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8:00 PM
@Sebastiano on the bottom of that page is the answer you wanted
but you didn't tell me you know the Faraday tensor
 
@0celouvsky yes. i not know Faraday tensor. The three distinct possibilities AND OTHERS points derived from the scalar products
 
@Sebastiano hello there chap
 
@BernardoMeurer regardsssssss and hello
 
What operating system do you run?
 
@BernardoMeurer w7
 
8:04 PM
@Sebastiano Windows?!
Do you like malware?
Proprietary malware
Also spyware tbh
 
@BernardoMeurer what?
 
@Sebastiano You must learn the word of St. IGNUtius of the Church of Emacs
Repeat after me
 
i want to talk about exterior products
 
@Sebastiano He's trying to convert everyone in this chat to free software, just ignore him if you don't feel like talking about that :P
 
"There is no system but GNU and Linux is one of it's kernels"
 
8:05 PM
I do not like viruses and malware
Why this question?
 
@Sebastiano What ACM said is Free as in Freedom, not as in gratis
 
@ACuriousMind hello . . . . .
 
@Sebastiano Well, are you aware that the OS you run is FILLED with malware and spyware from the factory?
 
@BernardoMeurer i use linux xubuntu
 
@ACuriousMind what makes integration over exterior algebras cool
 
8:07 PM
@Sebastiano The system you are referring to as Linux is actually GNU/Linux or as I recently came to call it GNU+Linux
Because there is no system but GNU and Linux is only the kernel
 
@Cows hi
 
@Sebastiano hello
 
@Cows If you mean Berezin integration, I don't think it's cool.
 
@Sebastiano : Good evening.
 
8:08 PM
@ACuriousMind hehe but fermions are awesome though
@Qmechanic hello
 
They're...fermions. I don't feel particular excitement thinking about them
 
@ACuriousMind Is that actually an integration theory in the measure theoretic sense or is it some nonsense?
 
@0celouvsky It's a linear functional on functions on the exterior algebra, I don't care about measures.
 
@ACuriousMind Is it continuous?
 
@ACuriousMind Size doesn't matter? Is that what you're trying to say?
 
8:10 PM
It's probably not a measure since integrating a constant function gives zero
 
@0celouvsky @Qmechanic I asked a question in the chat here on invariants lorentz. if you help me to write it not to be excluded can you help me thanks
 
@Danu I cracked the compactification code via kk theory hehe.
 
That sounds like you just made it up :P
 
@Sebastiano I can only help you when you free yourself from the shackles of proprietary malware
 
hehe i really did
lol
 
8:11 PM
@Sebastiano : Can you link to your chat message?
 
Hey @ACuriousMind did you ever get into some detailed stuff regarding octo***nions?
 
@Cows Why is everything funny to you?
Just wondering
 
@Sebastiano Multiple people have told you that they don't really understand what you're asking but you keep repeating the same question.
@Danu Not really, no
 
@0celouvsky I dunno, I am usually quite happy when I log on here, lol
 
@ACuriousMind what should I do?
 
8:13 PM
I'm currently wrestling with an unsettling amount of algebraic geometry, though :P
 
@ACuriousMind What kind?
 
@Qmechanic i not undestand
 
@0celouvsky Also I just discovered how lolz work on the interwebs and am excited to use it hehe
 
@dmckee 1-800-VHDL-HELP
 
@Danu The complex kind, in particular (weak) Fano 3-folds
 
8:14 PM
Oh, I could maybe help... Probably not though.
What are you looking at?
 
verilog hardware dev lang
back in the day peeps
 
Also what it weakly Fano? $c_1$ non-negative?
 
(I guess you can define Fano manifolds over arbitrary fields but I'm just interested in the complex kind)
 
desc lang
 
@Danu Yes, plus $c_1^3$ positive
 
8:15 PM
Okay. Why that?
 
At least I think so because those damn algebraic geometers phrase everything in terms of divisors instead :D
 
strange slash
 
I know something about divisors... Maybe I can translate?
 
@ACuriousMind do you upright the c in your notes?
 
@Danu I am translating fine, it's just taking me a while
I'm looking at these things because they give the building blocks for the twisted connected sum construction for $G_2$-manifolds.
 
8:16 PM
Someday I will be king of QFT hahahaha
 
Oh, I'd love to hear about that.
You saw the recent $G_2$ instanton papers?
I wonder what it means :D
 
@Qmechanic quora.com/Why-is-this-invariant-in-Relativity-E-2-c-2B-2 . my teacher He has made similar considerations starting from the inner products and the invariants lorentz
 
@Danu Mhhh, if they're about $G_2$ as a gauge group then I skipped them because that's not what interests me currently
 
Have you guys heard of the new laptop ban during flights?
 
@Cows no - why would they do that?
 
8:19 PM
But isn't that super related to the twisted sum construction? Are you reading the paper by Klemm et al?
 
however, I have to go and greet everyone with a lot of warmth--------- hi to everybody
 
@Danu I could just take this construction as a black box but I probably want to hunt for some specific examples soon so I should understand how they are constructed
@Danu yes
 
@heather something about explosives that outsmart our detectors
 
I meant this paper, besides the Klemm one arxiv.org/pdf/1703.06329.pdf
 
@Cows, it's sad that they need to do that
 
8:19 PM
@heather CNN is all over it
 
Klemm does some awesome stuff, huh...
 
@heather that's true, but I guess it could be a business opportunity for a workaround say may be laptop rentals, or laptop shipping, or data transfer services? Have been thinking on how to capitalize on it
 
@Danu The cowards take a sort-of semiclassical limit though instead of getting quantum! ;)
 
lel
 
@Sebastiano : Ah. OK, you asked more or less the same here. That is probably too broad for chat.
 
8:22 PM
@Cows, hmm, interesting.
 
@ACuriousMind Quantum is when it starts becoming nonsense :D
 
You gotta love the Kovalevton for its name alone, though
 
Mike knows about the twisted sum construction, by the way.
But from a math POV obviously
 
@Qmechanic are you one person, or a lot of people. You are quite active on this site.
 
I'm sure he'd love to explain
 
8:22 PM
@Danu I have enough literature, I just need to absorb it.
 
@Cows He's a robot
 
And it's not that I'm currently having a particular road block, it's a just a lot to wade through if one wants to understand it in useful detail
 
@0celouvsky wow. I always knew there was something super human about Qmechanic.
 
@Cows : Ha.
 
There's also a funny observation that all TCS-constructed manifolds have a particular value of a certain invariant of $G_2$-manifolds, I wonder if one can detect that physically
 
8:25 PM
hehe
 
Hmm.
Also, how do weakly Fano manifolds show up here?
 
what is this Fano manifold thing you go on about?
 
@Danu You do TCS starting from two asymptotic CY cylinders, and you can apparently get those cylinders by blowing up the Fanos
 
scratch that too abstract to read now
 
I'm currently (well, not right now, but that's what I'd do if I were working on it) trying to understand the exact description of that blowup
 
8:26 PM
How is $c_1$ affected by blowup?
 
There's also a nice fact that the weak Fanos sit over ADE-singular weak Fanos, so one gets the ADE singularities for gauge group enhancement somewhat "for free"
@Danu I'll answer that after I've reactivated my knowledge of what a blowup exactly does ;)
 
I guess that in dimension four, $c_1$ becomes more negative
 
Didn't use all this geometry for more than a year, it's a bit rusty
 
@ACuriousMind You can think of it as the connected sum with $\overline{\Bbb P^n}$
 
2 was right, we're blowing up K3s
I think
 
8:30 PM
So at least in dimension four I think what you can do is look at submanifolds representing Poincare dual homology classes corresponding to $c_1$; I would think that then the $c_1$ of the blowup is represented by a connected sum with some copies of a $\Bbb P^1$ inside $\overline{\Bbb P^2}$
 
Sounds about right.
 
That'd make $c_1$ more negative, right @Balarka? Or am I confusing something?
 
You say $c_1$ and take homology dual, I say "anticanonical divisor" and take cohomology dual ;P
 
lol
Anticanonical divisor is just (a fancy word for) the zero locus of a generic section of $-K_X$ right?
 
It's $-K_X$ itself
or, well
 
8:32 PM
$-K_X$ denotes a vector bundle for me
 
I think you are correct. If you pull $c_1$ of the base along the projection map of the blowup and take it's dual it should be sum of dual of $c_1$ of the blowup with a multiple of the exceptional divisor.
So, yes, $c_1$ of blowup should be more negative.
 
Cool
 
@Danu yeah, the geometers aren't very careful with their terminology there - they often use $-K_X$ both for the line bundle and the corresponding divisor
 
I'm trying to start the Besse tome on Einstein manifolds and it's killing me :P
@ACuriousMind I think it's actually a very good abuse of notation: Very suggestive (and can't really lead to meaningful misunderstandings)
 
@Danu I am very sure I won't know what it is, but for the sake of exposure to me, Could you tell me what you guys are going on about especially with the Fano thing, and why it is important? I will then do some googling for intellectual sight seeing
 
8:34 PM
I think the heuristic "a line bundle is its $c_1$" isn't so bad :)
 
@Danu It can confuse the hell out of the unwary reader though because $K_X$ switches between being something inside the manifold you can intersect with and something "over" the manifold
 
The Besse book doesn't prove even half of the statements :\ Most appear without reference, too...
@ACuriousMind I guess I'm biased because I've been using this for a while :P
 
@Danu It's a trivial exercise for the reader
 
:'(
 
0
Q: VHDL Entity port does not match type of component port

Bernardo MeurerI'm working on a MIPS-like CPU in VHDL with Xilinx Vivado. I have a component for my BranchControl module, which goes like this: library IEEE; use IEEE.STD_LOGIC_1164.ALL; use IEEE.STD_LOGIC_UNSIGNED.ALL; entity BranchControl is Port ( PL : in STD_LOGIC; BC : in STD_LOGIC_VECTOR(...

 
8:35 PM
Weren't you reading the book by Wolf at some point?
 
1 upvote = 1 prayer
 
Does he talk about symmetric spaces and/or 3-symmetric spaces?
 
For my soul having to deal with this BS project
 
@Danu I got through the first two chapters and then he hit me with the damn group theory
 
@Danu The $G_2$-invariant I mentioned relies crucially on a paper by Milnor that asserts that the spin bordism group in 7 dimensions is trivial. Milnor "proves" this by saying "Take the relevant Thom complex and do a formidable computation. No further details will be given."
 
8:36 PM
Or Einstein metrics/(almost) complex structures on homogeneous spaces?
@ACuriousMind ROFL. What an ass!
 
@Danu You want Helgason for that.
 
Well, if it's Milnor
 
That's just an insult :P
@0celouvsky I need things that were not known back in those days :(
I need like 80's or later
 
Wolf is older than Helgason
 
It is?!
 
8:37 PM
It's in its 6th edition, which is why the date on the book is 2010
@Danu Maybe not older. But it was around in the 60s for sure.
 
Oh well, then that might be why my supervisor didn't mention it :P
He said several times that Helgason is too old
 
Oh, 1977
 
geometry is too hard
 
Ah, so basically the same time as Helgason
@BalarkaSen :'(
 
No, Helgason is 60s I think
 
8:39 PM
I just want to quote the classification theorems without comment :D
@0celouvsky Oh, my edition is 1978; probably not the first.
 
Shit, I dunno. I might be mixing that up with Kobayashi-Nomizu
Those are definitely 60s :D
 
60s were a golden fucking age man
 
@BalarkaSen I need halp with a series ;_;
I can't into limits
 
Being a topologist or geometer between 1950 and 1975 must've been glorious.
 
well i'm not gonna do it
 
8:40 PM
I guess the gauge theory stuff is also awesome though.
 
Or analyst
 
@Danu Yeah, I went there looking for some insight why every spin 7-manifold can be filled with a spin 8-manifold and that was all I got.
 
Bourbaki did wonders for analysis
 
@0celouvsky That's never glorious :P
 
:(
@Danu Yeah Helgason 1978
I have a 2001 reprint
 
8:42 PM
@Danu drugs
cool stuff
 
@Danu . . .
 
That, too.
 
@BalarkaSen GET GET GET GET GOT GOT GOT GOT
 
@Danu Most of the results in the intro to Besse are standard Riemannian geometry...then there are some that are out of nowhere and with no reference. Feels bad.
 
blood rush to my head lit hot lock
 
8:43 PM
@BernardoMeurer Disjointed Houdini baby
 
And you claim to have listened to their most recent album?
 
Ah
I don't own Bottomless Pit :(
 
ah k
 
I only have Exmilitary and The Money Store
Exmilitary is still my favourite
lit af
 
8:45 PM
Ok I am going to learn about Fano manifolds and come back here in a week
 
@0celouvsky Did you hear the track Kendrick dropped? Fucking fire
 
I did not
I am currently trying to understand an inequality
 
@0celouvsky Yeah... And teh things I need are in chapters like 7,9,14. Feels real bad.
 
@BernardoMeurer epic beat
 
8:47 PM
@Cows It's an awesome track
Kendrick is a beast
 
What's the large $n$ behavior of $$\frac{(r+\epsilon/2)^n}{(r+\epsilon)^{n+1}}$$
that's a bad question
it would be like $1/r$ but that series diverges...
 
It definitely would be like $1/r$
 
yep $1/r$
 
that $\epsilon/2$ is a mystery
how did you get that Mr. Yosida...
 
there is just too much knowledge in the world
 
8:51 PM
that's true
 
there's too much everything in the world
 
@BalarkaSen I disagree :P
 
Ahh...comparison with the geometric series, of course
the geometric series might be one the greatest things in mathematics
 
@ACuriousMind "All parts of the house are repeated many times, any place is another place. There is no one pool, courtyard, drinking trough, manger; the mangers, drinking troughs, courtyards pools are fourteen (infinite) in number. The house is the same size as the world; or rather it is the world. However, by dint of exhausting the courtyards with pools and dusty gray stone galleries I have reached the street and seen the temple of the Axes and the sea. I did not understand this until a night vision revealed to me that the seas and temples are also fourteen (infinite) in number.
 
9:03 PM
Pass me some of these drugs, dude :P
 
VHDL? No one?
 
"expansion in positive and nonpositive powers"
 
@ACuriousMind Keep awake for 48 hours, read Kafka and listen to Scary Monsters and you're guaranteed to be on high
 
Why not just say "powers"??
@BalarkaSen the Skrillex record?
 
Skrillex? Huh? I'm talkin' about David Bowie, like I always do
 
9:05 PM
o
 
there's levels to it
 
(the passage above is from a short story by Borges, by the way)
 
@BalarkaSen Suppose I'm doing a Laurent expansion at infinity and I only have $1/\lambda$ terms. How do I show that there's a smallest $|\lambda|$ for which the series converges?
 
hell if i know man
 
I thought you liked complex analysis!
 
9:13 PM
Is there a smallest $|\lambda|$? I mean look at $1/(1-1/z)$ and expand near infinity. That's $1 + 1/z + 1/z^2 + \cdots$. Change charts so it becomes $1 + z + z^2 + \cdots$ near the origin. The region of convergence is $|z| < 1$.
That's open.
 
@BalarkaSen I want the series to have only negative powers of $z$, but I don't know if that's essential to this example.
Oh, wait
 
Laurent series of $1/(1-1/z)$ near infinity has negative power terms da?
 
I want the smallest number $r$ such that the series converges for $|\lambda|>r$
I know it converges on an annulus already
 
That's believable.
 
So the inf of the set of such $r$ exists
Not much to prove here
 
9:16 PM
Ya
Alright, I'm gonna head to bed
 
@BalarkaSen So if I have a Laurent series, am I guaranteed to have convergence on circles?
no wait!
Ah, the convergence is absolute
complex analysis is the worst
 
0
Q: How do I upload a pdf file?

WRICHIK BASUI want to upload a pdf file while answering a question, but could find no such option on both the desktop and mobile version. Is this present and I'm missing it, or absent?

 
how do I sleep?!
I am on 3x dose of sleeping pills
my brain is too stubborn
it doesn't want to sleep
and I have 6 hours for my exam
 
@YashasSamaga Close your eyes and think of Free Software
Free as in Freedom
 
9:30 PM
.
this has happened before
but ...
 
@YashasSamaga What exam?
 
Oh man
Ok
Try and relax
If I can't sleep I go for a walk
 
Last night I was angry and nervous so I went out for a stroll for about an hour or two, came back home and fell straight asleep
Yep
It helps me at least
 
9:32 PM
I'm guessing the fano variety and manifold thing is connected to string theory too?
@Danu @ACuriousMind @0celouvsky @BalarkaSen I'm guessing the fano variety and manifold thing is connected to string theory too?
 
@Cows Don't mass ping like that
People are going to stab you
 
@Bernardo hehe ok I won't do it again
I am really curious at why they were quite excited about it
I mean I could just read it, but I lack motivation
 
God, power series are magic
 
@0celouvsky tell me about the Fano manifold secret
 
I don't know/care about it
 
9:41 PM
@0celouvsky oh,
I feel like I know nothing again
I was really excited that i might be leveling up , but after i heard about it and did some googling, it is official. I am not informed about anything
I hope to be able to go to school soon
When I do I will try to take all the math courses, I heard about here
and will learn in some pedagogical order
 
There are plenty of mathematicians who don't know or care about algebraic geometry
 
I bet they hide when they hear the peculiar footsteps of algebraic topologist hehe
 
Meh it's always helpful to know a little algebraic topology
 
yeah
I think Danu was like I can't even relate to cows, and life is to short for lengthy explanations lol
 
10:31 PM
What's going on in here?
 
@JohnRennie I fixed the movement!!
It was just a silly fault in me not resetting idx and doing memset on the buffer after each loop
Also, my implementation of the graphics struct made the game faster!
Maybe it's me being crazy though
THIS IS AWESOME
I LOVE C
 
10:49 PM
@BernardoMeurer What did you build?
 
@alarge Hey man, long time no see, how are you?
School project, the 2048 game in C (99) and SDL2
 
I'm good. Why C+SDL2? Any particular reason?
(as opposed to say C++/SFML)
Just curious is all
 
@alarge C because the course is about pure C, not sure why they still use C for CS101
But sure
C++/SFML would have been far, FAR better
Try making a textbox on SDL :P
in C
@alarge I can give you access to the code if you want to go snoop, it's a private GH repo
 

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