#serious-discussion
1 messages · Page 503 of 1
I think you are conflating different usages of the word closed
When you say "closed" you have to say what is closed (i.e. operation)
Yes, vector addition, multiplication, and scalar multiplication are closed but that's not the same as closed algebraically.
both of them, vector addition and scalar multiplication
aaaah
Yes, vector spaces are closed under these properties
how come
Definition
For an operation + to be closed it means ∀a,b∈S, a+b∈S.
In fact, I would argue that if you define these things properly the word closed is simply redundant
no i mean how come they're not algebraically closed
why would you write this symbolically lol
the closure under the operations does not guarantee algebraic closure
derp
most fields are not algebraically closed
i see ok thanks
bruh
in class rn my prof is trying to parse a homework problem that he literally wrote for this week
someone asked him "wait how do I do this" and now he's rereading the problem to remind himself how it works
Of course they are not alg closed
You can define a vs such that the element satisfying root not be there
Sorry if the conv Changed

is that weird ?
my professor once forgot a certain solution to a problem and we went on to prove it together in the next ~25 mins lol
it was very productive and idk if he did it on purpose
james new pfp 
oh ye im just messing with my friend who dislikes anime for a bit lol
ile go to old one later



Sometimes profs pretend to know less than they do but most of the time they just haven’t thought abt it in awhile
ye that's fair enough , you can't keep up with every single problem all the time.
hey, I was in help room 12 and it just disappeared, can't find it among occupied, available or hidden, what do I do?
thank you very much
why is the discord server picture a coffee mug 
Cuz' donuts, y'know.
coffis
It's not a coffee mug, it's a n-dimensional hypermanifoldian Laplace pi-surface solenoid.
da frik

does anyone have a link to the stackexchange thread that was pinned to one of the analysis channels long ago
i remember it was a really difficult problem on polynomials and compactness(?) where some dude said it was a problem from a first year course in calculus
even though it very clearly wasnt
I think the solution involved Baire's theorem or smth
and the guy had misread the quantifiers and it became trivial if they were like, the other way around
Sorry to intrude but my brain is a bit off today. Do you guys what is meant by evaluating this integral? The context is a grad real analysis course and no helpers seem to be available.
$lim_{n \to +\infty} \int_{0}^{\infty} [(nsin(x/n)/((x^2+1)x))]$
chernberries
I guess you're supposed to calculate that limit
I’m in help room 22 if you want to see my attempt
using e.g. dominated convergence thm
Yeah I’m not sure of a canonical way to find the right function that bounds f_n
I’m pretty sure I got it; just let F(n) = that integral, take the derivative then use DCT
Have to use MVT somewhere I think
i need people to study with. but all my friends dont care abt their grade cuz its senior hs. is there anything i can do
hire a tutor 
are you a graded module
Because better acceptance rate?
Yeah??
If you choose a big major with limited classes then theyll always pick the guus with 95% average over someone with 70% average
In uni?
College?
??
For better acceptence rate in the later schools?
I just said it
if you're bold
go to a local library when you study
and sooner or later if you see someone who you think would be fun to sit next to
walk up to them and ask politely if you can sit next to them
and just study
and once they leave be like "hey id like to get to know you" or something
be like "im looking for a study friend" or something
lol imagine caring about your next school before you finish the current one
guys simple doubt :
{0,1}^4
is it true that above notation means lot of sets with 4 elements in it ?
like :
{1,0,1,0},{1,0,0,0},{1,1,1,0},{1,0,1,1} etc
Yes
thanks bro
you want us to design your experiment for you ?lol
make better friends
bru ur on discord
use DISCORD!
literally so many study grps
A = {ω ∈ Ω|(ω1, ω2, ..., ωn) ∈ A(n)}.
i am confused on what this set looks like
anyone please help
not sets
tuples
you could also describe it as the set of all functions from {0,1,2,3} (the set notation for 4) to {0,1}
could you put it into latex
A = (ω1, ω2, ..., ωn) like this ?
that was in response to your previous question
i cant, i am not familiar with latex
people will be able to help you much more easily if you learn it
it's not very difficult
so this one wrong ?
In case you have heard before of the Steiner symmetrization, I made a simulation that lets you play around with it https://jsfiddle.net/25zbc8ao/
Test your JavaScript, CSS, HTML or CoffeeScript online with JSFiddle code editor.

hm
is there an n- dimensional calculus
like calculus i-ii covers 2 dimensional mostly
calc 3 covers mostly 3 dimensional right? or is this where n- dimensional is covered
lol what 
calc 3 covers multivariate
and yes there is n dimensional calc
probably even infinite dimension
idk
how do you only learn 2d but not generalise that lol
how do american calc courses work
nope
Upto Calc 2 then?
is it like only for R2->R2
why would you do that lol
kinda
Differential Geometry is pretty much the "n-dimensional" version of calc 3.
in one of my classes we just started using all the calc 3 theorems in R^n instead of R^2 and R^3
and it was just like
ok, i guess all that shit was the same in any dimension? but no one ever mentioned it
Curl operatorS in n-dimensional setting 
😌
i want a cool partially ordered field that isnt R or C with usual orders
?
thatd imply 1<=0
i asked for a ordered field not for a field with a order in its underlying set
kid are you kidding
superreal numbers
what does it mean if something is closed
its not open
whats the difference
tbh thats not even true
its when its complement is open iirc
idk havent taken topology yet
what context
Oh the above image
well in general ig
it means many unrelated things
But in this context I also have never seen this usage of closed
@bronze pelican
Do you know?
My guess is that the closed here refers to "closed under the first order properties of the reals"
but thats not very good
I read this
Sounds right
but this does not explain the usage of the word closed
well what does that mean
in particular the only other usage of closed on that page
is to say that the real closed fields are not algebraicly closed lol
It means that very simple statements about the real numbers are also true in these other fields
True 
I think model theorists just wanted the abbreviation RCF to rhyme with ACF which stands for algebraically closed fields
cursed
this is why i do analysis
are all global extrema which arent at endpoints of a continuous function definition also local extrema?
why the endpoint condition
cant have local extrema at endpoints can you
why not?
arent they defined on open interval subsets of the domain
yes
but e.g. [0, 1/2) is open in [0, 1]
anyways, i think if you use sane definitions global extrema are also local extrema
ok youre right idk why i thought that then lol
anyway ty

I actually understood lecture today 
$(\exists l\in{lecture})(l\in{things understood})$
Shuri2060
Shuri2060
👀 👀 👀
What is the criteria to be a helper?
imagine wanting to be an helper
Wow just directly pinging mnoop
Bahahah that’s what I was thinking too
how could we use Bayes' Theorem to analyze situations when the sample space is partitioned more than once?
phrasing this question to make it look right took a lot of time btw

Inside of #help-1
Is there any standard variable when working with quaternions
Like x for reals or z for complex
I've seen q used
Makes sense
What facts should I add to the site?
My goal is to make every number have interesting facts about it.
if u do that...then maybe the facts would no longer remain intteresting
How many numbers are you adding in any case
Like are you stopping at 500? 1000?
Wikipedia has some properties of the lower numbers which could be useful as a starting point
Although later on it peters out (see 502 = 2 x 251)
I think that's the best I can do. anyways, it was just a curiosity. maybe as I learn more and more of it, I will get the answer by myself.
thanks Todd
https://www.probabilitycourse.com/chapter1/1_4_2_total_probability.php @midnight iron is this what ur looking for
Calculate probabilities based on conditional events
what are kinds of functions that f that after dividing by x i can find inverse function explicitly
i mean inverse(f(x)/x ) exists in symbolic form
?
(ping if answered)
thank you mirza!
I enjoyed answering the homework question so much. Is there any platform where you got paid for tutoring?
Learning is doing though
but u gotta do stuff to leanr as wlell

also wait, is that u in ur dp?
u look cute 
learn how to automate as much as possible
so you can do less and learn more
Yes it is me, thank you 🥺🥺
ahah don’t I wish
It automatically generates facts
ah auto-generated
But some parts of it are customized for specific numbers
Like divisibility tests for specific numbers are customized
I'm assuming stuff like factors or whatever can be automated without too much trouble
that part's pretty cool
@charred mortar I'm trying to find more facts about numbers to add to it though
Like more tests I can apply to see if the number has any other interesting properties
I still think you could search wikipedia's list of properties for low numbers, like say 6 or 12, to get some ideas
and probably have those properties apply to most of the integers in some fashion
I actually have been doing that
Ah well I guess a number theorist would be able to provide better answers
One of the things I want is more tricks
I’m not one unfortunately
Like the sum of three palindromes one
Is it JS driven?
If the facts are generated I hope they are done once then stored in database, then perhaps verified once and then called as wanted
You might want to RNG at either the server side or client side to vary facts shown
Could be more interesting to not mention 1729 as a taxicab number to some visitors
Yes
I could cache them in a database
but if you mean manually verified that would be very tricky
since there's so many numbers that would get random visits
Would be good to at least verify some of them, or you get 57 being a prime
It does a full prime factorization before identifying if a number is prime, so it's thorough
Hm
That's true, I should add taxicab numbers lol
anamono
i assume the latter because C is defined as a complex number?
since C is complex I'd assume Re(entire complex number)
same
who tf decided to have reduced and irreducible not mean the same thing in algebraic geometry
PROPAGANDA² 

small thing
Hui and Grigor are going to play a game with the following rules.
(a) Hui begins by placing a knight on any square of a regular 8 by 8 chessboard. Grigor moves the knight first.
(b) Hui and Grigor alternate moving the knight, but they can only move the knight to squares that it has never been to before.
(c) The player who cannot move the knight anymore loses. With the correct strategy and perfect play, either Hui or Grigor will always be able to win. Who has the winning strategy?
i need a hint
a small one
anyone??
Since this seems like a game theory question, maybe #proofs-and-logic would be better
We don't really have a channel where game theory fits well
i never knew that was a channel here
@solar hound Are you done with your website and can you send a URL if you are?
I'm not done with it
RYC for moderator! Yes!
I still think it needs more
Before I can confidentally release this version of the site
Is it close? Or do you have a beta version?
It's close
But I still don't want to release it until it's 100% polished
Can you update me when it is finished?
If you want, a previous iteration of the site is available, but it's no-where near as good
If I remember lol
Yes, do you have a URL?
But this is the previous version
It's not the remade version I'm working on
The new version will be so much better
That is still very cool! Good job!
Thank you.
Can I dm you to keep with updates? (I don't know why but I feel invested now.)
Sure ig
when is $\phi$ vs $\varphi$ appropriate
anamono
because (as far as im aware) i have yet to see phi denote anything other than some variable
Meh, interchangeable
dammit
Angle, homomorphism
@cyan goblet different notations are basically picked according to conventions and preferences. Just be consistent and do not mix them together
anamono
Umm
I would just never use epsilon and always use varepsilon
Tbh
Absolutely only use varepsilon for your usual small epsilons
Some people forget to and they are evil

I define \eps as a macro for \varepsilon
would i be stupid to just renew command \epsilon to \varepsilon
dope ty
Yes


This URL looks like a virus and I'm afraid to click on it.
wtf is this
just another troll vid
i don’t lol
every time you learn something try explaining it
and word it so that you can fluently explain
this proves mastery
that actually the reason why I take notes
i dont write notes, but i do scratch work
the truth.
Mathematician Moon Duchin answers the internet's burning questions about mathematics. What actually is an algorithm? Is it possible to explain Pi (π) in words? Is geometric group theory just Anabelian topology?? Moon answers all these questions and much, much more!
Still haven’t subscribed to WIRED on YouTube? ►► http://wrd.cm/15fP7B7
Listen ...
lmao
she didn't even explain pi
"ratio of circumference to diameter" is not mentioned at all
like why is that not the first thing you say
Is folland good to prepare for QR exam in real analysis?
Yes but who fucking wrote this video description
They just took random questions from quora and stuck them in the description
lol
those were literally tweets in the video
(including the anabelian topology one)
Does anyone know why the line integral definitions of divergence and curl aren't taught often
I think they're far more intuitive and don't depend on your coordinate frame (this is particularly important because you learn curl and divergence in so many different coordinate frames).
You need to be well aware about Differential geometry, differential forms, exterior derivative and Stokes' theorem to make a full meaning of an adapted intrinsic formulation
But yes
The same goes for surface integrals (Stokes theorem)
We have some slighly non rigorous proofs for divergence and curl tha work wihou differential geometry
t on my keyboard has broken
my uni uses folland for the real analysis course meant to prepare you for the qual. I would say that it prepares well (but this is university dependent)
I’d say picking up something like royden or stein-sharkarchi might help you if you see a concept in practice exams that isn’t covered in folland
yeah folland is used here too
and people advise stein and shakarchi, etc
i think that one rudin text does both too
i used it a little for my complex analysis class
our uni uses it for our PhD analysis courses too
@austere hazel Kinda wish people would look up resources on stuff they don't understand first, because I literally Googled "point slope to slope intercept form" and that was one of the first results
google is by far a very uncommon common sense skill, i've found
Same, and people need to Google first
yes, yes they do
Literally all my solutions, I Google first
My university also uses folland but I don’t like it
so is reading
but sometimes people want to be told by a person rather than read and it’s understandable
The mysterious thing is the process of reading still occurs via discord
my courses provide pdf lecture notes, so the only thing I do is write up a big list of all the significant theorems/propositions for reference
so that I can look up a theorem in my 5-page book of theorems instead sifting through the of the 50 pages of the book/lecture notes, where most of the space is filled by explanations/examples/proofs
i write notes
down of formulas and ideas
but mostly its just to get the topics into my head
i literally never look at them again
after writing them
this video was really bad
i dont know if it is wireds fault or the presenter but god nothing of substance was said
didnt even explain pi 
yet wrote down that awful looking identity
odd behaviour
all the comments that are like "im a math major and this is so true
" make it worse
also opening with that clip of her being like "you don't need this" 






Hello I'd like to ask for tips on dealing with math anxiety, I just read a report on it and it seems I perfectly fit the bill. Any recommendations on starting my journey? I mostly have to do it alone without the help of an educator. I feel really intimidated and scared and I know it's ridiculous.
I really want to love math but fear is overshadowing it
you good my guy
no fun allowed
this is the kind of stuff highschoolers point at and say hey look i dont need to laern this
idk i think its bad if u r in an authroity positon to say that without any qualifiers lol


-9
Given discussion, dx 
dx < 1 rip you
1.000...001 then 🙄
1-10 is -9
shut it shuri 
I'm not sure how helpful this will be, but my suggestion would be make sure you're not viewing struggle as a sign of failure
The only people who haven't struggled with math are people who've never seriously done math
i would suggest getting good
So when something isn't making sense right away or you're struggling to solve a problem, don't beat yourself up about it
Because that happens to literally every person who studies math
I'll try my best to rethink how I deal with struggling, all my life I've been in a top class with super smart kids and things just came so naturally to them. Wasn't far off that I thought I was failing for my pace
I also thought only smart kids like them could do it
I've been trying to use math this way, I'm redirecting my impulses towards learning math
well im sure things come more naturally to terrance tao than to me when studying analysis but thats just a depressing way to move forward and enjoy things in life
My take on talent in general is that the most significant "innate gift" for a pursuit you can have is enjoying it
i think its very natural to feel this way and i feel this way too sometimes but you have to realize that there is more important things to focus on for your own well being
if you feel sad by someone being better than you math is not it
there is people here in hs who are already better than me lol
The way to get good at anything is by practicing it a lot, and the main obstacle in the way of practice is it takes a lot of time and it's tedious as fuck if you don't enjoy the thing you're practicing
just find what you enjoy about math and focus on that
thats how you build passion about it
and as he mentioned
so in my experience the environment of "i need to match the super genius kids around me" tends to lean someone towards the "nonstop study to catch up" kinda thing
practice makes perfect
which then is flawed because
when you nonstop study, your efficiency actually goes 📉
Fuck
so then even when you indulge in something interesting, you have that same pattern
so take breaks and explore other hobbies too
I've spent my whole life in that latter group :')
for example, i like to do gardening
imo the main thing that the "talented" people have is they really really like the thing they're doing
So they spend a lot of time on it
so when i've studied for a while i'll just go outside and touch some dirt or someting
And get a lot of value out of that time since they really enjoy it
so you can focus on math if you'd like, but be sure to enjoy a lot of other things too
ye he is right
if you're passionate about something you'll probably do better than most people 95% of the time lol
that way youll develop a healthy relationship with math, with your work ethic, and with yourself
And that time commitment is what ultimately matters more than any "innate ability"
So the takeaway here
i made that number up but you get the point
I want to fall in love with math but it feels like I've gotten on the wrong foot and have a wrong view on it, hence the fear
Is that if you care about being good at something enough to put the time it, you will get good at it
rediscover
Yes i love his channel
3b1b does a good job at illustrating the beauty of math
takeaway is do it with passion or not at all
I'm really inspired by him, he's the reason why i want to relearn and confront my math anxiety
dope, then the next step would be to slowly start introducing yourself to new math concepts
or relearning ones that you may not have a clear understanding of
Or to put it another way, the mentality of "I want to do X but I don't have the talent for it" doesn't make sense because wanting to do the thing is what talent is primarily made of
i am being extremely realistic
by saying that you cannot achieve perfection through nonstop study
and will instead hit burnout
I think anyone can be really really good at almost anything if they put the time in to practice
time commitment yes, nonstop commitment no
That's kinda what I'm scared of finding out, what if math isn't the right fit for me
what most people seem to forget about einstien and newton is that
and im not saying this person has to go and become the next einstein or newton
Me giving 100% into doing it
they really loved physics lol
im giving them a chance to just discover something new
i mean, simplest answer is jus that it's not
there is a reason they invest that much time into it
and there's a lot of things outside of math that may be something you love
Some people have insane gifts, but the only thing that kind of gift lets you do that you can't without it is become one of the best in the world
and it won't be a matter of "you weren't born with great math skills", it's just that math isn't a great fit for you
With the right amount of luck
and that's okay
i'd like to believe its just that they are "born different" but they simply had passion and some talent and they worked hard to improve upon it
i would love to do wildlife conservation but i tried volunteering at conservation centers and it wasn't really my thing
so if you've got the free time, go out and explore math
and if you like it, great
and if you dont, it is what it is
if you decide that math isnt for you, you will walk away with a valuable lesson
There's no point worrying you're not Euler if you aren't aiming to be Euler
you won't have "wasted your time" pursuing something you wanted to get better at only to discover you dont like it
you will have instead learnt the lesson that sometimes you have to test the waters before you dive into them
the only reason you need to do math is to love math
Because you are good enough at math to be however good you want to be
What if I learn to love it so incredibly much but my skills don't fit to do it
I'm saying that is nonsense
^
i 2nd that
there are plenty of ways to reach a goal if you truly love it
kinda why this server exists imo
That's reassuring
Loving it so incredibly much is what it means for your skills to fit to it
This video has a list of books, videos, and exercises that goes through the undergrad pure mathematics curriculum from start to finish.
REAL ANALYSIS
Book: “Understanding Analysis” by Stephen Abbott.
Videos: Lectures by Francis Su (https://www.youtube.com/playlist?list=PL0E754696F72137EC)
LINEAR ALGEBRA
Book: “Linear Algebra Done Right”...
this is a nice little video
6 hours
10 minutes long, and pretty good
I wish I could study for 6 hours
I can do all nighters when I really need to but i know that's not healthy
bunny i walked into uni with barely any calculus knowledge and no proof writing skill beyond hs geometry or anything beyond hs really and i can tell you that im in my 2nd year rn and i am doing really well in very hard subjects because i love doing it lol
Oh oops i havent tried doing math for 6 hours but in general for school i do 6 hours of self study
adding onto what james said
What are you taking rn james ash
over 50% of incoming students to harvard's CS department walk in with no prior experience of programming
actually i think it's greater than 50
metric spaces ,bilinear algebra,probability,calc 3, intro graph theory, odes
Ok but also Harvard 🤮
yes in 1 sem
Holy
Is this the not liberal arts college experience
I've never taken more than 2 math classes in a semester
lmfao its not pleasant but i manage
Yeah that is fast
I feel like that’s a fairly universal experience tbh
The more in-depth you go the more you realise how much there is to really know

Thank you everyone, truly. I'll keep trying. I hope to fall in love with math as I learn more about it.
the best part about math is the grueling parts
when i'm having fun, something's wrong
does anyone have any good resources on 3d vectors
coz im struggling a bit to learn it properly
a yt playlist would be v helpful
The only thing separating multivariable calculus from ordinary calculus is this newfangled word "multivariable". It means we will deal with functions whose inputs or outputs live in two or more dimensions. Here we lay the foundations for thinking about and visualizing multivariable functions.
video library talking about vectors and matricies in 3d space
- some other stuff
computations build character
any other's that directly focus on it?
not sure if know of any resources that explicitly focus on 3d vectors
oh

What why is that so true lol!
Almost as expected 
anyone here bilingual?
Yes
not being native english speaker moment
yeah
Since I still have to use very limited amount of English off screen
hm?
bilingual means you speak two languages
I don't really "speak" English a lot
certainly you are able to
ok, i have no idea what it means to 'speak' a language
Yeah at least for my CV I can pretend I'm proficient with English
when the interviewer switches to english mid conversation

Interviews for internships have been an actual metric for me to gauge how far I can hold a conversation in English
its really weird for me to talk english with other germans
im rather comfortable talking english but i never know how much they understand
Aah
it was super weird in school
I just start supersonic rapping in English
With the onus to understand on the listener
time to go to the US for a year


:
"okay" might be a fair description, yeah
I still feel some nervousness meddles with what comes out of my mouth
its pretty diff with me
i start speaking and then i start stuttering coz my mouth cant keep up with my head

you will learn quickly once english is the only way to communicate with people around you
true
my final highschool year we visited london and some guy in my class was robbed
and unable to talk with police or wtv
so i had to do it
Yeah, that's true
talking with natives is a good way to learn

ye, there were almost no natives in london 
Lmao

Bruh 
so yeah, this was quite the odyssee

lmao
anyways, in the end we had to visit the embassy
and this dude had to finally talk with someone
and he talked in really not great english
and the other guy noticed and told him to just talk german its fine 

moral of the story: look after your belongings in foreign cities
and learn english
i look after them in my own home
😭
Can you get by with German officials talking in English?
no idea
my guess would be no
if you are nice you can probably get hold of one who speaks english well enough
there are lots of people in germany not being able to speak (any) german
problem is they dont speak english either
What do they speak?
wendish
Makes sense
tongue of the wends
Actually... idk if this is in Germany or Austria
But apparently there's a rarely spoken language called kandis (spelling?)
Oh I think it ends with eszett
kandiß
whats
why are you reacting with random emotes
i dont
You seem... more familiar than my American ass
then you should ask what kandis is
Ah
go ahead
blo what are you doing
I don't get it
Anyway Shawshank wanna know about it?
Bruh what's with this memeing
about kandiß ?
Yea
sure
Kandiß dick fit in yo mouth
I'm sorry 
yooooooo
Witness the master at work
immense pain in my lower intestines
Anyway my degeneracy aside what's up? I haven't seen you around the server much before Shawshank
What are you interested in?
I am new here yes, i came here initially to get help with finite automata concepts here
yes im interested in CS too, low-level concepts
good thing i didnt ask about it and read the messages below
Shyshu you actually inspired one of my better jokes
You remember that one time we were having the convo about Jotaro?
i dont really remember no
Oh
my memory is filled with random ass chemical equations i cant remember stuff well
Well you know that scene where he's walking to that other guy?
I forget his name
But he's like oh come as close as you want
i randomly asked here about anyone knowing haskell, someone pointed towards mniip and i saw his github and now I randomly ask about binary exploitation stuff from him in #chill
You're the one who showed me that scene

i havent seen jojo or any anime other than dr stone for that matter
are u confusing me for someone else

there are lots of turkish speakers and now also arabic
The goal is to somehow build up to a convo about how French numbering makes literally no sense
sababa
there is a german-russian minority too but its not that many
ANd get them to say "dix neuf" (the number 19) in French
hmmmmm
that does sound somewhat familiar to me actually
Aka deez nuts
But you have to build up to it so it's not sus
So here's how it would look like, let's say I'm the one getting you here
Shyshu how do you say "God" in Italian?
dio
Dio like deez nuts

FUCKING SUBVERTED LET'S GO
thats really nice lmao
its borderline offensive
these are offensive internet memes, yeah
Hmm, inappropriate I'll grant, I hesitate to say offensive
But wow I had to work really hard for that one there
i knew u were building up to a deez nutz joke the moment u said god in italian
Tru hence why I was hoping that you'd think it'd take longer by telling you the punchline
Reverse reverse reverse psychology

i have kinda dumb question but want to see ur answers
not homework related
but math related
if there is infinite numbers between 0 and 1, how are we able to reach number 1? when all decimal places are resetted to 0
like numbers would be 0.xxxx where x /= 0, but then all xs will become 0 when it reaches 1?
that means the infinity numbers between 0-1 came to an end?
We can’t really “reach” 2 in that sense
There’s no notion of “the next number” once we introduce decimals, as far as I know
i meant 1 instead of 2 sry
real numbers dont rly exist
bruh wat
Reach in what sense?
I can write 1 and "reach" 1 in a sense
You most certainly can't start "counting" from 0 and reach 1, enumerating each real number in between
in other words, how does number 1 exists when its infinitely numbers away from 0
i dont see how this is an obstruction
you should be more worried about the fact that all the numbers between 0 and 1 exist
whats the first real number greater than zero
first?
the first real number to satisfy > 0 condition
there is none
There is no such real number
Suppose x were to be such a real number
Then x/2 would be less than x and still greater than 0
Contradicting the fact that x was the "first" such number
im so confused
It's okay, the idea can take some time to absorb
If you like to think geometrically
Your "first" real number would come to the right of 0 on the number line, right?
Now since these two points are not one and the same, there's some distance between them
i understand this. but i think number 1 depends on 0 somehow
Depend how?
it basically means for any number you choose as close to 0 as you want, you can always choose a number closer to 0
conceptually
real numbers are supposed to not make sense if u try to count them
i think its existence cannot be understood without understanding zero
thats why theyre literally called uncountable
😭
bb ub but if the turtle can always b bhh b then how can hercules win ?.?/??
the tortoise paradox is not about uncountability
I can assure you the way real numbers are "constructed" is consistent and devoid of paradoxes as far as we know, but it takes some technical machinery to understand how they come into being from simpler numbers (rationals).
its abt misinterpreting the idea of tasks
yh
the error is assuming that a sum of infinitely many numbers is necessarily infinite
the question seems less about uncountability
and more about how an infinite number of points have finite measure
@rationals have that property too right?
there isnt really a question here tbh
oops. newbie here. i meant to sddress sean
I think I can vaguely sense the problem here but can't give an explanation unless Lam is familiar with limits
the concept of Convergent Sequences did not appeal to the common greek
that paradox would probably
Maybe Lam wants to think about discrete jumps starting from 0 that will eventually lead to 1
there is some problem, but i think lam just needs to think a bit more, identify their issue and come back then
i know some of it
clear some things up
people unloading their knowledge will be semi-helpful
if smth just doesnt feel right and is very confusing
Yeah, fair enough
smtimes helps to just put it on the backburner
Throwback to me realising Cantor's proof of uncountability of reals actually makes sense months after seeing it for the first time
i had a crisis abt epdel the first time i learned it for abt a month
came back to it after a year and it was a lot clearer
bc of the simple fact that the more ukno the more u see
My epdel crisis will never end
is 0 a part of 1?
wdym
"part"?
intersecting conversation. so there is not a way to explain this without getting deeper in more advanced math? btw hello, i just joined and know some calculus and some discrete math.
interesting
Hello K-Son!
hello ❤️
can number 1 exists without 0s? for me i think 1 is the sum of zeros like 0.x + 0.y = 1
ure not talking in a way that makes sense
Exist in what sense?
idk how to explain:((
I can declare a set {1} and say 1 exists (foundations cranks please steer clear of this remark)
read some stuff on how the reals are defined
and try to pick up how math ppl express it
holds the urge to rec Tao's Analysis 1
just historically the invention of 0 comes (way) after the invention of 1
the number 1 is just some abstraction of a collection of 1 thing
Good point
u just need to broaden ur idea of what "number" means
alright my head is heated, that’s enough math for today bye!
finally
take some rest pal

you mean forgetting theorems is normal?
fuck that actually makes sense
while you're learning them? definitely
(for me)
examinations provide formula booklet for a reason
u just need to know how to apply a theorem in our school, they give u the formula for it in a formula booklet
nice username
thx
if you're doing a maths course then you'll probably want to know the exact statements + proofs of the important results for the exam, but while you're learning it's very normal to forget these things
do you think knowing how to replicate those proofs correctly is important for a self learner?
depends on the theorems, sometimes a proof is really central to the idea
also depends on if you're learning maths for its own sake, or to apply to something like engineering
It is ultimately most important to understand the big ideas behind these proofs rather than the details
The big ideas might inspire you when it comes to proving other things, and the details you can always look up
But if you don’t know the big ideas, you might not even think to look at them
ive always wondered... properties that are inductively demonstrated to be true in finite cases, why does that not necessarily transfer to infinite cases?
because infinity behaves weirdly
i can maybe understand for uncountable infinity
but like..
if you have a normal number in a given base, right? youre guaranteed to find every sequence of finite length somewhere in its decimal expansion
iirc normal is about the frequency with which the digits appear
Objects that are not finite often have "infinite" room to wiggle around, and that dramatically changes the applicability of results.
not the guarantee that every finite pattern shows up
you can have very regular normal numbers in that case
am i misremembering
Transfinite?
I don't think that is strong enough to guarantee what you want
because yeah if thats the definition of normal then some fractions are normal
"If a number is normal, no finite combination of digits of a given length occurs more frequently than any other combination of the same length"
from wikipedia
normality is an interesting property, i usually think of it dynamically

thats literally the definition
maybe this was a bad example lol its the first one i thought of
how about like literally anything from group theory
like idk fundamental theorem of abelian groups
not that you can do that inductively
Every finite number is finite. Proof: Let n be finite. Then n+1 is finite as adding 1 to a finite number will still be finite. Thus every infinite cardinality is finite.
i guess
Let A be a finite set. Then A has no proper subset of cardinality A. Proof: supposing this is true for sets of cardinality n, assume a set B of cardinality n+1 has a proper subset S of cardinality n+1. Then we may remove a point from this subset from B, and we will have a set B-x with a subset S-x both of cardinality n and with S-x proper
Therefore no infinite set has a proper subset of the same cardinality (which is a contradiction)
?
those are both counterexamples
they aren't even that complicated
If you want the real reason this works
that you cant construct a set containing itself as a proper subset, thats a consequence of the literal definition of a set
as distinct from a class
That is not what I did
In ZFC every infinite set has a proper subset of the same cardinality
For example, you can remove 1 from the natural numbers
you still have a countable subset
but its proper
oh i misread
The real reason this does not work is that an inductive proof gives you an algorithm to get a proof of the fact for any fixed n by just starting at the base case proof and working up
This terminates and therefore gives you the desired proof
There is a process called transfinite induction that can be used but it requires an extra step to get around this issue
makes sense
i think maybe invoking like zenos paradox makes it clearer
like i wouldnt say that it terminates
terminates was a bad word to use, the point is you have some way to "get at" each n
whereas you can't "get at" the infinite case
but that an infinite number of finite steps will not "reach infinity"
you need additional machinery, like a limit or an infinite set
that is essentially how the transfinite process works
You have two things to show, namely that if the statements holds for a then it holds for a+1, and if it holds for all such a then it holds in the limit. then you can reach all the desired ordinals
what about the smallest ordinal that is not the limit of a countable collection of ordinals
i guess it would be the supremum of a collection of countable ordinals
i guess im imagining that there must be some level where transfinite induction would break down because you need a meta "all such a" sort of thing
but not necessarily, if its general enough
every ordinal is either a limit or successor
Nice dog
yep
this collection itself is necessarily uncountable btw
right
of course one doesn't have to choose a countable increasing sequence of countable ordinals to take the supremum, one could just take the set of all countable ordinals and take its supremum, it's not necessary to "get there" with a countable sequence
the magic of the supremum
but you do need a set
ya
so you couldnt take the supremum of all ordinals
no way jose
which i guess is obvious lol
Well you can read this the other way too
your argument proves that the ordinals don't form a set
because suppose they were a set; then you could take the supremum, and this would be an ordinal greater than all ordinals in the set, a contradiction
$sup_{\omega}{\text{all ordinals }\omega}=X$
LoLDongs
boom
got any other problems for me
just solve for x
something something, supremums always exist
oh thats why i said you cant take the supremum
because the ordinals dont constitute a set
how else would you arrive at "you cant take sup(all ordinals)"
Well, what I think you're saying is
- The ordinals don't constitute a set.
- Therefore, it doesn't necessarily make sense to take the supremum of the class of all ordinals.
And what I'm saying is:
Hmm, I'm not convinced; how do you know that the ordinals don't constitute a set?
Well, you can prove it by running the argument in the converse direction. - If a collection of ordinals is a set, it has a supremum, which is also an ordinal.
- But the collection of all ordinals has no supremum. Ergo, it is not a set.


(I guess the larger point here is that I don't know how to prove "the ordinals don't constitute a set" without assuming "every set of ordinals has a supremum", but I do know how to prove "every set of ordinals has a supremum" without assuming "the ordinals don't constitute a set")
no cap
I mean the set of all ordinals would itself be an ordinal
Since that's how ordinals are defined
But then it wouldn't contain itself
Sure, one might assume that for the sake of a contradiction.
(Here I am assuming that "being a set" is part of the definition of an ordinal.)
I mean is that not just a proof that there is no set of all ordinals
I mean also if there was then couldn't you use that to get $ZFC \vDash ZFC$
Yeah, you're right.
I got to the conversation just right now
Worst Geometer NA
I don't think I know what you're trying to say here.
So the issue I think is that if one constructs the ordinals in a reasonable way (say, VN ordinals) then you observe that you can take any set of ordinals and union them to get a new ordinal that is no smaller. You also observe that the successor operation is necessarily larger. Then you assume you could take the union of all ordinals. Then this is a new ordinal, larger than all others. But that ordinal +1 is larger, which is a contradiction
Is the question to prove that there is no universal orjinalini set?
something something too large to be a set
Ordinal
You can edit your posts nevzat. Haha.
Well there's a proof that if k is an ordinal then the collection of all sets of cardinality less than k is a set
iirc
Yes, this is known.
Isnt this burali forti paradox that you guys are talking about
So if K was the largest ordinal then that would give you the set of all sets
Again, I got to the convo late
Hence set model of ZFC within ZFC
Yes, it's closely related to that nevzat, but each person here is I think bringing their own comments and questions, there's no one single issue to be resolved
Or really just whatever contradiction you want to derive from the set of all sets
Hahaha. This is the strangest proof I've heard that the class of ordinals is not a set but I guess it works, in theory.
Assuming one takes Godel's incompleteness theorem and the apparatus of model theory for granted
Yeah
There are much easier ways to form a contradiction from the set of all sets
Just comprehension into Russell's Paradox for example
The godel thing is somewhat intuitive to me though
Sure, whatever floats your boat
Because of the whole inaccessible cardinal giving you a model of ZFC thing
wait back to the sup thing how would you show that the class of all ordinals does not have a supremum
Add 1
would it just be like
because the sup would have to be in the set?
Yeah, basically. Or sup+1, whatever it is to make the proof work
Nice dog
summer is a good pooch
who's more of a daddy
newton or euler
i say newton but my friend says euler we're in an argument
euler was legitimately a dad, newton never had kids
Newton was kind of a huge dick from what I’ve read about him
yeah
Newton said on his deathbed his greatest achievement was dying a virgin



