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00:00 - 12:0012:00 - 23:00

12:01 PM
@BalarkaSen which book?
 
I started with short story collection Night Shift; less commitment than starting off with novels
 
how long till your fight leaves?
 
I'll get into novels if I like these
 
have you seen any of his movies?
 
What do you mean by his movies
He's an author
 
12:04 PM
based on his books
 
I think I only read The Green Mile (which was good) by Stephen King but I'm not sure
 
I've only seen The Shining and The Dead Zone
@Alessandro Ah ok
 
Is the two open set gluing definition of sheaves in G-H correct ? I think you'll have some sheaves in this definition which are actually preshaves (eg, "sheaf" of bounded continuous functions)
 
what is the defn
 
in GH ?
 
yes
 
If I'm not mistaken, this implies the presheaf of continious bounded functions is also a sheaf, no ?
 
12:21 PM
Does $\Bbb A^2$ mean $\Bbb A^2_{\Bbb C}$ conventionally ?
 
@Lelouch Right, they should not say a finite cover
you should be able to glue over as many open sets as you want
 
yeah, cool thanks
the section on sheaves is a bit weird here
 
GH is riddled with typos from what I have heard
I have not read it
 
@BalarkaSen yeah that's a huge problem. also they handwave A LOT in the section on poincare duality and intersections, which is really hard to properly understand
 
lol nice
 
12:24 PM
@BalarkaSen did you read Huybrechts ?
 
I don't know any complex geometry beyond hearsay haha
I haven't read any texts. Only a little bit of Forster
 
@BalarkaSen ohh, the book on Riemann surfaces ?
 
yeah
 
I should have read that instead of Donaldson. Donaldson does very little sheaf cohomology
are you attending MM's lectures now btw
 
I wanted to read Donaldson! seemed cool
yeah I am
 
12:26 PM
how many people are there now ?
those on the discord and goutam ?
 
yeah pretty much
gaurav you mean
 
yeah sorry
I heard a guy from IISER came and sped up insanely fast ?
 
No he basically gave two 3 hour talks on his recent work on Cannon-Thurston maps. I couldn't follow much
 
lol, sad. And your classes at ISI started ?
 
12:29 PM
what are they doing for midsems ?
 
waived
 
endsems waived as well ?
 
not yet lol we'll see
they say we'll "definitely" have endsems
 
yeah that's waht people here think as well
 
im not too confident. maybe as a take home
 
12:30 PM
but idt those will open before Feb
people are optimistic about conducting endsems physically at Jan
 
lool that wont happen i think
i think my university is still in quarantine zone
 
oh, there's still quarantine in places now ? lol
 
bangalore is blowing up dude
4
 
47 mins ago, by Make Stackexchange Great Again
rip
 
@BalarkaSen Stephen king couldn't write horror if held at gunpoint
He's good at writing characters though
 
12:35 PM
oh thats bad news
 
and his movies are ok
 
lol
judging authors by movie adaptations
> judging covers by books
 
when you've seen one cover you've seen them all (by self-similarity of fractals)
 
they must have a say in the writing of the script
 
not always
 
12:40 PM
then they've sold their copyright
 
@MakeStackexchangeGreatAgain if that was true then hollywood wouldnt have existed
 
Yeah, we'd have Bollywood
 
lmao
 
Buying a copyright doesn't make you author
That reminds me of the fact that elon musk bought the title of co-founder of tesla
 
LOL
 
12:43 PM
Which imo makes absolutely no sense
It's such an american thing to do
 
since when did anything elon does make sense
 
He's rich, so he must be right
 
selling flamethrowers
sending cars in outer space
 
Capitalism at its finest
 
The latest news is him turning SpaceX into a weapons delivery system for america
 
12:45 PM
LOL
 
No, it's for the beauty of science and the democratisation of space traSIKE I'M HELPING AMERICA WAGE WAR
 
Is there a simple explanation for the difference between "axiomatic" and "constructive" definitions of objects?
I get what axiomatic means, but am struggling to find resources online that compare the two
 
@Astyx Lmao
 
Elon, the lover of plublicity stunts
 
12:46 PM
yeah
 
rich heir to emerald fortune earned in apartheid south africa
 
Different flavors of publicity, but yeah
 
not the sharpest lightbulb in town
surprised?
 
 
2 hours later…
2:40 PM
3
Q: The axiomatic method to real number system VS the constructive method(genetic method)

iMathAccording to book Georg Cantor: His Mathematics and Philosophy of the Infinite - Joseph Warren Dauben , David Hilbert claimed that the axiomatic method to real number system is more secure than the constructive method(genetic method) . The axiomatic method described as These axioms include...

 
thank you @skullpatrol
 
np, pal
 
Hello! I don't think this is worth an actual question so... Given this set of data points {{2,0},{12,0},{3,1},{11,1}, {4,2},{10,2}, {5,3},{9,3}, {6,4},{8,4}, {7,5}}, Wolframalpha gives a really nasty linear interpolation... But I'm sure there's a really nice one using the absolute value operator (need this for programming purposes). It just have to fit these data points. Thanks!
Wolframalpha gives a really nasty polynomial* interpolation...
 
y = 5-|x-7|
 
2:58 PM
That's perfect, thank you @LeakyNun. Out of curiosity, is there a method to find this or just by observation and trial and error?
 
pure skill :P
 
3:18 PM
okay, so if $f_n \in L(X)$ and $\sum_{n=1}^{\infty}\int |f_n| d\mu<\infty$, how do I show that $\sum_{n=1}^{\infty}f_n$ converges almost everywhere?
 
3:39 PM
3
Q: How to determine if Q-learning has converged in practice?

WANGWANGZII am using Q-learning and SARSA to solve a problem. The agent learns to go from the start to the goal without falling in the holes. At each state, I can choose the action corresponding to the maximum Q value at the state (the greedy action that the agent would take). And all the actions connect s...

:D
 
Hi folks. Can anyone offer some advice for simplifying $\cosh\left(\sinh^{-1}(x)\right)$ (which answer is $\sqrt{x^2+1}$).
 
Take the derivative ?
 
@Astyx Well, this is the result (the denom) of calculating the deriv of inverse sinh(x).
 
You can derive it again
And things simplify nicely
 
I don't understand. I have $d/dx \left(\sinh^-1\right) = ... = 1/ \cosh\left(\sinh^{-1}(x)\right)$. Why would I take the derivative (of the derivative).
 
3:53 PM
My bad
You can use $\cosh^2-\sinh^2 =1$
And notice $\cosh >0$
Actually my first method works as well
If $f=\cosh\circ\sinh^{-1}$
You get f' = x/f
Which is an ode with solution $f(x)=\sqrt{1+x^2}$
(arguably this is more sophisticated than using the square identity)
 
 
1 hour later…
5:04 PM
Prove that the class of functions f(x) = o(x+1) satisfies or does not satisfy lim 1 / f(x) as x -> 0, where f(x) is a function of x and o(x+1) is little-oh bound. If the satisfaction does not hold for this particular example, what would a general method to prove such satisfaction relations?
What would be the way to go about finding such proofs
 
 
1 hour later…
6:16 PM
@Astyx Hi. I was in class. Getting back to this now
@Astyx How do you use the identity on inverse sinh?
 
 
1 hour later…
7:26 PM
if $x_n \leq y_n$ for all n and $x_n->x$ then does there exist $N$ such that $x\leq y_N$?
 
what if $x_n=y_n$ and the sequence is strictly increasing
 
7:55 PM
@Jeff This is true at all points, in particular this is true at $\sinh^{-1}(x)$
 
@Astyx tu veux jouer?
 
8:12 PM
0
Q: Problems with gradient-biased actor critic methods

user76284To my knowledge, there are at least 6 different variants of Actor Critic: \begin{array}{l l l l} \text{actor gradient} & \text{critic gradient} & \text{actor gradient biased} & \text{name} \\ \hline \sum_t \nabla_\theta \log \pi_\theta(a_t | s_t) \cdot (R_t - V_\theta) & \nabla_\theta \frac{1}{T}...

In case anyone's familiar with this area.
 
8:57 PM
@TedShifrin hi
 
Hi Leaky
 
Hi, @Leaky @JoeShmo
 
Hi Ted
 
@TedShifrin what do you look for in a personal statement for phd?
 
I haven't read that many, actually. But my general advice is to be as non-generic as possible. Talk about specific things that have engaged and challenged you, not just about how much you "love mathematics."
 
9:36 PM
@TedShifrin from a young age I have been enchanted with the beauty of maths etc etc etc
 
Right. Blah.
 
9:47 PM
If $p < 1$, how do I show that $\frac{1}{k} \le \frac{1}{k^p}$? Induction? Calculus? I don't see the best way to prove this statement.
 
Is $k$ a natural number there?
 
Yes.
 
Rewrite without fractions and simplify the algebra.
 
So $k^p \le k$?
or $k^{p-1} \le 1$?
 
Or $k^{1-p}\ge 1$ might be easier.
 
10:18 PM
And then use induction?
 
what induction do you have in mind
 
Regular induction I suppose. $k = 1$ case is trivial.
 
but how are you gonna induct
 
No idea...maybe use Bernoulli's inequality...
 
too copmlicated
 
10:26 PM
Yeah, I agree.
Do I use calculus?
 
tell me your definition of exponentiation
 
I don't have any particular definition, so you can choose whichever.
This problem is just a subproblem in my complex analysis homework....just trying to remember how to do basic shit.
 
how bout $k^{1-p}=e^{\log(k)(1-p)}$
 
Okay. That sounds good.
 
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