Mathematics

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Tue 09:45
@anankElpis yeah, fair point. Ill have to think about this; the paper is really tough to comprehend for me tbh, I am severely lacking in prerequisites, but I can spend a few months building just the prereqs. I think perhaps I will try to digest atleast a few pages of the paper (post building the prereqs) before I decide to drop it and ask him for a different topic
Tue 09:29
but its also possible I end up liking number theory and turn it into my thesis area.. its all a bit confusing/unclear at the moment
Tue 09:27
he didn't really have me in mind when he chose the topic per se. I needed to do a minor project for credits (minor being physics) and I approached him for something; it was just math he wanted to understand earlier, but he didnt spend much time on it before, so he figured now is a better time than any, so he thought he would give me this paper to read, and present it to him and his cohort.

The applications that he cares about are in string theory, certain counting problems in black hole physics and so on, but my work isnt in physics, I just have to understand the math that goes into it- mo
Tue 05:40
before I ask this question, a bit of background: Im in my 4th year in a 5 year BSc+Msc in mathematics, and my 5th year is the final project year.

Now, a physics prof has (surprisingly (?)) given me some rather interesting reading work in number theory, that will effectively take up around 9 months (its to do with modular forms / mock modular forms, jacobi forms, hecke operators etc), and I know very very little number theory so it will demand quite a bit of my time. Now I am not entirely sure if NT will be my interest of masters thesis topic, it might be some other field, maybe functional
Jun 30 07:34
measure theory proves to be hard; but perhaps its my own undoing, trying to read it in a month
Jun 20 08:56
@Jakobian sigh
Jun 20 08:00
@Jakobian by getting a proof
Jun 20 07:31
@Jakobian no reason, just wondering if its possible to generate another proof
Jun 20 06:48
some tinfoil hat speculation incoming:

we know via some fact about the natural numbers that for any field $F^{\infty}$ is uncountable dimensioned. Suppose $U$ is a subspace such that each sequence in $U$ only has finite non zero coordinates. The first fact would show that $F^{\infty}/U$ is infinite dimensioned, (since if it were finite, $F^{\infty}\sim U \times F^{\infty}/U$) via some cardinality argument.

My question is, could I reverse engineer this proof in some fashion such that I begin with the fact that $F^{\infty}/U$ is infinite dimensioned (I can generate an infinite linearly inde
Jun 19 15:18
like, that was the first time i tried meat
Jun 19 15:17
@XanderHenderson maybe ur right, im new to meat lol
Jun 19 15:13
@XanderHenderson lol, it was good im not gonna lie, so its worthy of some hype ofc
Jun 19 15:10
@XanderHenderson i didnt eat boiled chicken lol but yeah people do hype up the flavoured, grilled stuff
Jun 19 15:08
@SoumikMukherjee lol sure xD
Jun 19 15:05
@SoumikMukherjee yah xD
Jun 19 15:04
it was good but not as good as people hyped it up
Jun 19 15:03
@Jakobian i had chicken for the first time a few days back
Jun 16 15:34
@Jakobian its 3 intuitive ideas for measurable sets: E is "almost" a finite union of intervals; Every measurable function is "almost" continuous, and every pointwise convergent sequence of measurable functions is "almost" uniformly convergent, and stein develops egorov theorem and lusins theorems as a way of making sense of the 3 vague statements
Jun 16 15:32
@Jakobian anyways its no big deal
Jun 16 09:37
I am thinking that we care more about functions where infinity is attained on a measure 0 set, so perhaps that characterisation helps
Jun 16 09:37
@Jakobian I guess so. I havent gone that far to see a use case of this characterisation though, I am at Egorov's theorem and littlewood's 3 principles
Jun 16 04:35
though they are equivalent
Jun 16 04:34
is there a reaason for the preference to speaking of open subsets of R plus two singletons instead of the order topology?
Jun 16 04:31
makes sense
Jun 16 04:31
@Jakobian oh, i see
Jun 16 04:27
@Jakobian as in, the assertion of $f^{-1}(\pm\infty)$ being measurable vs working with order topology?
Jun 15 15:37
@XanderHenderson ok, so the book is talking about open sets in R still, and for that they are asserting $f^{-1}(\infty)$ and $f^{-1}(-\infty)$ be measurable?
Jun 15 15:30
Stein "and" Shakarchi says the following: "a function $f:\mathbb{R}^d \to \mathbb{R}$ (finite valued) is measurable if and only if it inverse maps open sets to measurable sets", this is fine but in order to generalise the result to extended real valued function $f$, he says extra assertion $f^{-1}(\infty), f^{-1}(-\infty)$ must be measurable, but wouldnt working with the order topology on $R \cup\{-\infty,+\infty\}$ solve the issue,
as in it wouldnt be required to assert $f^{-1}(-\infty), f^{-1}(\infty)$ be measurable?
Jun 15 15:22
@XanderHenderson for some reason I have been calling it Stein Shakarchi, never once pronouncing the "and", but when it comes to Bartle and Sherbert, I always say the "and". Interesting phenomenon
Jun 15 15:15
I like Stein Shakarchi's real analysis so far, atleast the measure part
Jun 14 11:45
couldnt agree more
Jun 14 11:44
it wasnt me, but now i added one more star
Jun 14 11:43
ok nvm, it works
Jun 14 11:38
Stein Shakarchi- Real Analysis states a set $E$ is measurable if and only if it differs from a $G_{\delta}$ set or an $F_{\sigma}$ set by a set of measure 0. what does differ mean? symmetric difference?
Jun 11 05:25
ive decided to accept the TAship for the metric spaces course :P The semester starts in august, so ig i have time to prepare
Jun 9 14:35
5 may not be far from the truth, more like 6 hours lol. also, this TA-ship is only hosting problem solving sessions, curating quizzes and generally clearing students' confusion, no grading on my part. I have a slight hedge I can handle all of this, well see. Not sure if the same professor will take the same course in a different semester, though

with regards to the course, the course is actually on the applied side of thhings, prereqs being real analysis, and probability (and stochastic processes), 10 hours of the module is devoted to revising markov chains, and various processes and brown
Jun 9 11:10
ig 5 hours of sleep per night is not that bad if done in moderation- like, for a semester
Jun 9 11:09
on the one hand I would love to, on the other hand my next semester, in terms of coursework, may be my worst: Measure theory, commutative algebra, Partial differential equation, Intro to Stochastic Calculus, Analysis on Manifolds
Jun 9 11:08
should I take it
Jun 9 11:08
ive been given an opportunity to be teaching assistant for my juniors' "Metric Spaces" course
May 29 09:45
theres this result $\operatorname{dim}(V) \leq \operatorname{dim}(V^*)$, equality iff finite dimensioned. I could show that for countably infinite basis for $V$, we can use a cantor diag argument to say $V^*$ would be uncountable, but if dimension of $V$ is larger than countable, what would one do?
May 11 18:49
is there a book like: set theory every mathematician ought to know, or something like that thats easy on eyes? I open bourbaki set theory and I immediately want to vomit
Apr 13 16:04
@SoumikMukherjee thanks, gonna do it
Apr 13 12:35
Do you guys think it's a good idea to mail a prospective PhD guide and ask him wtf I should be reading/ doing in my life in order to land a PhD under him/her? Though I have 2 more years in my degree, I wanna kind of maximize my chances
2
Apr 4 18:20
@Jakobian I get what you're feeling. Also consolidating knowledge is still important, somewhat
Apr 4 18:14
@XanderHenderson yep, I always carry around a copy of alhfors. I even keep it under my pillow when I sleep
Apr 4 18:13
How have you been doing @Jakobian , btw?
Apr 4 18:12
I guess so. I've been enjoying complex analysis and topology though, on the flip side.
Apr 4 18:10
@Jakobian that's true; and I'm trying to do that rn, but Im parallely doing this "revision" whilst trying to keep up with the class too which has been a bit tough
Apr 4 18:09
@Jakobian yeah, it's a mixture of lang and dummit and foote