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3:00 AM
I suspect that's because us rookies are drawn to maths given that it promises complete precision, and then you see that you have to go down, down, down... to actually realize that promise. I am content for now going no further than Enderton though
 
it's not the end of the world to power through anything, and i don't want to make it out like it's scary or inaccessible, i just wonder whether everyone bothers to examine why they want to do set theory
 
books are not meant to be read from start to finish
that's my general advice
 
it's like if you were learning a language, at some point in acquiring the rules of grammar, and their big exceptions, and the histories of how words or figures of speech developed from other words or languages, eventually you reach a point where you're learning stuff that > 99.9% of native speakers have never heard of and never use
and with something like set theory, you hit that point sooner than a lot of people think
and yeah i actually wonder how many books are actually worth reading start to finish
a lot of standard textbook advice fits the format "read through chapter x and then stop," where x is often only a little more than halfway through
 
the only book I ever read from start to finish was Halmos
and that was all the set theory I ever needed, too
did it during a spring break once, it's the mathematicians paying your dues to read set theory at some point, I guess
 
But surely something to be said for just enjoying a good book :) I agree some are slogs, but some are just really pleasant. (Baby) Rudin fell in the first category (at least for me), but Enderton I am really enjoying. LADR was another beautiful one
LADR was long ago and I'm so out of practice that i gotta do another LA book sadly, hence hoffman and kunze
 
3:19 AM
@leslietownes Baby Rudin: stop after chapter 7.
 
@EE18 Try LADW
 
3:35 AM
have heard great things about that one Soumik
Incidentally, has anyone read the books intro to Statistical Learning or elements of statistical learning?
I know for mathematicians these things are probably looked at as applied statistics/stuff we've known about forever
but figured i'd ask
 
@Thorgott I think so. I can't help it. I do it anyways. I start from preface and all the way to the end.
 
 
3 hours later…
6:46 AM
even with baby rudin? i don't believe it.
i believe that some people might have hit chapter 8, because i did, despite xander's advice (which is the best advice and the advice taken by my first analysis prof). but nobody has ever gone through chapters 9, 10, and 11 of rudin. you can't. your brain shuts off.
 
7:01 AM
if you finish chapter 11 of rudin you wake up and someone congratulates you for exiting the simulation
 
7:38 AM
🤣
 
8:01 AM
I was evaluating this limit and got answer as 1. but the answer key claims to be 3/2
What is wrong in my method ?
Can anyone please correct me ?
 
8:42 AM
@KavinIshwaran everything
Your method "proves" that every limit is equal to 0 as well
$\lim_{x\to a} f(x) = \lim_{x\to a} \frac{f(x)}{x-a}\cdot (x-a) = \lim_{x\to a}(\frac{f(x)}{x-a}\cdot 0) = \lim_{x\to a} 0 = 0$
@leslietownes because I'd like to get insight into independence proofs and methods such as forcing
 
@leslietownes not with Rudin :)
 
9:03 AM
@Jakobian Ah. I get it. I have seen some questions where they apply limits individually. But didn't know where it is applicable and where it isn't.
 
@KavinIshwaran I don't know what that means
 
@Jakobian suppose if there is a sinx term in an expression and the x tends to zero, they multiply and divide by x and take that particular term to be 1
 
@KavinIshwaran you can't do that unless it makes sense with respect to the rules that limits obey e.g. products, sums, quotients of limits
You would have to be more specific and only then we can discuss if in a given limit it makes sense to make such substitution. In general the answer is no, it doesn't make sense
 
9:18 AM
to be more specific, in a question which goes like this :
limit x tends to zero (tanx - xsinx)/x they multiplied sin x by x and divided it with x (that particular term alone and then LH rule is used)
@Jakobian Oh Ok. I will make a memory note on this.
@Jakobian Thank you for the clarifications :-)
 
The above is supposed to be an example of a sequence that converges in mean but not pointwise a.e. I simply do not understand it, since I believe there are some typos. How can n increase from $2^m$ to $2^m-1$? Also, is $f_4$ correct? Mightily confused.
Trying to figure out what the correct example should be...
 
@KavinIshwaran sounds like wrong reasoning
 
@Jakobian Oh Ok, I will restrict myself from using that
 
9:34 AM
@psie typewriter sequence
f_4 is incorrect as well
26
Q: The Typewriter Sequence

FabianThe typewriter sequence is an example of a sequence which converges to zero in measure but does not converge to zero a.e. Could someone explain why it does not converge to zero a.e.? $f_n(x) = \mathbb 1_{\left[\frac{n-2^k}{2^k}, \frac{n-2^k+1}{2^k}\right]} \text{, where } 2^k \leqslant n < 2^{k+...

 
ok, then $f_4$ should probably be $1$ on $0\leq x\leq 1/4$ instead
and $0$ elsewhere
 
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