#serious-discussion
1 messages · Page 57 of 1
funnily enough over the summer for my reu we read out of cox little and schenck for toric varieties :3
hello
what would be funny is if you weren't even reading cox little o'shea and just chose an arbitrary book and were like 'ok ill solve an exercise from this book' without having read it
cox little is a funny name
cox-zucker machine
Yes, mostly because sometimes when I'm too lazy to actually start working on my assignment, I just copy the problems to kickstart the effort
By the way afaik I can draw graphs with TeX right?
I think you need some extensions
Also, why not latex instead of just plain tex
Who hurt you?
i'm researching the difference between tex and latex now
i just wanna mess around but idk which one to choose
ig latex is better
Figure it out
tikZ makes it a lot easier
i have a math textbook that i purchased and it was printed in 1911
on the first page somebody wrote their name "George W. Elg"
and I was just thinking how cool it is that even though that person is probably dead, they never would think that in a hundred years from when they owned the book that a person would see their name and get curious about who they were
does anyone have recommendations for a good intro to signals analysis textbook. I already took the class but basically learned nothing cause so much of the math was glossed over (engineering classes :D) so I want to review it again with more rigor (but still be useful)
LaTeX is TeX + some libraries. Using plain TeX is unadvisable since you have to define lots of things in order to use it. Just use LaTeX. KaTeX is a program that lets you type a subset of LaTeX on the web; it is not comparable to either TeX or LaTeX, but it is similar to MathJaX.
Thanks for explaining me everything so throughroughly
It just annoyed me that someone had said something so misleading lmao
Lol I see
you have to use latex because that's what most journals and other authors work with in maths
Pretty interesting
https://josephg.com/blog/3-tribes/
Seph
There's an old joke that computer science is a lie, because its not really about computers, and its not really a science. Funny joke. Everyone laughs, then someone says "Yeah but it sort of is about computers though, isn't it?". Feet shuffle awkwardly. Someone clears their throat and before you
You should learn to read asm tho
Knowing what your compiler produces is kinda useful
Don't write asm altho, unless you have to for whatever reason
True
I know quite a few applied math people whose jobs revolve around optimizing algorithms for performance. They mainly code in C++. They don't really care about hardware much though.
I feel like "by applied math" the guy means "people who do FP research"
I guess type 2 would be performance and/or control oriented(the latter is what they tried to imply by saying hardware I suppose)
Actually the 3rd type is very vague
anyone know what type of math we learn in 8th
hey i am taking AIME I in a little less than a week internationally. i have some quesitons about how scores r graded for ppl internationally and how the testing format will look. please dm me if ur taking AIME I internationally.
anyone here know what math we learn in 8th
probably pre-algebra
ok thanks
not really sure though, i would ask your teacher
i do remember doing stuff with money
https://www.youtube.com/watch?v=IP4rhdPIbZs good or bad
Provided to YouTube by Warner Classics
Rondo brillant in B Minor, Op. 70, D. 895: II. Allegro · Vilde Frang · Michail Lifits
Paganini & Schubert: Works for Violin & Piano
℗ 2019 Parlophone Records Limited, a Warner Music Group Company
Piano: Michail Lifits
Violin: Vilde Frang
Composer: Franz Schubert
Auto-generated by YouTube.
I found this really cool function: f(x)=sqrt(a-x)
(f^infinity(a)+1)^2=4a+1 for all a’s that are integers over 1 i’ve seen
did i just discover something that has a name again
but basically it’s taking sqrt(2-sqrt(2-sqrt(2-sqrt(2-…)))) and (that +1) squared =9
obviously that’s simple but 3 becomes 13, 4 becomes 17, and 5 becomes 21
you just discovered sequences
this is one of the exercises in calculus books
prove convergence of x_n and compute limit x_n as n->infinity
(for positive a)
none of the cube roots seem particularly special
i think you should probably go to the math help channel but u should probably either translate or go to an indonesian server
either way this isn’t the right channel
it’s fine nothing wrong! i came across a little rude i apologize
okok new question (doubling down): prove that for any integer root greater than 2, (let’s say b) and any integer value for a, the resulting value of [bth]root(a-[bth]root(a-…)) (is transcendental and) cannot be expressed in terms of algebraic equations that may also include pi and e
terrible conjecture 0/10
if i was on my computer i could actually set theory it but i’m not
Set theory it?
purposely dumb way of saying use correct symbols and notation

The Mathematics of Signal Processing by Damelin and Miller Jr
I need help differentiating e^2 ln x
!help
Please read #❓how-to-get-help
I need help on how I can explain to someone a scenario in poker probability when they refuse to understand it correctly. lol
just don't
Lmfao but I don't have the ability to let things go
and we talk all the time about poker and study it together
Usually making a simpler case that exhibits the same concept works
Yeah but I do that and he just basically says: no but counter "argument"
Put it to the math
idk he is literally running an experiment with actual cards, the result is going to support what i am saying, and he is going to interpret it wrong, lmfao
Is this something complicated with spread-of-cards probabilities
i can explain the actual scenario if you like, but would probably have to be a call, as its way too much to explain in msg
its like
the chance of opponent having X hand
based on your cards making it more/less likely
Is this blind or in the turns
on the river haha
I'm not good at poker math but perhaps I can help
the stages of the game are called preflop, flop, turn and river
preflop is before the middle cards come out, flop is the 3 cards, turn is the 4th and river is the 5th
O that's hard. Probability of his cards are only reliant on the way you bet, not your cards
both
Because he is guessing your cards based on your bets
Well yeah
For replacement cards
what we are talking about is a scenario where at the end of the hand, the opponent makes a big bet
and for this particular opponent it means either he has a very good hand, and you lose
or he is bluffing, and you win
so there is a thing in poker math called combinations (comes from the general math term), and you work out all the combinations of hands the opponent can have
Or you fold, and loss less
and if you have certain cards in your hands, it makes it more or less likely that your opponent has stuff
because maybe you are worried about the opponent having KQ, for example, and you have a K
now its less likely he has KQ
but if you have TT, and his bluff might need to have a T, you make it more likely he has KQ, and less likely he is bluffing
in effect
Yeah
so basically, he misunderstands when his cards make an impact on his opponents hand
can someone help me with probability
probably... hehe
prob of winning is 2/23 prob of losing is 7/23 how many games were not played
What does he think? That there are 5 kings in a deck?
What you're talking about is 101, no offense intended
!help
Please read #❓how-to-get-help
Nah, its like say opponents bluffs are exactly 88 or 99 (so if he has those you should call) and his value hands are like KQ/KJ/KT where both are diamonds
He thinks that if he has King spade + King heart, it makes it less likely the opponent has for example KQ of diamonds
because he has kings in his hand it makes it less likely for opponent to have a king
It doesn't, if you calculate for king of diamonds
but he doesnt understand that opponent having exactly the king of diamonds is independent to the opponent having the king of spades/hearts for example
in other scenarios where you want to worry if the opponent has any KQ, then you have KK affects that chance, but not the chance he has the King of diamonds specifically
Ask him if having a jack lessens the chance of having a queen
and i have explained to this a hundred different ways but he doesnt get it
my other version was lets say i have the 2 of diamonds
and I am worrying the other guy has a diamonds flush
When he says no, say, "but a jack and a queen are face cards, so he has less chances for a face cards"
but I know he never plays with a 2 of diamonds (cuz he would have folded)
does this impact his chance of having a flush
and he is like no
and im like face=palm
lmfao ill try that
Your friend doesn't understand independence
yes
Well the only way I know to fix that is to explain it more formally but that doesn't sound like it'll work
Try stuff like
what i did was show him the probability of som eone having the king of diamonds in there hand
and we did it twice - when I have KK and when i have AA
and the chance is (Obviously) the same
My analogy doesn't work nvm
but because in example where we hold KK the total number of kings the player would have was twice as many in example where we hold AA, he incorrectly follows that through to the King of diamonds independently
Have patience
Probability is almost hard wired into our brain and in the wrong way
Mistakes like his are apparently common
He is running a live "simulation" where he gives himself KK (black kings) and then deals in 8 people and records how often a king comes up and how often the exact king of diamonds comes up
then repeating it with AA
Let him work the numbers again and again till he understands
and its going to be identical % for both for Kd (give or take variance)
but he is going to then say (and I am certain this is coming) that but since they have kings half the time when I have KK, the chance he has the Kd is less
its two fold - he is misunderstanding independence AND he is incorrectly assuming that because the total number of hands the opponent has before the hand starts impacts his hands at the end
The second misundertanding is like
Say the opponent could make a flush with KdKc or KdKs or KdKh. Then obviously us holding KsKh impacts opponents chance of having those Kd combinations. However, if the opponent has played such that it is impossible (or extremely unlikely) that he holds pocket kings himself, this does not matter at all. And though he understands that concept in general, he is basically passing that on to the Kd combos when he says "its less likely he gets dealt a king, so even though the kd chance is the same in THEORY, he doesnt have it very often in practice" and im like bro theory = practice #mathsisalwaysright lol
So tell him that he run the numbers already. If his understanding is at odds with reality, he needs to fix it
Or he can just lose money on the table. Other player will be glad
Lol
I don't understand
If you ruled out kk by playing then there are no kk
Ah I understand
He's mixing two different scenarios
Yeah
Like in total there are 6 ways to make KK out of the four kings
If I have KK now there is only one way
These “ways” are called combos
So if I hold KK and I think opponent might have KK or some other hand
I can count his one combo of KK and then his other hands
And this tells me (fairly accurately) the chance he has each hand
Yes
But he is basically assuming him@having KsKh further affects the opponents ability of having Kd8c, or Kd9h for example, because it includes a K
Well look it's taken us thousands of years of gambling to get past this stuff. People used to think 66 is as likely as 1 5 in dices and my brain keeps telling me 3 4 is more common than 1 5
You've got an unique advantage in that you can tell him that the table doesn't care and that he run the numbers already
Is learning R programming worth it
yeah probably, it's good for a lot of analytical tasks
I'd lean that way over python if I were starting out in STEM and not focusing on programming for non-math purposes, in which case I might lean towards python and supplement with pandas (which is like a less-convenient OO version of a data frame).
learning one once you know any programming language* is trivial. They're not very big as core libraries.

No? numpy is pretty good
prolly python
if you get good enough at programming, it won't matter
if you stick with one you'll pick up the other fairly quickly
so when in doubt, just pick python coz it's way more useful
and makes up for a good competitor to R when we're talking purely about analytical tasks
I see. Thanks for the advice, man.

Agnes: "I have 5 clue sentences."
Ramon: "I also have 5 clue sentences."
Set: "Ramon doesn't have 5 clue sentences."
In a game, Agnes, Ramon, and Set each gave one clue sentence to Insi. Among the three, one person gave the wrong clue sentence. If Insi can guess who gave the correct clue sentence, then Insi wins. Who gave the correct clue sentence?
also, is this math related?
if so, what branch of math deals with this kinda questions?
yeah, that's what I'd recomend
I don't see eye to eye with darq here. I'd say pick up python first only if you're unsure of your field(like software engineering or cs vs maths or applied sciences).
well, if one person gave the wrong clue sentence, two must have given the correct clue sentence. If insi needs to guess who gave the correct clue sentence, and each sentence is different, then there is no one correct clue sentence, it's a contradiction, and the problem isn't consistent. Discrete math
I wouldn't recommend R to anybody as a first language
If you're planning to use R and only R for the rest of your life, perhaps, but really?
I dunno man. It's the de facto standard for statistical & time series analysis afaik.
the reasons are numerous.
I don't think anybody will be able to avoid learning both, if they're in applied sciences, because of the package ecosystems having slightly different emphases, but you gotta start with one.
In terms of learning support, I think python has much more
Stuck? SE can solve it 99% of the time
that is probably true. I don't think it necessarily has more learning support targeting deeper applications.
from a bioinformatics background, biostars had many more useful discussions than SO.
or SE.
and within those discussions, R package use was predominant.
Just a bit curious, but is anyone good at mental math and knows techniques for it? I heard mental abacus is pretty good but idk if it’s outdated. I’m tired of always using a calculator for basic stuff nowadays haha
for data science i like python
learn both
they are straightforward anyway
mathematicians don't have to master them
but if you know the principles of a programming language already (like C) then any language is just pressing F1 or reading the docs to get used to
If you are not doing FP, that is
yeah I mean it seems to me that all data science, unless being done by an amateur, is best done by a functional approach. R's default approach is functional, Python's is OO.
some python libraries try to shoe-horn the OO baked into the language - list comprehensions, pandas, subsets of numpy - into functional paradigms. But it's not like the design of the language was meant to economize using those libraries' functions.
the real constraint isn't often about best (preference) but popularity
and what other mathematicians use
I guess I'd say that's domain specific
python could be suboptimal as heck for a problem but if it's about communication with mathematicians then usually people pick something others can understand like python
or even matlab, since most mathematicians know matlab
I duno, I figure if you boxed up octave and matlab common concepts alone you'd have a much greater correspondence to R than python.
in fact, learning R once you know octave or matlab is much easier than learning python's OO bs
R isn't hard to learn
yeha I was surprised to hear that
I find it much easier to communicate how to do any analytical tasks' details, if details are required to be communicated, in terms of R
the syntax is great and it doesn't continually push an object layer over everything
at least not from the user's perspective. It hides those details and allows functional* access to whatever data you need.
what do you guys think of julia? i was thinking about learning that
also there is so much stuff on the internet for python
Like, most of my work has been in fairly well-documented and supported languages
then I pick up Raku (perl6) and suddenly it is very hard to find good resources
or libraries
But something like python, you will find a library for anything you need
@flint island hello how do you do
oh henlooo. I'm existing
@flint island cat pic?
floof
aww
So cute ❤️
awwww]
So I was playing around in desmos, and was thinking about music theory a bit. We use a 12-tone system, where there are 12 equally spaced (logarithmically) notes between the unison and octave. Out of curiosity, I did some desmos magic to get a graph of how many cents off the closest note to the perfect fifth is given how many tones are in your system, and ended up with... This.
(Link copied by hand from computer on phone, may be incorrect tell me if it is)
Does anyone have any idea where these patterns come from?
it looks neat
That's all I can say
Fair enough
I think it makes sense for the maximum to relate to logC(2^1/x) and it almost looks close, but it looks a bit more restrictive
Might be 1/2 * logC(2^1/x)
That seems about right, and I guess that makes sense. Idk why it's 1/2 though.
Ok, a bit of derivation shows that this is equal to 1/x * ln(2)/2*ln(C)
Interestingly that means that it's equal to its inverse, so to calculate how many tones to be guaranteed to be within a given accuracy is the same as the minimum accuracy when using a given amount of tones... Assuming the conjecture's correct and it doesn't just happen to fit it perfectly
Why is the fourier space (sines and cosines) important for classifying images using machine learning? Nothing about pixels on an image naively to me seem to be relevant to periodic functions
Do you know about convolutions
Yes
Not within the context of pixels
Ah okay
So basically, convolution just means you're taking some filter and you apply it to a set of pixels, then you move it over by one and then apply it again, then you move it over, etc
So for example blurring is a form of convolution
Ya
It's just convolution with the filter that's 1 in every position like
0 0 0 0 0
0 1 1 1 0
0 1 1 1 0
0 1 1 1 0
0 0 0 0 0```
Similarly you can do edge detection via convolution
And all sorts of other things too
And the human retina system kinda does that
And how is this relevant to sinusoids?
The key is that when you're doing convolution, you have to compute a messy integral/sum
However, when you do convolution in the Fourier space, then convolution is just multiplication
Computer scientists deal a lot more with the discrete variants of the FT right
So what you do is you convert your signal to Fourier space, multiply by your filter, and then convert it back
Yeah the FFT
ah right
Also I think this would fall under more of an image processing, electrical engineering, computer vision, etc thing
So it's not strictly CS
To elaborate more, sinusoidals are the nice functions that serve as the eigenfunctions of your system
my CS is so bad which is why I like learning how people there think of fourier analysis and so on
When you have what's called a linear shift-invariant system and you apply it to a sinusoidal, what you get is just another sinusoidal
So analyzing how stuff behaves w.r.t. sinusoidals is really easy
While the problem is difficult in general
That's why you convert everything to sinusoidals and then back
@storm sage In my book it says
"Wavelets are most applicable when
the input values live on a regular lattice, such as the successive time points in a temporal sequence, or the pixels in an image."
I don't know what a regular lattice is but do you know if/how that information is relevant to what you are talking about?
I think regular lattice just means they're evenly spaced apart
Like the pixels in an image just go (1,1) (1,2) (1,3) etc
@storm sage
I assumed it was this
https://encyclopediaofmath.org/wiki/Regular_lattice but maybe im wrong
ah you're reading about wavelets
if you give me a couple days I can get back to you on this stuff lol someone recommended a book to read through and I've only just started looking at it
to get the disjoint union of two sets, dont you have to assume there is a background physics with time and dynamics and stuff to make it possible?
otherwise wouldn't everything be static
What?
Like do you mean in order to consider the disjoint union of two sets you need to have a brain that exists and follows the laws of physics?
in a sense
it kinda seems like there are 'presumed' axioms that are most of the time 'too simple to consider'
Thats exactly correct
but yet we go super simplistic with stuff like the successor function
Im guessing that the motivation or the big idea of the purpose of set theory or logic may be at the heart of your question.
You are intentionally choosing as simple ideas or properties as possible in order to have a foundation to start reasoning. Deductive reasoning requires antecedents. 'if it is raining then you will get wet outside'. this sentence has the constraint of 'it is raining' in order to say something meaningful. These constraints or antecedents to 'if then statements' or implications are the axioms or first principles.
yeah
'if you wish to make an apple pie from scratch you must first invent the universe'
Yes exactly
just it can seem like shaky ground a bit when we 'know' we can never reach the bottom, so we have to make the best version of it we can
What you are reading about right now is the process of 'inventing the universe'
Yes this is a fundamental issue of epistemology and language
In the field of epistemology, the problem of the criterion is an issue regarding the starting point of knowledge. This is a separate and more fundamental issue than the regress argument found in discussions on justification of knowledge.In Western philosophy the earliest surviving documentation of the problem of the criterion is in the works of ...
but then should we worry about time in set theory or not?
to 'do' or combine anything it needs to be more than a freeze frame, unless its just implied, and often it doesnt seem to be written that way
what if there were time traveling sets?
Theres that one set that only visits on Wednesday
time traveling monoid
In short - you don't need to worry about time when developing the primitive notions required to discuss mathematics. In my opinion, math is inherently connected with language.
We are developing a 'formal' language alphabet and grammar in order to start discussion.
The formal language can be studied using set theory, called proof theory, which does discuss the implicit understandings that textbooks assume when developing set theory but you need to start somewhere.
We've just been doing set theory at our local bit of space-time where time can be neglected
We need relativistic set theory
Damn auto correct
quantum type theory
i did hear someone saying they (sort of) use QFT as part of foundations for math who was some fancy category theorist, dont remember where i read it
what i just said was a joke
turns out not entirely
people are not going to use qft in foundations
they might use something also used in qft in foundations
youre gonna make me want to google it and idk if i have time to find it tonight
it was more of an offhand comment in an interview also
i think qft uses some category theory so like
I'm not surprised there's a small connection
i agree, the language thing is an interesting aspect
@dapper current @alpine kindle maybe i should have instead said "historically during the development of set theory to solve the mathematical foundations issue of the early 1900s they didn't think that time was an important piece of data fundamental to what they were developing nor did people of the time think it was necessary to track or talk about time in order to solve the specific issue of the foundations problem of the early 1900s"
but i just wonder if it could be now
That I have no idea
but gtg soon, gn, maybe can continue another day.. or discuss other things
isn’t it so nice out?
What's a little frost among friends?
Whats the temperature like where you guys are ?
This is Massachusetts
-21C
feels like i mean
warm weather
well it depends on what part of the world you're in obviously... i live in canada so not that -20C temps in winter are normal
celsius ??
yeah
oh that’s -5°F
actually i assumed you meant C as well until you said massachusetts
yea no
and then i realized it had to be F
-30°C
it's actually way warmer here than it used to be
like the fact that we had days in january where it was only -5C is astounding
few years back you'd walk out in jan with it being -25C at least lmfao
it hasn't been this cold in a while
nah i can never remember the formula
-15°f
i don’t either im converting on google lol
isn't it like
how’s canada like ?
5/9(C-32) or smth
canada is alright
maybe
(i am canadian)
no idea
i mean i guess it's good
haven't been anywhere else so i don't have anything to compare it to
is canada hyped up?
From an american standpoint yea
yeah well
guns
Yea
nah jk
guns and funny politics (but we're just as guilty of the latter)
canadians love to clown on americans for having goofy politics but holy shit we're not that great either 
Trump & biden bruh
What’s y’all’s political situations
idk much about canada beside the stereotypes
maple syrup
everyone’s really nice
😂
honestly i might be the only canadian who thinks maple syrup is overrated
you are not
It is lol
thank you!
well i’ve never had real maple syrup
not so sure about the nice part
i’ve had the sugared down american syrup
seeing as i again haven't been anywhere else
i will always reference trudeau doing blackface that one time
who’s trudeau
prime minister here
i assumed so
prime minister is kindve the same as a president correct ?
jusf like the leader
swear i know nothing about other countries
i'm not the politics person but yeah
does vermont have a specific brand ?
no
do they get sap from like a certain type of tree ?
is syrup something you eat or drink?
pancakes, waffles
just making sure because “i eat a lot of it” sounds like you just make a plate of it 🤣
chugging syrup...
oh god
yes
will i get in trouble for saying that 😂
maybe
waffles are better
i don’t like how waffles have rough aspects
the divots never have an even number of syrup / butter/ batter ratio
Pancakes a good fluffy stack 😩
LMAOO
is your pfp a unit circle?
i haven't done trig in so long
i started self studying math last year, i started with trig
i'm currently doing lin alg and i've basically started multivariable and complex analysis
You don’t go to like high school ?
i'm gonna be honest, i genuinely have no idea
google says yes, but no one here has mentioned it once
yea it’s an easier test in comparison to like AP classes
i’m heading to bed but it was good talking to you mate
gn!
the calculus 2 experience
It's mean for your teacher to deduct points for small details
if i was building a bridge, and i forgot my +C
I would be responsible for the deaths of millions
Well in that case you'd probably solve for C or solve a definite integral
But you knew the bounds of integration would change after your skillful use of u-sub, you just didnt write them down till you needed them
deducting points for no dx is so dumb lol
This is so stupid
Sorry ur going through tbis bro
hi
Honestly, I think the dx deductions are fair
agreed.
The small details are the ones you forget when you step away from a problem (or work more generally) and come back, so if you left them out you're setting yourself up for failure.
I'd argue leaving out a +C is about as egregious as getting a sign wrong
Which can have tremendous consequences
It may look minor now, but you will have no clue whats going on in some more complicated problems if u miss it
same for dx
Points are pretty meaningless - the important thing is the learning process
Yea let's say you ignore +C in something like ln y= x + C
then you get y=A e^x for some constant A which is very very different than y=e^x
Just ran into the fact that mathematicians don't have an agreed upon definition of Natural Numbers in my Discrete Maths homework... oh boy. I want to love maths, but when you have 2 logically and algebraically equivalent equations and one is solvable but the other isn't... now I learn this... sheeeeesh.
isn't it great!
😢
I watched my Calc 2 professor, do some digusting alchemical algebra to the function f(x) = x^x
to transform it to f(x) = e^(xln(x))
Eventually it satisfied the requirements for L'Hopitals rule, that kind of broke me inside.
good 
isnt that pretty standard
it's like building muscle
The more I learn about maths, the more I realise, it is all made up and isn't fully logically consistent.
it is all made up
very philosophical question
isn't fully logically consistent.
wut
No (?)
Though I'm also realising that high level maths actually excites me, unlike algebra. Discrete maths is challenging but actually kind of fun.
There is high level algebra
algebra has many meanings yea
high school algebra is very dry yea
but builds good foundations, and doesn't have to be dry
abstract algebra is beautiful though
and yea discrete math is cool
first introduction to many cool structures in math
and probably your first introduction to proofs?
What is beautiful about it lmao
proofs >> mundane calculations
1st: ouch
2nd: lemme guess you prefer analysis?
3rd: (now I'll be serious) I find the study of these structures to be cool. The theorems are satisfying and certain ideas like exact sequences (which I'm learning about right now) and the parallels between R-modules and categories is fun to study.
groups pop up in many places and some algebraic flavors of other fields (algebraic complexity theory, algebraic number theory, or algebraic combinatorics) provide neat perspectives
I rmb last time I tried Rosen it bored the shit outta me 
Then I have been doing Enderton since 

Implying you haven't seen the good ones yet
What is a good one?
Grothendieck's generalization of the Schwartz kernel theorem comes to mind
Thanks, maybe I need to dive deeper
Algebra proofs are contrived exercises in rewriting
Analysis proofs are explorations of a wildnerness
Algebra proofs are done via definitions, analysis proofs are done via techniques
I'm reading about substitution cipher, and I thought “Can I represent all substitution ciphers as combining chunks of shift ciphers with different keys?”, then try to categorize all base-26 monoalphabet substitution ciphers and found that some of such combinations are not possible, for example the case where the first 13 letters are shifted 0 and the rest 13 letters are shifted 1, doesn't make a proper cipher because A and Z are both mapped to A
algebra proofs can be cool
That sounds less remarkable when I wrote it out
all substitution ciphers can be represented by a 26 degree polynomial in Z/26
well ig it's atmost 25 actually?
I think you can do smaller
So basically I am convinced that no substitution cipher is the combination of exactly two shift ciphers, regardless of the base
Don't know how to prove it formally though
1-x^12 is an indicator for 0 mod 13 and 1-x is an indicator for 0 mod 2, so f(x)=2(1-(x-a)^12) + 13(1-(x-a)) should be an indicator for a mod 26
then do a linear combination of these
The trivial substitution cipher is, though.
by indicator I mean an indicator function 1 at the number, 0 otherwise
The trivial one is shift 0 isn't it
Basically map each element to itself
So it's exactly one shift cipher
This can be represented as the combination of two opposite shifts
No, one substitution is the combination of two shifts
basically since 26 is composite and not prime, the power is lower cause we're not using fermat's little theorem anymore and we're using the chinese remainder theorem to patch our polynomials together
What does indicator mean here?
@split oak
Ah ok missed that
can we get a indicator of degree less than 12 for Z/13
$$f(x) = \sum_{a=0}^{25} f(a) [2^{12}(1-(x-a)^{12}) + 13(1-(x-a)) ]$$
just to try to be clear what I mean specifically, f(a) is just whatever you want it to be
err actually I have a minor issue, I could fix it by raising 2^12 though
Merosity
to have the reduction mod 13 clean
well since the indicator f(x) satisfies that f(x)=0 for x != 0 that means it already has (x-1)(x-2)...(x-p-1) =x^{p-1}-1 as a factor since it's a field
it might be possible that we only need lower powers though to represent certain types of ciphers
yea true
caesar cipher is just x+5
or yeah that one, or idk the names of these things lol
I just guessed shift cipher is the one where you just move the letter a little lol
I wonder how caesar cipher was considered a good cipher in ancient Greece
we have at least phi(26)*26 invertible linear ciphers
Can't anyone who can read just decipher it
lol I guess people couldn't read back then
I guess this is a drop in the bucket compared to the 26! invertible maps that need to be accounted for, we might be able to pigeonhole principle show that we need degree 12 polynomials
yea absolutely
26^13 > 26! I guess
That seems ineffective
Even as late as 1915, the Caesar cipher was in use: the Russian army employed it as a replacement for more complicated ciphers which had proved to be too difficult for their troops to master; German and Austrian cryptanalysts had little difficulty in decrypting their messages
that looks wrong to me
am I counting wrong, there are 26! bijective functions from a set with 26 elements to itself and there are 26^13 degree 12 polynomials with coefficients in Z/26Z
lmao damn
well aren't coefficients constrained to be in a certain way in our solution
If you could read back then and had a lot of experience in combat you could be elegible as a centurion for the roman empire millitary
yeah, but it's an upper bound even when you overcount
It's a very inaccurate one
n^(n/2) < n! for n>2
yeah so what's wrong here
supposedly:
|{degree 12 polynomials mod 26}| > |{bijective functions on set of 26 elements}|
however 26^13 < 26! lol
is there some reason the CRT stuff I said doesn't work, is my life a lie rn lol
I see why this can't work I think
reduction mod 13 will give f(a) and f(a+13)
well that's in the garbage
on the flip side, I know we can find an integer valued polynomial in Q[x] of degree at most 25
Yes I agree
I don't think we can guarantee that it'll have integer coefficients though, which would be equivalent to saying their denominators are not divisible by 2 or 13, since all other denominators d can be cleared by multiplying through by d^12
Is it normal if youtube math videos make me understand the material better
I guess as sorta a heuristic, f(n) = n(n+1)/2 mod 4 represents a bijection on Z/4Z
Yes
try representing this with a polynomial that doesn't have 2 in the denominator
Im not saying im a calc student but there would be no shame is lets say a calc 3 student watches a yt video on a subject
But it seems like every calc student who uses youtube watches the organic chemistry tutor or professor leonard
but I think it's a mature thing to try to get accustomed to other forms of learning as well, since often times you don't have control over the form of the source of the thing you might want to learn
Isnt n(n+1)/2 the partial sum formula for arithmetic series
coincidentally yep
it's also the number of ways to pick two items from a box of n+1 items
I would not learn anything in an online school but being there physically and interacting with teacher is what most likely makes me learn better
yeah that's what I mean about not having control over it
I found a counterexample:
0,1,2,3 maps to 0,3,2,1 with shifts 0,2,0,2
But the structure of n,n,n,…n,x,…x,x,x should still be impossible, as well as n,n+1,n,n+1…
a substitution cipher is really just a permutation yeah?
To be clear what I'm doing is recreational
and S_26 is a group anyway
not sure what "combination" here means
if you mean one composed on top of another
then that's not true because you can just compose the trivial identity permutation on it
No, just concatenations of fragments of different shift ciphers
All permutations can be decomposed as a product of transpositions. Maybe that's what you want?
Sounds like it
Wdym by fragments of ciphers
Like you make your custom cipher as "f(x)=x+5 for x=2 and f(x)= x otherwise"?
Yes
Ok that's exactly this
Everytime I learn something new in mathematics I feel like a kid opening a new box of toys. That's probably a good thing.
So a transposition (a,b) can be represented as "f(x)=x+b-a if x=a and x otherwise"
Now decompose into transpositions and you have your chain of custom ciphers
is this just all permutations can be written as the product of 2-cycles
because yes that's true
Same thing
What is a 2-cycle?
A permutation that fixes everything except for 2 elements
So f(2)=3, f(3)=2 ,f(x) =x for all other x is a 2-cycle
One more useful terminology learned today
Well the 2 comes from there being 2 elements in the cycle notation
This would be (2,3)
or just (23) lmao
you can decompose everything into 2 cycles like
(12345) = (12)(13)(14)(15)
Is this from graph theory?
no group theory
Got it. It reminds me of cycles in graphs, because you map one to another and it would look lile a cycle on a graph
Well, I guess all other elements are mapped to themselves so they're all cycles
oh sorry my decomposition was wrong
But this cycle has two nodes in (on?) it
There's a very simple way to decompose any arbitrary permutation like this
On further examination, in case of n,x,n,x… , only n,n+2,n,n+2… seems to work
Decompose into disjoint cycles. Now let's say a cycle is
(a_1,a_2...a_n). A decomposition is (a_1,a_n)(a_1,a_{n-1})...(a_1,a_3)(a_1,a_2)
[composing permutations right to left]
Simplify the given expression, following which it would be trivial to compute the range
What are the integers that satisfy a, b, and p for the expression
Calm down. Are we going to do all your homework XD
no its not homework XD
Jk
Use the Sophie Germain identity
!help
Please read #❓how-to-get-help
How does this work?
If x+y+z=xyz, then x=tanα,y=tanβ,z=tanγ(α+β+γ=π)
!help
Please read #❓how-to-get-help
Could anyone help me with a math question? It’s in the nunya help channel, I’ve been waiting for quite some time
!help
Please read #❓how-to-get-help
grass for mod 
i sully your sully
blue grass
Blue Shuri 

does anyone have experience applying for NSERC USRA
have you tried RTNSC KRSLAN
?
hes trolling.
its a undergrad student award for canada unis
the girls who get it, get it, the girl who dont, dont.



with all due respect, this is easily googled.
though the fact that you dont understand the acronym also means the question clearly doesnt apply to you
so you coudlve just ignored it
rather than being an asshole
ok
dam illum being schooled
dont belittle them because we were all immature at some point
Speak 4 urself
Unfortunately, I am not Canadian (though I do live almost directly on the border just a couple hours out from Niagara Falls, and there is a Tim Horton's in my town, so it's hard to tell sometimes...). Best of luck with your application though!
what do you think is a good place to find mathematical articles ?
Ask professors for something accessible. Or browse ArXiV and struggle.
what do you think about the articles on arxiv?
"the articles on arxiv" is just, every single paper someone's tried to publish in the past 30 years
tim hortons does not make you canadian (anymore)
every single person i know hates tims
and i live in canada
the place has gotten so bad
what would you do if you keep doubting your proof even though it's right?
Someone posted this on a server I'm on
He also claimed to have solved climate change and world hunger
why are these just a bunch of photos of some drawn stuff
i've seen some very interesting stuff in that queries spot
one time i saw something related to my little pony

@deep mango Sorry to ping but you seem like the right resource to ask, do you know of any fluid simulators that are "simple"?
Simple to use rather, and free for students
i do not, sorry
I'm having trouble visualizing the velocity field created by a rotating body
i dont know anything about fluid numerics yet
Would you mind checking my thinking for a conceptual problem then?
(The one I'm trying to model)
maybe in a bit, but im busy rn
No problem, take your time. Mind if I DM you it?
Oh shit never mind I found a YouTube video on it 💀
Thank you for responding though!

There's this one person in our grade that has a sister who did BC calculus in 7th grade
It's completely insane
You can find quite many resources if you have matlab (your university might have free subscription) and search for related matlab scripts. An example is this: https://www.youtube.com/watch?v=lbTTGiM6zJQ (it gives a link for the script in the description).
Yep, I get free MATLAB
But I want to try and derive it myself/see an explanation for the derivation
I'm trying to find the velocity field generated by a right cone rotating in a fluid
Having trouble visualizing it in my head
What's the usual undergrad math progression? I assume something like Calc, linear algebra, real analysis, diff eqs, complex analysis?
(In order that the average math major would take)
Real analysis almost always goes before complex
Calculus would usually go before real analysis (or there won't be a "calculus" course at all)
Linear algebra would go early up but doesn't have much to do with analysis, proof-based linear algebra can often go a bit later depending on the program
Differential equations seems to be optional at most places, but at places where it is mandatory, it will usually go after calculus (and possibly linear algebra)
Thanks!
hey, i wanna learn math like from scratch
where should i start?
We talking arithmetics like plus, minus and stuff?
probably start with khanacademy
I can be taking you mathematics
no no haha, I'm an undergrad second year of college
something a bit more than that i guess
you teach meth?
percentages? Ratios and rates?
no
more than tha
I know calc, algebra, combinatorics, prob, stat
and some other stuff
but still I want to start everything from the basic
yk
Khan academy
hmm thanks
Hi hi
Yes
where would number theory fall in that progression?
Hmm, one would generally pick up some elementary number theory as a part of abstract algebra classes, but number theory classes in themselves are largely optional from what I know
It's a more specialised domain in a way, although elementary number theory classes are often used as a springboard to proof based mathematics
seriously though.
why/when/where do we use it
$$\sum_{n=0}^{\infty}\frac{f^{(n)}(a)}{n!}(x-a)^n$$ according to ahh. Wikipedia. I am reading about it
The W
It's a way to approximate a function using polynomials (which might be way more easily studied)
👍
It's conceptually very intuitive and in some cases, letting the sum go to infinity would approximate the function perfectly
A good way of thinking about it is it's a stronger theorem than the mean value theorem
(indeed, for n=1, the two theorems coincide)
This isn't Taylor's theorem that I'm talking about btw, the sum can go to infinity only if the function is infinitely differentiable
there are infinitely differentiable functions that do not have a taylor series expansion tho
C^infinity and analiticity are different concepts
I see 
I was just trying to hint at the fact this sum might not even make sense for all functions
I answered the why
But when and where I can only say "in analysis"
More specifically perhaps "real and complex analysis"
"in math"
does mvt imply ivt
No
mvt applies when the function is differentiable on an interval
Since ivt is for all continuous functions and not all continuous functions are differentiable, the mvt can't possibly imply ivt
(without mentioning the fact that there exists continuous everywhere, differentiable no where functions
)
ah yes that one fourier series
the set of differentiable everywhere functions is meagre in the set of continuous functions
painful
connected spaces and locally path connected spaces
whats possible research topic related to magic squares?
I think combinatorial design is a related field to look into
thank you im having a hard time deciding wether to choose magic squares or schur triple theorem
Choosing for?
undergraduate mathematical research
Ah, okay
Both sound interesting, I have been recently reading about BIBDs as a part of a class
They're also very cool
whats BIBDs?
yea and im kinda stuck rn
so true
Balanced incomplete block designs, they are "combinatorial structures", like graphs/magic squares, etc.
Just like for magic squares you have a collection of objects (generally numbers) and some constraints on how you want to arrange those numbers, block designs are concerned with building families of subsets of a given set
That satisfy certain constraints (how many subsets should each element appear in/how many subsets should every pair of elements appear together in/how many elements should be contained in each subsets)
Then the problem generally is about determining if for a given value of these parameters, a corresponding family of subsets exists or not
And if it does, how one would go about constructing it
I haven't learnt a lot about it, but this is the broad theme from what I've picked up
Might help to discuss this with a thesis advisor or someone working in a related area at your institute, imo
currently searching it up, looks interesting
i wish i can do that, we have to come up with a topic proposal first before we get to talk to any advisor
Ah ooof
Hold on there's a better way to write this
Would it be possible to reach out to potential advisors beforehand?
$$e^{\frac{d}{dx}}f(x)$$
nHail
Then you expand that as a power series
inside my institute its not possible
Well, I guess you really have to make a call then
See what you find most interesting
To me it seems all of these are pretty interesting ideas for an undergrad thesis
You can ask for more opinions in #combinatorial-structures since that seems to be your primary interest area
thank you so much, are u still a student?
Yeah
cool whats your course if u dont mind
ohh same what year?
3rd and the last
cool, ig you’re having fun taking the course
Yeah, it's an interesting class so far
BIBDs will not be taking up a large part of it though
After BIBDs it will move on to some coding theory
Followed by some random assortment of topics
Mostly about special matrices and groups with a view towards applications
is conducting mathematical research also one of the requirements finishing the course? if yes do u have any ideas that you’re interested in doing
manan coding theory arc?
I know this will sound a bit crazy but please entertain the idea for a second. It looks like I have a polynomial-time algorithm for listing all maximal cliques of a undirected graph, which constitutes a constructive proof for P = NP. I'm almost certainly wrong for reasons I cannot yet see, I'm sure many people have thought they've had something before. What would you say is a good approach for getting peer review? You can't just publish something like that. On the off-chance that it's not mumbo-jumbo, it would have severe implications on cryptography, etc. Just entertain the idea for me and I'll eventually find the error or be proven wrong by peers.
And nevermind my nickname, I know it's ironic given what I'm saying but I actually want a serious discussion.
The problem is an NP-complete one, as you probably know.
So far, I have been unable to find bad outputs but testing continues.
lol maybe
you get it peer reviewed by just talk to a professor
or your boss
are you in a STEM position professionally? or a student?
a professor or boss you trust
by this I just mean so you can say it lazily without revealing anything for us to scoop u 🍨
I had two professors to tell me not to tell anybody else some ideas they liked
I think that's a good confirmation
one literally said "don't give that one away"
meh I don't think there's much point in secrecy around ideas most of the time
yeah most of the time
lol
when you're having your once in a lifetime flash of brilliance I dunno
but the only way you can know it is that is by sharing it with trusted peers
you cannot be objective
make a youtube video explaining it, post it to multiple social media sites so that it's time stamped, and then you have proof you thought of it first if someone publishes after the fact
yeah how do you wanna capitalize? my end-run was get a biotech incubator going on, but due to disease I missed it
like just go apply. There are people who will take 5% but give you a million dollars
I agree with merosity but not about the youtube video
send yourself and trusted associates documentary evidence
or just yourself, I don't think multiplicity is necessary
the sad truth is there might be somebody out there who thought the same thing but they don't know it's important yet
they see your youtube video with 1 mil views
only one? you need to have an abundance mindset 😎
they then officiate before you do
I'd scam the patent off a dog
yeah, I probably should. It freaks me out though, I've had wiser superiors be like seriously guard that.
in fact, I do
I'm like whatever man everybody has done everything 5 million years ago
a dinosaur expressed that patent with a dance
I got my last job simply by scaring my employer
by like knowing exactly what he wanted to do
I think you should force anybody else who has the idea to join your company
Wait I'm confusion
So an observer in an inertial frame of reference sees an objecte moving in a rotating frame of reference due to the Coriolis force right
Oh I think I'm misinterpreting the image?
If you're on the red ball, the black ball looks like it's going straight
BUt if you're outside of that system you can see it's clearly moving in a curved pattern
yeah
wait what
super wrong
if you're looking from outside the rotating frame of reference, it looks like it's going straight
I wouldn't use words so much for that one, I'd just think about it.
Oh
What's the path it's actually moving on? Or does that depend on your perspective?
Like is it going in a straight line or curved? But depending on where you are you see it differently
I think the whole point is the effect is about the perceived path
usually demonstrated with an objectively straight path
and a changing frame of reference
there is a singular, actual path. Don't be confused by that. It's just that to define that path requires a frame of reference.
it's one of those mind blowers like wait we define words with other words? where does it end? and the endpoint is the same: you make something arbitrary up
then you agree to stick to it during reasoning, because consistency within the system is all you need, you don't actually require an objective frame for anything
this clearly implies God
This is a great way to put it
but not this?
Software engineer. Obviously some background in CS.
There would be that about shining, sure, entertaining the thought. But how would you ethically even announce it?
You can't just say "Hey, banks, I'm publishing something in one year, trust me. You must change all of your security."
I do not believe in God, no
Again, we are just entertaining this fantasy.
You are welcome to your opinion though
change it to what?
I think the actual end result of your proof would be the total collapse of security forever
I'm just saying show your boss and peers
if you don't have people you respect who respect you, then make those people
Well, there are ways around it --- not all ciphers are based on the assumption that P!=NP.
which are those?
if you're talking one time keys etc it's fine
but if you're talking algorithmic hashes of the type that afaik comprise all modern security protocols, what?
The most obvious one would be the OTP, which secure stream ciphers are trying to immitate in a more convenient way. But there are others as well.
It is.
like you said otp
just a heads up that's what I meant
THIS MAN'S A GENIUS
and yeah man that'd be the one
we'd literally be one time key forever
I'd appreciate that, I think
bigass kkeys
nah not even that big, collisions would be practically never
I believe there are a few alternatives but I have not looked into it. My background is not in crypto even if I'm not completely oblivious to it.
People usually say "most cipherps would be broken" but I have not looked into it further.
not-obliviously solving a problem i myself am satisfied is insoluble
I expect it probably is. I do not have any confidence in this result as of yet.
I have decent reasoning
that what you think you have is not that
on the basis of the actual problem
But I have to puruse it nonetheless for the time being even if to disprove it.
man who doesn't?
I wrote a shitty compression algorithm as an undergrad that I was certain would revolutionize
I think you are brave and honestly quite bright simply for taking the tact which you are
i.e. find a counter-example
you think it works, and the most reasonable response isn't "this is now a premise"
it's try to kill it
honestly and genuinely
I mean I don't want to be delusional. 🙂
some people super do!
but yeah. Just hang onto it until you've got someone you trust who can work through it with you.
I sought out those people.
Even so --- suppose despite all odds there's something there. What would even be a normal step into publishing this? Can't just publish it and wait for some terrible consequences.
bro publishing is not something you do before peer review
and you do not generally peer review before doing your actual serious peer review, which is like colleague / inner group review
and I agree, ethics
Well, no. But suppose my colleagues would agree and it would be time for peer review. That means publishing. While everyone's figuring stuff out, some evil programmer somewhere uses it. Or some government. Or whatever.
I'm not saying this is the real world. But in this pretend world.
Probably not 🙂
At any rate, if someone had something, they couldn't just put it up on arXiv or whatever.
some people would abandon the pursuit entirely and never bother to confirm or deny their hypothesis
Because the very next day, something bad would probably happen.
I think ethically it's dicy, because if it's out there, somebody else might crack it
who? who knows. Perhaps an ultra-orthodox terrorist
perhaps an insane child prodigy
On the other hand, the person who had this shouldn't NOT publish it either since apparently protein folding is NP-complete and is an important component in developing a cure for cancer.
So it's a weird situation to be in for this hypothetical person.
things would just be different. I have no idea what would happen if somebody declared security over.
immediately subsaharan africans would have nuclear fission etc
All economy and national security revolves around it.


