in math, we mostly study modules over rings (which form abelian category), in algebra we also sometimes study derived categories (which is not necessary abelian).
Аноним 11/11/17 Суб 18:20:12 2762126
Аноним 11/11/17 Суб 19:22:15 2762827
> картофаном
What it means?
Аноним 11/11/17 Суб 19:53:23 2763228
>>27628
Cartofan means potato.
Google Timothy Gower's paper, "Two cultures in mathematics". He points out, that there is "first culture" of abstact theory builders, such as Andre Weil, Grothendieck and his colleagues/students, other people like Michael Atiyah, John Milnor, etc; and "second culture" of concrete problem solvers, notably hungarian combinatorics, such as Paul Erdos.
In Russia, we associate with second culture an old and bold guy, some university professor (usually in some small province near siberia, but he may be from MSU too) who interested in such fields as classical analysis with asymptotics, numerical methods, and applied math in general. Those people are notorious for hatred towards abstract algebra and obsession with general topology and descriptive set theory. We think of them as really just local scientific communities, with mutual references in small journals issued by university where they teach, mutual love for vodka, maybe with some pickled cucumbers, black rye bread, roasted pork with potatoes. You know, simple people, simple cuisine.
Hence the name.
Аноним 11/11/17 Суб 20:15:40 2763829
>>27628
One important thing to add is that "second culture" which come mostly from simple people of province as it was mentioned usually represented by ethnic russians. And "first culture" of moscow school in russia is traditionally jewish which is also explains part of a sceptic attitude towards kartofans.
Аноним 11/11/17 Суб 20:30:30 2763930
>>27638
What you implying here, kinda lost its significance with the fall of the soviet union. It is true that jewish students applications were commonly rejected due to discrimination policy back in those days, but now it's no longer the case.
And i myself, being ethic russian from small province and yet still fascinated and riveted by Grothendieck-style mathematics, find your claim somewhat offending.
Not being judophobic in any meaning, I'm not familiar with any person of askenazi heritage. Though i don't like vodka (or bake potatoes) either.
Аноним 12/11/17 Вск 04:21:12 2764531
>>27599
Everything I mentioned is basically high school level material. Linear algebra itself is just a trivial case of module theory, which any even remotely smart person usually learns (by himself) in high school.
You should just look up the definition of (co)homology and try to prove the result yourself. It's almost trivial.
Аноним 12/11/17 Вск 08:01:20 2764832
>>27645
Second this.
>Linear algebra itself is just a trivial case of module theory
Or you can say the other way around, it doesn't matter.
"Linear branch" i.e. representation theory, homological algebra, etc, is about modules, essentially.
Аноним 12/11/17 Вск 12:56:24 2765733
>>27580
You can't. Every troll on this board will tell you that you can, but you're unable to. Consider this: you have two scalar products that lead to two different factorizations. Orthogonality is not what is inside the space, its all about product.
Аноним 12/11/17 Вск 13:06:24 2766234
>>27657
>You can't.
You can.
>you have two scalar products that lead to two different factorizations
Consider the category of modules over a field (or even free modules over a ring) with homomorphisms up to homotopy. You can easily show that any two factorizations are the same in this category.
Аноним 12/11/17 Вск 13:22:52 2766535
Аноним 12/11/17 Вск 13:32:50 2766836
>>27599
>doesnt know about cohomology
Thats why i love Russian education.
Аноним 12/11/17 Вск 14:08:29 2767037
>>27657
While it's still true that you cannot do it in general, in many particular settings it still possible.
For example, in the setting of functional vector spaces, which covers 99% of cases when infinite dimensional vector spaces appear, you always can construct a complement to your basis out of Barnett functions of this space.
Аноним 12/11/17 Вск 14:15:01 2767138
>>27668
In soviet translation of W. Rudin book "Real and complex analysis", in foreword, when desciribing prerequisite material, "undergraduate student" was translated as "high school student".
Starting from late 50's US education policy was to expel any mathematical education from every place, except grad school. And not even every grad school.
This was proved to be very wise decision.
Аноним 12/11/17 Вск 18:39:06 2767939
>>27513 (OP)
Let get it board forced, it will not force itself.
Аноним 12/11/17 Вск 18:52:53 2768040
>>27670
You probably mean Barnett-Sosnitsky functions.
It's still not known whether you can do in using just classical Barnett functions.
Аноним 13/11/17 Пнд 04:28:29 2769241
God dang it. Can we just add "homology" to the blacklist already?
Аноним 13/11/17 Пнд 04:31:12 2769342
>>27657
I don't really get what you're saying, man
Аноним 13/11/17 Пнд 06:01:44 2769443
Аноним 13/11/17 Пнд 07:47:55 2769644
>>27692
I agree. Might as well add any math terminology to the list while you're at it. It's not like this is a math board.
Аноним 13/11/17 Пнд 15:00:53 2771745
Аноним 13/11/17 Пнд 15:44:28 2771846
Аноним 14/11/17 Втр 10:00:00 2775547
Аноним 14/11/17 Втр 14:09:12 2778448
>>27620
>Mathematics is just a branch of algebraic k-theory.
But who needs this shit if operator k-theory is enough for the purposes of real mathematics?
Аноним 14/11/17 Втр 16:15:01 2778649
>>27784
Algebraic K-theory has many branches, one of them is 'real mathematics'.
Аноним 15/11/17 Срд 19:27:19 2785350
>>27784
>>27786
Why you still talk about K-theory? Is this mathematical board or something?
Аноним 15/11/17 Срд 21:21:25 2786151
>>27853
Looks like you didn't read board description.
>modules over rings, sheaves and cohomology
Аноним 16/11/17 Чтв 13:13:45 2790752
>>27861
And what relationship this have to mathematic?
Аноним 16/11/17 Чтв 13:24:24 2790953
>>27907
Much of mathematics arises as a special case of studying modules over a ring, sheaves and cohomology.
Аноним 16/11/17 Чтв 17:57:01 2792954
Аноним 18/11/17 Суб 22:34:50 2813355
OP : >>27513 (OP)

Hi. I have a problem. I am old and very slow.

I am proving theorems, solving problems from textbook, but it takes too much time.

How to boost my effectiveness?

I am writing proofs until they became absolutely clear.

Аноним 19/11/17 Вск 17:33:40 2819856
>>28133
You don't need to race it. Unless you want to sacrifice grasp for time.
Аноним 19/11/17 Вск 17:35:33 2819957
>>28133
>I am writing proofs until they became absolutely clear.
That's the best way to do it.
Аноним 19/11/17 Вск 21:15:33 2821758
>>28133
Why do you think you are slow in the first place? Since you've stated you're old, I'm guessing you have nobody to compare yourself to. I'd suggest continuing at the comfortable pace. No need to rush anyway.
Аноним 19/11/17 Вск 22:25:05 2822059
>>28217
>old
What's "old" in mathematics?
Аноним 19/11/17 Вск 22:42:57 2822160
Аноним 19/11/17 Вск 23:04:13 2822261
>>28221
Well, i don't know. Guru verbitsky saie it's about mid 30's.
Аноним 20/11/17 Пнд 01:16:51 2822862
>>28220
"Old" is a biological characteristic; it has nothing to do with mathematics per se.
Аноним 20/11/17 Пнд 01:41:16 2822963
>>27513 (OP)
> One exception: NO CYRILLIC SHIT ALLOWED IN THIS ITT THREAD!
Ты чё охуел?
Аноним 20/11/17 Пнд 02:08:15 2823264
Аноним 20/11/17 Пнд 08:23:43 2823565
>>28228
>>28222
Where? You probably misinterpreted him. First culture math was never about age, for example the index theorem alone took Atiyah and Singer nearly twenty years.
Grothendieck and his R&C and in correspondence with Serre, few times points out that it's not the age per se being restricted factor, it's your maturity as a mathematician.
The more inexperienced you are, the more oustanding and exceptional creations you are capable of.
Of course, in many cases, that maturity coinsides with senior age, but it doesn't have to.
It is generally believed, that you have to achieve something substantial in the first 10 years of career, after you completed your PhD. If that isn't happend in ten years period, it probably never will.
Аноним 20/11/17 Пнд 08:40:09 2823666
>>28222
In fact, Verbitsky explicitly said that one should prolong his study period as long as it feasible. Although that didn't happened with Verbitsky himself (he submitted his first paper at the age 17), his close ally, Kaledin did start his first research project around 28, if i recall correctly.
So they basically both say that late 20's – early thirties is ideal place to start doing math.
Combine that with already mentioned first ten years of special significance, and we're looking at late 30's – early 40's, just enough to get you Fields medal (every first-culture mathematician that I'm aware of, consider this award's age restriction as unnecessary discrimination).
Аноним 20/11/17 Пнд 09:49:33 2823867
>>28236
What area would you (and other anons) recommend for
>his (first) research project?

I am 30, I have background in math, I graduated and have been freelancing as an analyst/statistician, I continue to read recent papers on mathematical physics. I am very good at picking up things and self-education, from musical instruments and languages and drawing to algebraic topology and quantum field theory.

But it feels hopeless to provide any contribution to a field when you are on your own. I feel like I continue reading textbooks and papers just to "stay in form" and to run from the sad realization of wasting years of my life on shit I have zero opportunity to contribute to. I was always disillusioned by the romanticized image of a jack-of-all-trades scientist of earlier centuries, but it doesn't look viable or wanted in 2017. Especially modern math fields look bottomless and I could fuck around reading papers and textbooks 30 more years easily. Should I just give up?
Аноним 20/11/17 Пнд 10:41:40 2823968
>>28238
>Should I just give up?
You have to find PhD program in the field, that you're interested and then you need to find lab. Age is not a problem, until you're from China or used-to-be Soviet Union countries. Making papers in QFT (my point) on your own is very difficult task, unless you were involved in previous research. Making contribution to scientific community is almost impossible.
Аноним 20/11/17 Пнд 15:01:39 2824869
>>28236
>>28236
> Kaledin did start his first research project around 28
You mean after PhD?
Аноним 20/11/17 Пнд 17:09:33 2825370
>>28235
>First culture math
There is no other kind of math.
Аноним 20/11/17 Пнд 18:03:33 2825771
>>28238
I have several friends like you.
I also was in your situation.

I have enough experience and knowledge to recommend:
1) Do not quit your job.
2) Try attend evening classes in order to get a degree.
3) Solve problems. You should share solutions everywhere: boards, stackexchange, your classmates, your mentors. This should protect you from so-called Dunning–Kruger effect .

Аноним 20/11/17 Пнд 20:24:18 2826872
>>28238
Answering how to become mathematician professionally is easy: you just don't. Better say how did you become freelance statistician?
Аноним 21/11/17 Втр 13:12:55 2831173
>>28253
You go out on communication again?
Аноним 21/11/17 Втр 13:16:27 2831274
>>28238
Did you study music theory and composition or did you actually learned to play an instrument? If yes, which one and on what level?
Аноним 21/11/17 Втр 23:12:30 2833875
>>28253
What is the main difference between first culture and second culture? Which is first? Historical order?
Аноним 22/11/17 Срд 02:37:23 2834576
>>28338
>What is the main difference between first culture and second culture?
The main difference would be that one exists and the other doesn't.
>Which is first?
Well, there's only one, so clearly it would be first.
Аноним 22/11/17 Срд 11:20:01 2836177
>>28312
Both, it's hard to assess the level but I can improvise jazz beyond the standards and play by ear on guitar and piano. I really want to take up violin or a viola but they are pretty loud which is a no-go unless you have soundproofing (which I don't, and I don't want to disturb the neighbours). I started when I was around 15, so I had lots of time to improve - even without a teacher, you have to be retarded to not advance in a subject if you put enough time into it. I am constantly proving that, although the pointless nature of it all finally starts to catch up with me.

>>28268
Nothing compelling, unfortunately, as it all boils down to modern trends of big data analysis or simple econometrics.
Аноним 22/11/17 Срд 13:43:37 2837978
Аноним 22/11/17 Срд 17:20:36 2839979
Аноним 22/11/17 Срд 20:16:01 2841480
>>28399
He meant how can one compute the cohomology of a box product.
Аноним 22/11/17 Срд 20:18:52 2841581
>>28414
Obviously by taking cohomology of the n-fold loop space.
Аноним 22/11/17 Срд 20:25:24 2841682
>>28399
Box for sand from plywood.
Аноним 22/11/17 Срд 20:29:30 2841983
>>28399
The box.

>>28361
I started around the same age, and I still can't really improvise. It's true that I'm advancing with time, elthough slowly, but I feel like it's a bit pointless too. I have an impressions that I've accomplishied more in my teen years, more specifically in half-a-year or so when I was practicing like 5-6 hours a day, than in all the years passed since. The shapes and sounds (just diatonic, eh) I've studied then are engrained in my brain, and everything just happens. Now I'm practicing a couple of times a week, and I feel like I'm just not going anywhere. I have to remember what I studied last time when I pick the instrument - even if that's the same thing I've been studying for the entire month. Obviously, it can't not affect my motivation, so I'm practicing mostrly because I've used to it, without any particular goal or results.

Interestingly enough, the sounds I listened to (as opposed to practicing) in my teen years are still with me so to speak - they've become my second nature too, just like the basic major scale shape, and I can hear it any time in my brain, but I can't actually produce it and improvise with it. Disconnect between intuition and technique/knowledge is astonishing, and is quite a bummer.
Аноним 24/11/17 Птн 04:57:38 2849684
Аноним 24/11/17 Птн 16:29:16 2850985
>>28496
You should learn the memes in order to not be a butthurt.
Аноним 25/11/17 Суб 09:27:24 2853486
How can one compute the cohomology of an R-module?
Аноним 25/11/17 Суб 15:42:17 2857487
>>28496
Solve this problem.

You work keepers-handyman in kindergarten.
One day superiors give you a task, create box for sand volume 40 liters in case of fire.
You have enough plywood to do it, but since you work keepers-handyman in soviet russia you must economize plywood consumption, or you get fine for embezzlement and action in court.
Seat for box that you must use is in the corner, so box must have cuboid form with square base. What dimensions of the box surface you must cut to satisfies all conditions?
Аноним 25/11/17 Суб 16:12:25 2857788
>>28574
>What dimensions of the box surface you must cut to satisfies all conditions?
4 (up to unique isomorphism)
Аноним 25/11/17 Суб 21:07:00 2859789
>>28574
n-metric sphere, with n -> inf.
Аноним 25/11/17 Суб 21:10:59 2859890
>>28574
Little fix for you

>since you work keepers-handyman in soviet russia you must economize plywood consumption, becouse its only piece of plywood that you have for next 5-7 years on the budget.
Аноним 26/11/17 Вск 05:25:00 2863591
>>28574
Any space homotopy equivalent to an n-sphere with n being a rational number.
Аноним 26/11/17 Вск 22:06:44 2878892
Аноним 21/01/18 Вск 12:49:43 3538793
Аноним 21/01/18 Вск 16:24:53 3547794
Аноним 21/01/18 Вск 17:20:40 3557595
>>35387
no brother you are to me, black-assed gneedah.
Аноним 09/02/18 Птн 21:19:07 3651096
huya u vas tut ozivlennost portovogo goroda
Аноним 10/02/18 Суб 00:48:53 3653497
soglasen. kruta tut ya shitayu.
Аноним 20/03/18 Втр 13:28:54 3773098
>in this ITT
>ITT
Аноним 20/03/18 Втр 16:22:14 3773199
>>37730
You're here for not such a long time, aren't you?
Аноним 08/12/20 Втр 15:44:22 77006100
Hello, fellow Niggers! Did you hear about Church -Turing thesis? What do you think 'bout it?)
Аноним 26/02/21 Птн 21:22:50 80801101
I'm newbie and want to start my journey in math with this book. Is that a good choice?
Аноним 27/02/21 Суб 10:30:52 80815102
How can you make math in Russia whereas Russia is a shithole?
Аноним 27/02/21 Суб 20:07:37 80844103
>>80801
I doubt that. Discrete mathematics is not mathematics at all. Not to mention its applications
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