Mathematics - 2024-06-13

HighAsAKiteOnMath

00:38

@mick you around?

Xander Henderson

01:11

This guy! math.stackexchange.com/a/4929836

Thorgott

01:36

that's a lot of words to say something entirely circular

one potato two potato

03:47

\

user 85795

/

Zophikel

12:47

@XanderHenderson btw did you what you wanted to research when you entered graduate school ?

Currently it's looking my plans are achievable since I might be getting a older gf that is willing to help out with education expenses :)

Xander Henderson

@Zophikel My path through higher education should not be emulated.

Zophikel

@XanderHenderson i'm aware :( my current job has nice education benefits and they even encourage us to do masters and they have programs for people looking to go to graduate school

It's just that I wanted to explore math/physics a bit more in depth before heading back

Xander Henderson

In general, I think that it is a bad idea to enter graduate school with a research agenda. Instead, you should be thinking about people with whom you can get along. But you aren't going to know who those people are until you get there. So apply to programs, look at who's there before you arrive, but be ready to work with anyone on anything, as long as you are compatible and get along well.

Contrary to that advice, I started my PhD program with a fairly good idea of what it was that I wanted to do---essentially, I wanted to extend some of the work I had done in my masters program (which is what I ended up doing).

Zophikel

@XanderHenderson that makes sense but for now my main focus is just to learn more some of these online uni's have a very nice course selection like John Hopkins has the entire grad sequence for Physics online

ASU has the entire undergraduate sequence and my home uni as a decent selection of math's course at the advanced undergraduate level

Xander Henderson

Even then, when I applied to the program I ended up in, there were two faculty who, on paper, I wanted to work with. And when I get there, there was a third faculty I almost ended up with.

@Zophikel Arizona State? their online school?

Avoid their online school.

In general, just avoid ASU.

Zophikel

12:54

What's wrong with ASU ?

Xander Henderson

They have been expanding a lot recently, and ABOR hasn't been on them to maintain quality standards. They have a lot of programs offering degrees which aren't really worth the paper they are printed on.

Their in-person offerings are... fine (though U of A is a lot better if you are going to be in Arizona---I almost did my phd there; they have a solid applied mathematics program, and their optics and materials people work with NASA and JPL).

Zophikel

I'm not aiming to get a degree online but just to get more courses to learn more

Lemme check them out

Xander Henderson

@Zophikel Online classes---particularly in the upper division---aren't that great. Personally, I would be suspicious of a middling transcript followed by a bunch of online classes to boost the GPA (if I were on an admissions committee).

Of course, you also have to understand that one of my brothers, one of my sisters, and both of my parents have degrees from University of Arizona (my brother has a BA and JD, my sister a BS, my mother an MA, and my father a PhD and JD). I have another sister with a degree from Northern Arizona (an MA), and I work at a community college in Arizona (where I work with representatives from all of the colleges and universities on articulation---ASU is... special in that regard).

Zophikel

@XanderHenderson like the places that offer these courses are like uni's like IU Bloomington and John Hopkins tho

Xander Henderson

I'm a bit biased against ASU.

F those guys. :D

BEAR DOWN!

Zophikel

13:00

Like the uni's aren't diploma mills but I can understand where your coming from @XanderHenderson

Xander Henderson

Honestly, I fear that ASU's online programs are maybe a step above diploma mills. I mean, they aren't Southern New Hampshire, nor University of Phoenix, nor even Grand Canyon... but I'm not impressed by ASU's online offerings.

Zophikel

@XanderHenderson I mean if I was in EU I would just go in person to their taught course centers or nearby institutes

The issue is my uni won't let me transfer in credits from outside universitys

Xander Henderson

But why do you need them to transfer?

As I recall, your goal is to take enough classes to make yourself attractive to graduate school admission committees.

Zophikel

Yeah and I also will need to meet the gpa requirements as well

Xander Henderson

The GPA "requirements" really aren't hard-and-fast, and a good cover letter will explain the transcripts.

Zophikel

13:05

True but with how competitive things have gotten and with the rejections I've seen I want to be prepared

@XanderHenderson but is ASU's online offferings that bad tho ?

Xander Henderson

"My undergraduate GPA wasn't great, but after graduating, I discovered my passion for mathematics and started taking more classes on my own time. Since graduating, I have taken several classes, such as [really hard class] and [another really hard class], earning As in all of them."

Zophikel

@XanderHenderson I can send you the list of some of the uni's i'm looking at

Xander Henderson

@Zophikel That depends very much on who is reading your transcipts.

Zophikel

@XanderHenderson give your insight what makes ASU so bad ? The reason I was intrigued was besides JHU they were offering the Physics sequence

Xander Henderson

Honestly, I think that the best advice I can give you (because this did work for me) is to (a) take classes locally, (b) build relationships with the people at your local institution, and then (c) apply to a masters program at your local institution, using your local network to help your application along.

Zophikel

13:08

@XanderHenderson I was aiming to do that but I had move out of state for my tech job there no jobs in my home state

Xander Henderson

@Zophikel Like I said above, they have expanded out their online offerings, but haven't really done what they need to do in order to ensure that the quality of their online classes is maintained. They have hired a bunch of adjuncts, and the online sections can be huge. If I am reading an application packet, I am going to be suspicious of any online program, and I am familiar enough with ASU to know that they aren't doing anything special.

@Zophikel Yeah, but where ever you are, there should be some local university. There are some places in the US where there may not be, but not many.

Zophikel

@XanderHenderson best local uni to me is OSU but with the financial support I'll be getting it's worth it for me to attend in person while fixing my gpa while remotely enrolled at my home uni

But I can understand why an admissions committee would be suspicious regarding just purely online courses

@XanderHenderson what I could do is after grinding some more advanced undergraduate math courses just come in person to my local uni catalog.okstate.edu/courses/math

@XanderHenderson the reason why I started thinking of doing online for a bit was because of the wide course selection at a place like ep.jhu.edu/programs/applied-and-computational-mathematics/…

JHU also offers in person as well

Xander Henderson

Isn't David Ullrich at OK State? He's pretty active here.

s.harp

13:24

@XanderHenderson The MSE user? I thought he passed away.

Zophikel

183

Q: User David C. Ullrich and long-time sci.math participant died 22 March 2024

By accident -- I don't even remember what I was originally searching for -- I just learned that user David Charles Ullrich (2642 answers in Mathematics Stack Exchange; Mathematics Genealogy Project entry; reviews of his publications at Zbl; 1981 Ph.D. under Walter Rudin) died just over 2 weeks ag...

discussion

I think he died

Xander Henderson

Oh, yeah. :/

I remember that.

Gosh... twice in two days I've thought that dead people are still alive. I must be getting old. People are dying off around me. :(

Zophikel

@XanderHenderson I mean my plans aren't completely terrible the uni's i'm looking at are reputable and the air force will have me traveling so i'll be going to a bunch of places

s.harp

@XanderHenderson Maybe a similar reason was the motivation for Michel Talagrand to create a list of his dead friends (dont know why he put it on his website though) michel.talagrand.net/friends.pdf

Xander Henderson

In any event, I am not getting my grading done sitting here at home---I am going to head into the office, ignore you all, and do some actual work.

Zophikel

13:27

Have fun :)

Jakobian

Sterile insect technique

The sterile insect technique (SIT) is a method of biological insect control, whereby overwhelming numbers of sterile insects are released into the wild. The released insects are preferably male, as this is more cost-effective and the females may in some situations cause damage by laying eggs in the crop, or, in the case of mosquitoes, taking blood from humans. The sterile males compete with fertile males to mate with the females. Females that mate with a sterile male produce no offspring, thus reducing the next generation's population. Sterile insects are not self-replicating and, therefore, cannot...

pretty cool

Xander Henderson

14:44

Ugh... I HATE online classes. I have 12 students currently enrolled. Only three of them turned in the first exam. One of the 9 remaining students emailed me on Monday for an extension (they didn't get enrolled into the class until the end of week 1, so that seemed fair). But what about the other 8?!

nickbros123

@XanderHenderson one thing about india is that everything is based on paper, rules etc, not based on personal interaction. if u dont turn in the exam, you just fail.

Xander Henderson

@nickbros123 I mean, that is what is going to happen here, too.

s.harp

@XanderHenderson What do you do in this situation? Just have them fail and try again next year?

Xander Henderson

(Though I will probably drop those students, rather than give them Fs).

@s.harp Yes, more or less. Students who don't complete work can be dropped from the class. It isn't a "fail", it is a "you never showed up". Dropping a student from the class does not hurt their GPA.

s.harp

15:00

Then it works out for you in the end, since now you only have 4 students whose work you need to check :)

Xander Henderson

@s.harp How cynical.

I really prefer to have more students. :/

Jakobian

More people to yell at, eh

psie

15:15

> Problem: Let $A\subset \mathbb R^n$ be an open set and $f:A\to\mathbb R^n$ a continuously differentiable injective function such that $\det f'(x)\neq 0$ for all $x$. Show that $f(A)$ is an open set and $f^{-1}:f(A)\to A$ is differentiable. Show also that $f(B)$ is open for any open set $B\subset A$.

My question; is showing $f(A)$ is open redunant? If $f^{-1}$ is continuous and $A$ is open, then by continuity...

Jam

I have fireld extention where the minimal polynomial divides this polynomial $64x^7-112x^5+56x^3-7x-7/8 $ .What can i say about the degree of the extention?

extension*

Xander Henderson

@psie Nope. The preimage of open sets are open. That says nothing about the image of an open set.

Oh, you are assuming that $f^{-1}$ is continuous.

It seems that you are being asked to prove that...

psie

yeah, and then it follows that $f(A)$ is open, right?

This is from Spivak's book, by the way.

Oh, I realize something stupid.

I have a typo.

No wait

It is correct!

Apologies.

Xander Henderson

Apologies---I am in the middle of grading, and probably shouldn't be trying to interact here, too. Laters.

Jakobian

15:34

@psie this is true without assumption of differentiability and is called invariance of domain

but the proof that $f(A)$ is open is easier when $f$ is differentiable

psie

I realize I do need to show $f(A)$ is open, in addition to showing $f^{-1}$ is continuous.

Jakobian

@psie no its not redundant. If $f^{-1}$ is continuous, that doesn't mean we can define what it means for it to be differentiable

because it doesn't have to be defined on an open set...

ah. Continuously differentiable, yes. The proof when $f$ is only differentiable is also harder

@Jakobian continuously differentiable, even

psie

how about this? for every $y\in f(A)$, there is an $x\in A$ with $f(x)=y$. By the IFT, there is an open set $U\subset A$ and an open subset $V\subset\mathbb R^n$ such that $x\in U$ and $f(U)=V$. Since $y\in V$, this shows that $f(A)$ is open

Jakobian

15:56

@psie yes

psie

cool 👍

Mats Granvik

$1=\underset{n=1}{1}+\underset{n>1}{0}$

s.harp

Funnily enough the conclusion of $f$ being an open map holds even if you drop the differentiability condition

Xander Henderson

16:34

One student just got back to me "Oh, I thought I'd already done it! Can I have an extra day?"

Which, okay, fine, take an extra day. What do I care. But, like PAY ATTENTION TO THE DEADLINES!

X(

s.harp

what does it mean: I thought I'd already done it, when we are talking about an exam?

Xander Henderson

@s.harp It is an online class. There is a window of time in which they must complete the exam.

Sadly, we don't meet in person.

I'm imagining something like the following:

Monty Python-Killer Rabbit

►

double-beep

16:59

I'm asked to determine whether $\displaystyle{\int_0^{\infty} x^3 e^{-2x} \cos x} \, \mathrm{d}x$ converges. Would this solution be correct? Since $x^3 e^{-2x} \cos x < e^{-x}$ for $x > 0$, it follows that $\displaystyle{\int_0^{\infty} x^3 e^{-2x} \cos x} \, \mathrm{d}x < \displaystyle{\int_0^{\infty} e^{-x}} \, \mathrm{d}x = 1$, therefore the integral converges.

Jakobian

@double-beep no

this is wrong

let me ask you this, how do you know the expression $\int_0^\infty x^3e^{-2x}\cos x \ \mathrm{d}x$ makes sense?

double-beep

@Jakobian so I must first ensure that the limit exists, right?

Jakobian

what limit?

be precise

double-beep

$\displaystyle{\lim_{t \to \infty} \int_0^{t} x^3 e^{-2x} \cos x} \, \mathrm{d}x$

Xander Henderson

@Jakobian The question is (in my opinion) poorly phrased, but as I see it, that is exactly what is being asked---determine whether or not the expression "makes sense": does the limit which defines the integral converge? (which is often shortened by lazy authors to "Does the integral converge?")

Jakobian

17:08

@double-beep this is what it means, at least in the improper Riemann integral sense, for the integral to converge

double-beep

yes, that's what I meant with "limit"

Jakobian

if you mean that you need to show it directly, no you don't need to

Xander Henderson

@double-beep The argument is basically fine, but not quite right. For example, $-x < \mathrm{e}^{-x}$, but $\int_{0}^{\infty} -x \,\mathrm{d}x$ does not converge. You are missing something important here.

Jakobian

basically fine is not how I'd put it...

the correct solution would be similar, but that doesn't make it basically fine in my opinion

@XanderHenderson makes sense, because I am counting value of $\pm \infty$ as making sense

Xander Henderson

Yes, I know @Jakobian. But when you grade a student's work, it is best to start from a place of helpfulness and optimism, rather than to just crush them right out the gate. The underlying reasoning presented is basically the right idea, but the formal presentation needs work. This is common for students who are just learning how to speak the language.

Jakobian

17:11

this is also in tandem with the next point I was planning to make

the question was, is my solution correct, this is what I answered. shrug

Xander Henderson

And the basic argument is correct: the integrand is bounded by something integrable, so the integral converges. There are several problems with how this underlying intuition has been formalized by the student, but the correct idea is there (the argument is basically fine, the exposition is off).

Jakobian

> the integrand is bounded by something integrable, so the integral converges

that's incorrect and its what I'm trying to write here

correct here

double-beep

@XanderHenderson this? $\int_0^\infty x^3 e^{-2x} \cos x \, \mathrm{d}x > \int_0^\infty -e^{-x} \,\mathrm{d}x$

Xander Henderson

@Jakobian Okay... whatever.

Jakobian

and anyway I think the correct thing to do is mention that something is incorrect and then correct it to show how its done

Xander Henderson

17:18

@double-beep Sure, or $|x^3 \mathrm{e}^{-2x} \cos(x)| \le \mathrm{e}^{-x}$. Better to work with the integrands (which you know "exist" and have the properties that you want) than to work with the integrals (which may not "exist" or have the properties you require).

Jakobian

instead of arguing about it

double-beep

17:44

@XanderHenderson what about $\int_0^\infty x^3 e^{2x} \cos x \, \mathrm{d}x$? Could I use something similar to prove that it does not converge?

Xander Henderson

@double-beep Maybe? What do you have in mind?

For what it is worth, however, I think it is simpler to just note that the integrand doesn't go to zero. If the integrand doesn't go to zero, then how can the limit defining that improper Riemann integral converge?

(It is possible for an integrand to fail to go to zero, and for the integral to still converge---so the question is a genuine one which needs to be answered; but in this particular case, there is an argument which starts from that point of view, and then shows divergence).

double-beep

18:02

@XanderHenderson if I prove that $\displaystyle{\lim_{x \to \infty}} (x^3 e^{2x} \cos x)$ does not exist, does that mean that the integral does not converge?

Sine of the Time

@double-beep no

Jakobian

@double-beep But if you find $s_n < t_n$, $s_n, t_n\to\infty$ such that $\int_{s_n}^{t_n} x^3e^{2x}\cos(x)\ \mathrm{d}x$ does not converge then the integral does not converge

an example of what @SineoftheTime answered is $\sin(x^2)$, here $\int_0^\infty \sin(x^2)\ \mathrm{d}x$ converges but $\lim_{x\to \infty} \sin(x^2)$ doesn't exist

Xander Henderson

@double-beep Not necessarily, no. But the fact that oscillates with increasing amplitude should be suggestive.

Sine of the Time

18:18

if $\int_a^{+\infty}f(x)\mathrm dx<+\infty$ you can't conclude that $\lim_{x\to+\infty}f(x)=0$

double-beep

@Jakobian how would I find whether $\int_{s_n}^{t_n} x^3 e^{2x} \cos x \, \mathrm{d}x$ converges or not?

Jakobian

@double-beep sorry, I mean convergence to $0$

the idea is to choose $s_n, t_n$ so that $\cos(x) > 1/2$ on $[s_n, t_n]$ lets say

this follows from that $\int_0^{t_n} x^3e^{2x}\cos x\ \mathrm{d}x - \int_0^{s_n} x^3e^{2x}\cos x\ \mathrm{d}x = \int_{s_n}^{t_n} x^3e^{2x}\cos x\ \mathrm{d}x$ would converge to $0$ if this integral were convergent

you can say, then, that for example $\int_{s_n}^{t_n} x^3e^{2x}\cos x\ \mathrm{d}x > \frac{t_n-s_n}{2}$

but you can choose $t_n-s_n$ to be a constant positive number

because of how cosine is periodic

Tinkeringbell

19:01

Jakobian that last bit really wasn't necessary.

double-beep

19:13

@XanderHenderson nothing in particular, the problem stated: "Prove that $x^3 < e^x$ for big enough x > 0. Then, determine whether <integral> converges"

@Jakobian thank you for your help

nickbros123

some properties of natural numbers rely on the structure of its bigger field which is reals. that seems really strange but also cool

is it like, we cannot separately talk about natural number set, but only like the subset of reals

s.harp

Heres a little question: How can you calculate an expression like $\frac{\binom{100}{50}}{2^{100}}$ to a reasonable degree of accuracy (like ~10%) without using a computer/calculator in a reasonable amount of time (ie without carrying out 25-50 multiplications)?

I'm asking out of curiosity and I do not have much of a strategy myself

Soumik Mukherjee

19:40

@nickbros123 like?

Jakobian

19:50

@s.harp there is some info on wikipedia here

it seems like this is approximately $\frac{1}{\sqrt{\pi n}}$ where $n = 50$

which is around 0.0797884

the error here is less than 0.001

Semiclassical

you can definitely do some stirling approximation business

@s.harp and actually, computing $\binom{2n}{n+x}/\binom{2n}{n}$ for $|x|\ll n$ is a calculation that shows up in introductory statistical mechanics frequently

Jakobian

yeah, I think $\frac{1}{\sqrt{\pi n}}$ is what comes up with just your standard Stirling approximation

s.harp

Those are good approximations

The motivation for the question was that VI Arnold had written somewhere that if you cant compute the integral of sin^100 from 0 till 2pi to 10% accuracy in less than 5 minutes you werent allowed to call yourself a mathematician

Jakobian

Isn't Arnold the one that also thinks physics and mathematics should be the same, or something of the sort

s.harp

doing a trick with a complex integral you can reduce the integral to calculationg 1/(2pi) * (100 choose 50) / (2^100)

@Jakobian he may have said something of the sort, he had strong opinions on many things

Jakobian

20:05

Yeah I don't think I want to take him seriously. From what I heard there are experts on algebraic topology out there that barely know how to integrate

leslie townes

that's also a very soviet thing to say, haha

s.harp

another arnold classic:

Jakobian

I think Arnold is stating that he has really high standards rather than trying to be correct

leslie townes

i mean i expect VI arnold would have been like that wherever he was educated, but "increasingly escalating series of brain teasers under a time limit, paired with challenge about how people who can't solve them are undeserving" is very soviet

that's basically how they kept 'undesirable' students out of their university system

s.harp

@leslietownes here is a document by Arnold that does precisely that, its bound to put the heat on almost anybody physics.montana.edu/avorontsov/teaching/problemoftheweek/…

leslie townes

20:14

you could probably write a funny soviet era comedy about a person who is tasked with designing the oral exam that keeps VI arnold out of university

Jakobian

@s.harp I think this is just Taylor approximations but I don't know tan Taylor series by heart

s.harp

@Jakobian thats what I would try as well, the question is how many derivatives you need to use

Jakobian

ah, because tan Taylor series involves some $B_n$ numbers which I think are Bernoulli numbers, which I also don't really know

s.harp

@Jakobian use tan' = 1+tan^2 to manually calculate the derivatives, thats what id do atleast

Jakobian

I think most of this exercise I'd spent on just calculating them

or I could substitute tan(x/2)

leslie townes

20:21

i find it all kind of disappointing, it is a very 19th century, aristocratic, exclusionary view of what is worth knowing. it's only in subjects like math that people are more willing to confuse this kind of perspective with some kind of insistence on a high standard. if you complain about how nobody reads aristotle in the original greek anymore (or whatever), people just (rightly) roll their eyes

it's a nice problem though

arnold was also a really good lecturer and not just a merchant of hot takes

Xander Henderson

@leslietownes Seems like you are saying that Arnold needs to get woke.

:P

leslie townes

xander: well, i'm actually willing to listen to that stuff from arnold, but not from, like, professor X at whatever university, let alone some rando

s.harp

@leslietownes what ive read of his books is a combination of deeply frustrating, insightful, really well written, and really badly written

Xander Henderson

@leslietownes Hey... I'm Professor X!

leslie townes

the problem with those takes isn't so much that arnold has them, but that they greatly appeal to randos

xander: haha an unfortunate coincidence

Jakobian

20:27

@s.harp I think that's what Fichtenholz does

s.harp

@Jakobian who is that?

Jakobian

An author of a really popular series of books from analysis

known only in Europe because there is no translation into English

s.harp

@Jakobian ah, you mean to calculate the power series of tan? or to solve the problem

Jakobian

to calculate the derivatives, yes

Grigorii Fikhtengol'ts

Grigorii Mikhailovich Fikhtengol'ts (Russian: Григо́рий Миха́йлович Фихтенго́льц, Ukrainian: Григорій Михайлович Фіхтенгольц, romanized: Hryhorii Mykhailovych Fikhtenholts; 8 June 1888 – 26 June 1959) was a Soviet mathematician working on real analysis and functional analysis. Fikhtengol'ts was one of the founders of the Leningrad school of real analysis. He was born in Odessa, Russian Empire in 1888, and graduated Odessa University in 1911. He authored a three-volume textbook titled "A Course of Differential and Integral Calculus". The textbook covers mathematical analysis of functions of one...

Tsundoku

@Jakobian This Fichtenholz?

Jakobian

20:30

he was half German

leslie townes

with a beard like that, you know his analysis books are going to be good

Xander Henderson

@leslietownes To be fair, I am not actually a professor---my job title is "Faculty of Mathematics". Most American academics don't really care about the distinction, but my advisor was French.

Tsundoku

Well, his name literally means spruce (wood) in German.

It would have been worse if you advisor had been German. You need to be at least Prof. Dr. Dr. to count for anything in German academia.

s.harp

Prof Dr Dr Habil Debil

Tsundoku

There's also Prof. Dr. h.c. mult.

leslie townes

20:34

and in the corporate world you couldn't rest until you were the vice president of something

Jakobian

maybe there is actually a translation of his books into English, last time I checked I could have sweared there wasn't an English version

anyway, his books are really praised, and the first volume of his series on analysis is what I started with

Xander Henderson

@Tsundoku Indeed.

Jakobian

@s.harp Debil means an idiot in many Slavic languages

maybe you intended that

Tsundoku

@Jakobian Not only in Slavic languages, for that matter.

Jakobian

@Tsundoku what languages do you have in mind?

Tsundoku

20:38

Dutch ("debiel"), French ("débile").

Jakobian

I see, I didn't know that

it makes sense, its from Latin

Tsundoku

Exactly ("debilis").

What are the prerequisites for Fichtenholz's first volume on analysis?

Jakobian

there aren't any, I started to read it when I was very young

I didn't finish it at that time, but there really are no prerequisites from what I recall

Tsundoku

Well, surely there must be something? Like basic algebra and perhaps trigonometry?

Jakobian

Yeah there are trigonometric functions, I don't believe they ever get explained, but even if you jump into it without prior knowledge there is a lot to gain from it

s.harp

20:45

@Jakobian yes it was a joke

Jakobian

I don't have a copy of Fichtenholz on me right now, but its good to have familiarity with what I'd call the basics that you learn in high school (like basic algebra and trigonometry)

Tsundoku

It turns out that the German translation of Differential- und Integralrechnung is on Archive.org, so I can check how he approaches the subject.

Jakobian

21:08

there is this movie, The Imitation Game, but its sad that they're not talking about how Turing only expanded the work of Polish mathematicians Zygalski, Różycki and Rejewski

they were the ones that "broke" the Enigma, not Turing

so this is basically propaganda

the British did mass produce the slightly improved machines that Turing came up with, yes, but this was still because of the work of Polish mathematicians

apparently there was another movie about Turing where they did the same thing with neglecting the role of Polish mathematicians in the war

leslie townes

21:24

i dunno about 'propaganda,' it's the stuff about other people that movies usually cut out of a dramatized biography of one person. modern english language books about that history usually get it right

older books (say before 1990) also suffer from the authors not always having ready access to relevant sources because governments were still classifying that stuff or making it hard to access

Jakobian

That's reasonable but I can't give it to the directors of this movie, they should know better than this

leslie townes

so there is maybe a tendency to hype what you have access to

i wasn't planning on seeing it either way :)

Jakobian

I think this might even count as cultural appropriation

s.harp

@Jakobian are you saying that cracking nazi codes is a polish cultural tradition that turing appropriated?

Jakobian

@s.harp yes. This is very traditional in my country

jokes aside, okay I know this is not quite "culture" but it is an achievement, and for Polish people not only of those mathematicians, but for the country itself. I don't know how else would I call it

but maybe it is culture... hmm

Jakobian

21:52

@leslietownes actually from what I read, the British are trying to (or at least tried in the past) consistently attribute this to themselves so this might only be half the truth.

according to my sources up to 1999

and The Imitation Game is based on a book from 1983

anak

Suppose I have a submanifold $i\colon N\hookrightarrow M$ and an exact $k$-form $\omega$ such that $\omega|_N = 0$ which is in both in the both the relative cohomology class of zero. I am told this implies $\omega = d\beta$ for some $\beta$ such that $i^*\beta=0$, but I am unsure about the pullback part. From the relative cohomology being zero I easily get that $\omega = d\beta$ and $i^*\beta = d\theta$ for some $\theta\in\Omega^{k-2}(N)$...but I am unsure how to proceed.

leslie townes

jakobian: okay, i have to ask, what happened in 1999? :)

Jakobian

22:15

@leslietownes its actually not written here, I don't know why they stopped attributing it to themselves in 1999.

Its oddly specific

leslie townes

i mean, i would take any claim about what 'the british' are trying to do for 'themselves' with a grain of salt. it wouldn't surprise me if individual authors were deliberately or unwittingly nationalistic

i was using 1990 above as a kind of arbitrary dividing between 'modern' and 'older' because it's about 50 years after WW2, and 50 is not only a round number but one sometimes used by actual governments as a default term for classification to expire

with anything crypto i can imagine some governments selectively declassifying earlier to win PR and selectively withholding other stuff beyond a default because they think its important or they just like holding secrets

so it wouldn't surprise me if something written in 1983 were manipulated, even if it wasn't the author's intention (which of course maybe it was)

now we have a mystery of 1999 to solve

Jakobian

actually there was a book written in 2014 which also didn't mention the achievements of Polish mathematicians, so this still happens

by Andrew Hodges

apparently he is a mathematician that worked with Turing but he also didn't mention the great contribution of Polish mathematicians in breaking of Enigma...

leslie townes

there might be something of a british cultural tradition of ignoring the polish :D if you read the history of 1930s england and france etc. did not pay as close attention to polish intelligence about what the nazis had and were going to do, and some of the info about the progress of the holocaust in poland was maybe not taken as seriously as it would have been if it came from english or french sources

as one guess at the 1999 mystery, british pop sci author simon singh wrote "the code book" in 1999 and it discusses the polish contribution :)

anyone who actually worked with turing and was writing in 2014, you'd wonder about the state of their memory

even a lot of immediately post war sources for stuff (not so much crypto but military history) are often clouded by people not having access to the stuff they had in the war, or only getting pieces of it back from their governments

i suppose it's conceivable (i don't know how plausible this is) that someone working with turing might not even known of where some of the stuff they were improving had come from

Jakobian

I'm hoping to, if I survive to 70's, to have better memory due to me studying mathematics, but that might be completely irrelevant, I don't know

leslie townes

22:31

like, it stands to reason that someone working on government crypto stuff in 2024 is probably not always being told where their stuff is coming from, and might even be told less about it than someone not working for a government would know, so maybe there is no need to presume that any "first hand witness" working at a government agency is actually a better source on the history than a historian decades later would be

Semiclassical

@Jakobian it'd be rather difficult for them to have worked together: Hodges was 5 years old when Turing died :P

Hodges' work in math was under Roger Penrose and dealt with twistor theory. in particular, he's the guy behind this website: twistordiagrams.org.uk

Jakobian

ah sorry. They said "kolega po fachu" which means like a friend by field of work. But they meant he was also a mathematician

sorry, sorry, thanks for correcting me

Semiclassical

in principle they could have met, but it'd be a hell of a coincidence

my knowledge of this stuff is largely via Budiansky's Battle Of Wits, which does cover the Polish contributions

Jakobian

sorry for changing the topic, but I just found about the Kaaba and I find this so bizarre

anak

23:06

@Jakobian Which one? He wrote the one that The Imitation Game was based on, but that was in the 80s

Semiclassical

@anak "based on" is doing a lot of work from what i understand

anak

@Semiclassical As always, mathematical dramas diverge from source material.

Semiclassical

yeah, but the degree to which it just Made S*** Up crossed a line imo

(i mostly have in mind Christian Caryl's essay at the time: nybooks.com/online/2014/12/19/poor-imitation-alan-turing, paywalled alas)

anak

12ft.io it

Semiclassical

this is a good summary of my beef: "Films reach more people than books. So statistically speaking, most of what you know about Bletchley Park probably comes from the Oscar-winning film The Imitation Game. This gives us a starting point: the film is a bad guide to reality but a useful summary of everything that the popular imagination gets wrong about Bletchley Park." source

anak

23:36

I also did not like "The Man Who Knew Infinity".

Peter

A thumb rule in films , songs , books , etc. , considering the bizarre taste of the big audience is that it is probably a good idea to concentrate on the ones with a smaller audience , because they are probably better ! The catch is sadly that those films, songs , books , etc. do barely appear and are almost impossible to get.

anak

I really liked the documentary "Secrets of the surface", it was excellent.

Semiclassical

this is not an assessment of the film's artistic qualities, mind---it could be excellently crafted and i'd still have a problem with it

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