/sqt/ /qtddtot/ - stupid questions thread

[Anonymous No.14536214]

Previous thread: >>14515149

>what is /sqt/ for?
Questions regarding math and science. Also homework.
>where do I go for advice?
>>>/sci/scg or >>>/adv/
>where do I go for other questions and requests?
>>>/wsr/ >>>/g/sqt >>>/diy/sqt etc.
>how do I post math symbols (Latex)?
rentry.org/sci-latex-v1
>a plain google search didn't return anything, is there anything else I should try before asking the question here?
scholar.google.com
>where can I look up if the question has already been asked here?
archived.moe/sci
>how do I optimize an image losslessly?
trimage.org
pnggauntlet.com

>where can I get:
>books?
libgen.rs
z-lib.org
stitz-zeager.com
openstax.org
>articles?
sci-hub.st
>book recs?
sites.google.com/site/scienceandmathguide
4chan-science.fandom.com/wiki//sci/_Wiki
math.ucr.edu/home/baez/physics/Administrivia/booklist.html
>charts?
imgur.com/a/pHfMGwE
imgur.com/a/ZZDVNk1
>tables, properties and material selection?
www.engineeringtoolbox.com
www.matweb.com

Tips for asking questions here:
>attach an image (animal images are ideal. Grab them from >>>/an/)
>avoid replying to yourself
>ask anonymously
>recheck the Latex before posting
>ignore shitpost replies
>avoid getting into arguments
>do not tell us where is it you came from
>do not mention how [other place] didn't answer your question so you're reposting it here
>if you need to ask for clarification fifteen times in a row, try to make the sequence easy to read through
>I'm not reading your handwriting
>I'm not flipping that sideways picture
>I'm not google translating your spanish
>don't ask to ask
>don't ask for a hint if you want a solution
>xyproblem.info

[Anonymous No.14536317]

riddle me this. if i want to eat an apple everyday and i procure an apple once a week then how many apples must have at the start to keep eating an apple a day?

[Anonymous No.14536327]

>>14536317
You have not specified the given time period

Your equation reads like this

1/7x-x+original apples = days

[Anonymous No.14536335]

How the hell can I get some SU-8 (or any high aspect photoresist)? I don't have sigma access and don't want to shell out hundreds or thousands of dollars to buy the stuff in absurd quantities.

[Anonymous No.14536969]

What would happen to me if I got hit by a neutrino

[Anonymous No.14537108]

What does Nα mean there?

[Anonymous No.14537112]

>>14537108
Not achieved, I think.

[Anonymous No.14537116]

>>14536214
What field of computer science/IT do I need to go into if I want to work on stuff like content moderation and combating hate speech and disinformation on social media platforms? Would that be considered like cyber security or something else?

[Anonymous No.14537156]

Please explain the 'max a' in the Bellman Equation.
What is the value of the action? How can an action be a maximum? I can see a state and a reward having a choice that would definately have a maximum. I don't understand action here. An action is just up, down, left right in a simple game. I would think would be [0,1,2,3]. To take the max of the possible actions would be to go down every time? That can't be right.
What numerical value is the max a?

[Anonymous No.14537166]

Is there any quick way to get some kind of confidence interval or other similar thing if the only thing I know is what percent of the population I'm sampling from? Basically, if I take X out of Y things from a list and on average I enjoy them Z amount, what percent of Y would X need to be for me to get a decent estimate of my enjoyment of the whole thing?

[Anonymous No.14537173]

>>14537116
I'd recommend abnormal psychology with a specialization in gender dysphoria

[Anonymous No.14537178]

>>14537112
i always thought it was "not applicable"

[Anonymous No.14537184]

From calculus 4th edition by spivak.
How the FUCK do I solve this using the properties he has provided me?

[Anonymous No.14537191]

>>14537178
It is not applicable 99% of the time.
I just think it's not achieved this once.

[Anonymous No.14537215]

>>14536214
Is there consensus on the safety profile of novavax and are there any sperg blog or youtube channels following novavax apart from the obvious? What about myocarditis in particular? Are there any studies on all-cause mortality?

[Anonymous No.14537219]

What is the summation here in the Bellman Equation? What exactly is being summed up?
What good does it do to sum up all the next states? I would have thought you would just take the next state with the maximum value. Why are we adding things together?

[Anonymous No.14537243]

How to get this:
[math]<\vec{E}^2>=\frac{P}{\sigma V}[/math]
starting from basic electromagnetism formulas?
< > is a time average, E is electric field, P is power, sigma is conductivity and V is volume

[Anonymous No.14537247]

>>14537184
Bring the two on the left hand side, then find the roots of the parabola. Draw it to understand it better

[Anonymous No.14537317]

>>14536214
If you see a statement "All cats are dogs"
Px "x is a cat"
Qx "x is a dog"
Is this Vx(Px->Qx)?

and then if you add "Bobo is a cat"

Does that mean Bobo is also a dog?

[Anonymous No.14537320]

>>14537317
Sorry only the statement "all cats are dogs"
without defining Px and Qx (i defined them after)

[Anonymous No.14537514]

Failed my math exam today lads, it hurts. Out of 12 possible choices, I got the worst one, namely "Equations and System of linear equations".

Is there any way I can easily read up on algebra?
Recursive and Explicit formulas are heavily focused on, but general knowledge is appreciated.

[Anonymous No.14537530]

Is there a limit to how fast an object can rotate? Sometimes I perform a thought experiment where a spinning disk gets faster and faster. And there comes a point where it feels like it can't spin any faster because its own centrifugal force begins to work against it.

Is this real or is my internal simulation wrong?

[Anonymous No.14537552]

Is it a crime to write the chain rule like this ?

[math]\partial_t f = \partial_x f\; \partial_t x[/math]

[Anonymous No.14537561]

My homework problem is to find all continuous functions f:(0,inf) such that f(xy) = f(y) + f(x) x,y are real. Could someone help me with my solution?

I started by taking x=1 -> f(1)=0 then x = y -> f(y^2) = 2f(y) and f(y^1) = 1*f(y) is trivial.

Then using induction hypothesis f(y^n) = nf(y)

you take x = y^n and thus f(y^(n+1)) = f(y^n) + f(y) = nf(y) + f(y) = (n+1)f(y) and from there it's easy to see that f is the logarithm. And since log b (a) = ln(a) / ln(b) the final answer is C * ln(xy). But I don't think that using induction for only integers is enough of an argument to show that the function is indeed c*ln(xy). what am I missing?

[Anonymous No.14537587]

>>14537561
You want to show that [math]f(x^q) = qf(x)[/math] whenever [math]q[/math] is rational and then extend to real [math]f(x^y) = y f(x)[/math] by continuity.

[Anonymous No.14538000]

so this is a dumb question but I would like clarification. Also I can't into Latex because I am dumb so I will use U for union and n for intersect. so P(M)=probability of owning microwave, P(C)= Probability of owning CD player. So P(M)=.75, P(C)=.25, P(MnC)=.16, the problem is asking for probability they have microwave or CD, but not both so I do P(M)+P(C)-2*P(MnC). My professor is telling me not to use the 2, but we are not considering the P(MnC) so we need to subtract off two of it. He told me "or" has to mean one or the other but I told him in the formula we have been given P(AUB)=P(A)+P(B)-P(AnB), the AUB is not an exclusive or, to which he told me he had never heard of exclusive or in his life. Am I wrong in including the 2? I feel like the fact that they are asking for not owning both means we need to subtract P(MnC) twice.

[Anonymous No.14538287]

What is a woman?

[Anonymous No.14538458]

>>14537530
The centripetal/centrifugal force is radial, so it doesn’t matter as far as inhibiting further rotation. Relativistically no point on the disk can go faster than light, so eventually weird stuff happens, but that isn’t the sort of thing you’d have an intuition about

[Anonymous No.14538480]

How do electric fences work? Trying to look it up I just get a bunch of fence companies giving the BS “back to the source” explanation of electricity. I know some use multiple lines with inverse polarities (like netting systems) but I’m talking about the most basic ones where just one line shocks you. My guess is it’s the same as a rubber shoes on carpet situation, as in the fence causes you to build up voltage, and the shock is a discharge to ground. Would that be correct?

[Anonymous No.14538571]

>>14537530
If you're trying to say that there's a limit to how fast real objects can spin before the centripetal force starts deforming them instead then that sounds correct but I don't really know anything about deformations.

[Anonymous No.14538592]

why are torques and curls perpendicular to the direction of their motions
I can understand the magnitude, but if you have a disc that only spins in, say, the x-y plane, why the fuck does the Z axis have anything to do with it

is there any physical reason or is it "just how the math works out"

[Anonymous No.14538635]

>>14538480
Capacitative coupling

[Anonymous No.14538645]

>>14538592
Rotations are technically two-forms but it took a while for differential forms to be invented so physicists have basically always used a hack to turn two-forms into vectors.

[Anonymous No.14538674]

>>14538000
You definitely should be subtracting twice P(M∩C).

P(A∪B)=P(A)+P(B)-P(A∩B) is the inclusion-exclusion principle. But as you note, you don't want P(A∪B) you want P(A∪B)-P(A∩B).

[Anonymous No.14538676]

help?

[Anonymous No.14538678]

>>14538635
Can you explain further? I’m not getting how that would work given the pulse nature and strength of shock.

[Anonymous No.14538754]

>>14538676
1. "A" is the result of ozonolysis (to aldehydes) followed by big fuckin oxidation (to carboxylic acids). "B" is the result of esterification. "C" is the result of reduction (with only 1 eq of DIBAL, it will reduce it only once to an aldehyde).

I'll let someone help with 2

[Anonymous No.14538772]

Is geometric algebra worth learning?

[Anonymous No.14538777]

When I was a kid I always wondered how they calculated fuel efficiency rates for cars if the car burns fuel when it's not moving.

[eqn] \dot V = \frac {\partial V} {\partial t} + \vec \nabla V \cdot \vec v [/eqn]
(Right?) So we can rearrange and assume 1-D travel to get
[eqn]\frac {\partial V} {\partial x} = \frac {\dot V - \dot V_\mathrm{idle}} {v} [/eqn]

Is that how it's done? Or is it more based on measuring spent fuel (beyond what would be spent idling for that time?) and dividing it by the distance traveled?

[Anonymous No.14538785]

>>14538777
Textbook rec for if I want to understand your question?

[Anonymous No.14538841]

>>14537243
Hint: use Ohm's law and the formula for Joule heating

[Anonymous No.14538882]

>>14537530
https://youtu.be/n-DTjpde9-0?t=191

[Anonymous No.14538994]

I just wanted to give my belated thanks to the anon who helped me with my limit at infinity proof question in the last thread. Turned out I just hadn't learned about the epsilon delta definition yet, duh. Got full marks on my exam by the way.

[Anonymous No.14539000]

>>14536214
For x= y/2, why can't I just plug 6 into y to get x=3, and then solve for the derivative that way?

[Anonymous No.14539067]

SO(N) can be realized by constructing the spin group Spin(N) out of a real Clifford algebra over [math]\mathbb{R}^N[/math]. Is there an equivalent construction for SU(N), by constructing a "complex" spin group out of a complex Clifford algebra over [math]\mathbb{C}^N[/math]?

[Anonymous No.14539100]

Does anybody have a book recommendation for turbulent convection, i.e. rayleigh benard convection and kolmogorov turbulence shit?

[Anonymous No.14539312]

>>14538678
It's a pulse. It doesn't have to maintain a continuous flow of current, it just needs to move some charge in and out of whatever touches it. Any conductor has a self-capacitance proportional to its size (for a sphere, C=4πε_0R; for a person, this comes out to a couple of hundred pF), and you'll also have some mutual capacitance with the ground.

[Anonymous No.14539318]

>>14538777
Fuel efficiency is measured either at constant speed or over a standardised test cycle (for "urban cycle" consumption). The latter will take account of idle consumption, although it isn't a particularly significant factor; repeated acceleration from stationary accounts for most of the difference between urban cycle and constant speed consumption.

[Anonymous No.14539475]

say I'm storing an array of integers somewhere, can data corruption affect the array's element's indices (for example changing an index into another by changing some bits) or just their values?

[Anonymous No.14539625]

>>14539067
Far as I know, no.

A Clifford algebra is constructed from a vector space equipped with a quadratic form, and U(n) is constructed from a vector space equipped with an inner product.
In the real case, inner products and quadratic forms are the same thing. In the complex case this doesn't work because of sesquilinearity.
So you can have some incidental isomorphisms but you wouldn't expect there to be a canonical construction going from one to the other unless you could canonically associate an inner product to a quadratic form, which isn't really a thing either.
>>14538772
Yeah.

[Anonymous No.14539805]

I inflicted a razor cutting wound on the tip of my index finger and while I did wear band aids most of the time on the third day I didn’t wear one even though the wound was still kind of open. In case debris got in the wound, does the body have any kind of mechanism to decompose it and if not can this have long term impact on my health apart from me having to deal with the fact that there’s stuff stuck under my skin. I have OCD, please bear with me.

[Anonymous No.14539809]

Guys, I've been studying HS math and now I got stuck on these problems, don't mind the Portuguese, it's just asking for a demonstration of those expressions. How do I even begin to do it? The only way I could prove it was by squaring both sides and going from there, but it's no really sophisticated. Should I even be worrying about proofs at this stage?

[Anonymous No.14539823]

>>14539805
>In case debris got in the wound
as the wound closes it would be pushed outside by the new tissues and you wouldn't even notice

[Anonymous No.14539837]

>>14539809
As duas ultimas questões são basicamente aplicando a letra a da primeira. Tente resolver elas manipulando a letra a. A primeira questão tu pode basicamente usar todos os casos possíveis(x,y > 0, etc) ou lembrar que x <= |x| para todo x.

[Anonymous No.14539842]

>>14539809
>>14539837
Acabei de ver que é negativo na letra a. Então use |x+y| <= |x| + |y|. De fato, tu pode usar isso pra resolver todas elas.

[Anonymous No.14539850]

I know chess engines are significantly better than humans at this point.

Is it possible for a common laptop or PC to be able to train a neural network from scratch that would be better than humans?
Or is that level of hardware just considered unreasonable and supercomputers are needed?

In other words...
Can I train my own AI on my own hardware (assuming I have average hardware) to be better than most humans or all humans?

[Anonymous No.14539851]

>>14539823
cool thanks

[Anonymous No.14539854]

>>14539850
If you can afford to wait for 1000 years, maybe.

[Anonymous No.14539858]

>>14539850
Unlikely. NNs would be very good for statically evaluating a position, but not for recursively drilling down and meticulously calculating the possibilities.

[Anonymous No.14539860]

>>14539837
>>14539842
Acredito que eu tenha conseguido resolver satisfatoriamente todas da primeira questão, a), b) e c)., em todas as demonstrações eu elevei ambos os lados ao quadrado até chegar na expressão do tipo a<=|a|, que é obviamente verdadeira, é uma resposta aceitável?
Na 4.8, a segunda questão, não consegui traduzir muito bem para matemática, apenas generalizei em dois casos:
1. Todos os números x,y,z são positivos ou negativos, nesse caso, |x+y+z| = |x| +y| +|z|
2. Úm dos números é negativo, assim, |x+y+z| < |x| +|y| +|z|
E fiquei por ai mesmo. Novamente, é uma resposta aceitável?
A 4.81, a última, não conseguir concluir, só cheguei até |x-a| + |y-b| < 2k, não consigo prosseguir.

[Anonymous No.14540015]

>>14538841
Got it, thank you

[Anonymous No.14540056]

I've been fascinated with astronomy ever since I was little. Sadly, I'm too stupid to get into school focused on it, plus I already have my path set for my future. How could I pick it up in a more formal way? Not just watching videos about it, reading articles and such.

[Anonymous No.14540438]

>>14539860
>em todas as demonstrações eu elevei ambos os lados ao quadrado até chegar na expressão do tipo a<=|a|, que é obviamente verdadeira, é uma resposta aceitável?
Not really.
>Novamente, é uma resposta aceitável?
Yeah.
>A 4.81, a última, não conseguir concluir, só cheguei até |x-a| + |y-b| < 2k, não consigo prosseguir.
There's a typo on that one.
[math]|(x + y) - (a + b)| < 2k[/math]

Also, post in English unless you want to drastically reduce the number of people who can help you.

[Anonymous No.14540473]

>>14540438
First time I posted it was in English, but the anon who replied did so in Portuguese, so I kept going in Portuguese.
>Not really.
Why not? Iezzi uses a very similar approach to demonstrate the triangle inequality, pic related.
>Yeah.
Well, at least I got one right.
>There's a typo on that one.
It wasn't a typo, I'm not sure if they're equivalent, [math]|x-a| + |y-b| = |(x+y)−(a+b)|<2k [/math] ? Are they? If so, why? I can't quite picture it.

[Anonymous No.14540629]

>>14540473
>Why not?
[math]a = b \implies 1 = 1[/math] doesn't imply [math]a = b[/math].
>It wasn't a typo
I meant a typo on the textbook. You were trying to prove a false result.

[Anonymous No.14540750]

>>14539475
Meaning swap, say, the sixth and seventh entries of the array? The answer will obviously depend somewhat on your data storage, but generally no. Arrays are usually stored as data starting at some base memory address and then moving sequentially upward or downward in memory address in steps of whatever your data type happens to be. When you access the 6th element of the array, the program starts at the base address, adds 6 steps of the data type size, and then looks at whatever is in that spot. So data corruption can’t flip the indices (unless your program itself was corrupted so that the program is attempting to access the 7th instead of the 6th entry, but the data structure itself would be uncorrupted.) Even if the base address were corrupted, that would be an increment of the whole structure, so it would change everything, not just flip two elements.

[Anonymous No.14540778]

>>14539809
Why is this illegal? I don't understand, the conclusion is indeed right:
Case 1: xy > 0, then |xy| > -xy,
Case 2: xy <=0, then |xy| = -xy
[math]|x-y| <= |x| +|y|[/math]
[math]|x-y|^2 <=(|x|+|y|)^2[/math]
[math]x^2-2xy+y^2<=|x|^2+2|xy|+|y|^2[/math]
[math]-xy<=|xy|[/math]

>I meant a typo on the textbook. You were trying to prove a false result.
Shit, this book is indeed known for its incorrect answer key. But where exactly is the typo?
Sorry for replying with everything with a "why" like a little kid, I'm just really ignorant.

[Anonymous No.14540854]

>>14540778
>>14540629

[Anonymous No.14540973]

> A real number is any number that can be represented as a continued fraction.
What do you guys think? Is that a good definition?

[Anonymous No.14541003]

What is the property of a function or operation that it has only one solution? like a+b=c and only c.

[Anonymous No.14541005]

>>14540973
Somewhat, but make a thread for it. I tend to minimize generals like these, and you'll need proper arguments to really get an actual answer on that.

[Anonymous No.14541040]

Finished my masters degree with a thesis at my university and I'm preparing my application files. Is there any advantage to publishing my thesis to, let's say zenodo and attach the DOI to my cv? (eurofag here).

[Anonymous No.14541066]

>>14540973
Rational numbers admit two continued fraction reps so it doesn't work as is.

[Anonymous No.14541135]

>>14540778
Because it's trivial.
Any statement implies [math]1 = 1[/math]. Proving that a statement implies [math]1 = 1[/math] isn't proving anything.
Your proof needs to work backwards. It's not immediate that a proof that involves squaring both sides works backwards.
>Shit, this book is indeed known for its incorrect answer key. But where exactly is the typo?
The book says [math]|(x + y) - (a - b)| < 2k[/math]. The correct statement is [math]|(x + y) - (a + b)| < 2k[/math].
The first statement is false, since we can choose [math]x = a = 0[/math], [math]y = b = 5[/math] and [math]k = 1[/math].
Clearly [math]|(0 + 5) - (0 - 5)| = 10 \nless 2[/math]

[Anonymous No.14541152]

What exactly is the application of a rational expression ? Take a cuadratic equation. Then, the division of one such equation by another is just a curve being 'distributed' by the value of another curve. It is a ratio expressing how many times greater the other curve is. What is another aspect of a rational expression ? A square dividing another if it is a perfect square. Then ? What is a concrete application ?

[Anonymous No.14541156]

>>14541066
How exactly does that contradict his definition?

[Anonymous No.14541177]

>>14541156
The immediate issue with his definition is that it's circular: "real numbers are real numbers that can be represented as continued fractions".
The second issue is the one that shows up if you reduce the definition to "real numbers are continued fractions", which I pointed out earlier.

[Anonymous No.14541191]

>>14541135
So I should start with this proven statement
[math]−xy<=|xy[/math]
And work my way up to
[math]|x−y|<=|x|+|y|[/math]
by applying the properties of inequalities and absolute value?

[Anonymous No.14541221]

>>14541191
Yeah.
You can also work from [math]|x + z| \leq |x| + |z|[/math] and do the substitution [math]z = -y[/math].
The above trick is applicable to a, b and c, actually, with varying complexity.

[Anonymous No.14541240]

>>14541221
Thank you very much, buddy.
Your teachings finally made the subject clear, I was stuck in this chapter for the last couple of days, feeling like a really stupid clown. Also, thanks for your patience, we've been here since 9am.

[Anonymous No.14541303]

Would it be possible to teach myself math? I’m in a community college right now and pretty math illiterate outside of basic algebra. I’ve recently developed a strong interest in chemistry and would like to learn a lot more about it at my current level. Would it be possible for a brainlet like me to be able to learn this stuff or am I too far gone? (23 for reference)

P.S What would be some good books for me to work with if I were to start self teaching?

[Anonymous No.14541311]

>>14541303
Sorry I fucked up the formatting here.

I would like to learn more about it but I don’t think I can at my current level *

[Anonymous No.14541325]

>>14537552
why the partial sign?

[Anonymous No.14541334]

>>14536327
yeah what a retard, days aren't even a number. Neither is apples for tha tmatter.

[Anonymous No.14541571]

https://www.reddit.com/r/suicidebywords/comments/v431ll/suicide_by_highlighter/

why are so many in the comments complaining that it doesn't fit the subreddit? don't they understand the pic? the writer is complaining about the use of 'they' to refer to a singular person but uses it themselves in that way. it seems to fit rule 1 of the subreddit.
>Make sure your post contains a self-deprecating joke/insult, a wrong statement or is otherwise extremely disliked. You are mostly free to post anything just keep the rules in mind when you do.

[Anonymous No.14541576]

>>14539000
Any takers?

[Anonymous No.14541590]

sure if the gender is known then you want to say him/her but the pic is good enough as a mildly funny "gotcha"?

[Anonymous No.14541610]

there's a lot worse offenders that i see regularly like the link below where they act like the republicans want to diddle little girls but they clearly just want a doctor's note confirming the gender

https://www.reddit.com/r/facepalm/comments/v3upgr/ohio_republicans_pass_a_bill_to_stop_the_child/

[Anonymous No.14541611]

if AI became sentient, is the information we are able to provide it with enough for it to think like a human being does? If AI learns through the internet by what humans think say and do, would there be a point where it has gathered enough information for it to recreate a human being accurately in its thoughts and behavior? if AI became conscious, would it think in the same way a human does? AI has a pretty much infinite source of information to learn about through the internet, even if it doesn't exist physically, would it be able to accurately operate in more or less the same way a human does?

[Anonymous No.14541620]

>>14539000
Because you can't implicitly differentiate and get a [math]\dfrac{dy}{dt}[/math] out if you do that.

[Anonymous No.14541658]

it triggers me when my assignment question receives half points and the TA just puts a bunch of question marks for the feedback. SO HELPFUL

[Anonymous No.14541669]

What is the formula for outer product of three vectors?

[Anonymous No.14541758]

i want to learn(maybe master if possible) linear algebra and differential equations in a year, recommend me some books or course, since i don't have a lot of free time i will be able to give it only less than hour every day

i got an introduction to both of them in first semester of uni but i want to learn it properly from scratch

[Anonymous No.14541874]

>>14541758
You'll never master them in your lifetime. There's a million textbooks recommended in the sticky. Watch professor leonard on youtube for ODE hand-holding course.

[Anonymous No.14541880]

>>14541874
well not master in the literal sense, just enough i could do high-end physics

[Anonymous No.14541887]

>>14541880
Judging by the quality of your questions, it'll take you over 10 years to get past undergrad level indepedently. What are you trying to accomplish? A first year physics course uses "differential equations" and "linear algebra" to study simple harmonic motion in the first week of class.

[Anonymous No.14541890]

>>14539850
You can use google colab (for free) to train NNs on googles cloud servers

[Anonymous No.14541892]

>>14541887
>quality of your questions
fuck off

>What are you trying to accomplish?
get good at said subjects

>and "linear algebra" to study simple harmonic motion i
ah yes of course

[Anonymous No.14541895]

>>14541892
good luck with your studies anon

[Anonymous No.14541900]

>>14541895
k

[Anonymous No.14541975]

Given the Euclidean vector space [math]\mathbb{R}^n[/math], what is the probablility than [math]n[/math] randomly chosen vectors are all linearly independent and will from a complete basis for the whole space?

Intuitively I'd think it would be almost surely a basis if you're randomly picking from [math]\mathbb{R}^n[/math], but is there a way to formally quantify the "size" of the space where 2 or more vectors are dependent?

[Anonymous No.14541989]

are atomic nuclei technically black holes? does their mass per radius fall under the schwarzchild or w/e criteria?

[Anonymous No.14541992]

>>14541325
I don't remember the last time I saw a non partial derivative

[Anonymous No.14542025]

>>14541975
Choosing n vectors from R^n is equivalent to choosing an n x n matrix with real coefficients. So you are asking about the "size" of the general linear group GL(n,R) of invertible matrices compared to all matrices R^{n^2}.

Since R^{n^2} is non-compact you need some more precise way of specifying what you mean by "randomly chosen," but it is true that GL(n,R) is a dense set in R^{n^2}. Also if a matrix is not in GL(n,R) that means at least one of its eigenvalues is *exactly* zero. If you have a definition of "randomly chosen" then you can calculate the joint eigenvalue distribution R^n and no doubt getting an eigenvalue of exactly zero would be measure zero.

[Anonymous No.14542050]

>>14542025

Good shit, that's surprisingly comprehensive, thank you.

[Anonymous No.14542051]

>>14541989
No. The radius of something like a nucleon is on the same order of magnitude as its Compton wavelength, which means the inverse of its mass in natural units (and the radius of nucleus is necessarily bigger than its Compton wavelength).

The mass that a subatomic particle would need to have so that it would form a black hole when squeezed to its Compton wavelength is on the order of a Planck mass, which is around 10^19 more massive than a proton squeezed to radius 10^{-19} times smaller.

[Anonymous No.14542458]

how does raid5 use checksums/parity to recover data in case of the failure of a disk?
say I have 3 disks and each stores the checksum of the total data on all three disks, if one of the disks fails I can see how subtracting the total data of the other 2 from the total checksum is going to tell the program how much data was on the third, but how does it know how to correctly configure that amount of data into the exact information that was on the third disk?

[Anonymous No.14542892]

Retard here. I have these proofs in Spivaks book, and I'm starting to wonder whether doing the assignments is productive. They were a little to me, but I don't know if they're an efficient way for me to get a better mathematical foundation, since it's pretty much just applying what I already know. Can I just skip the problems? Or should I change books if my goal is just to have a thorough understanding of calculus?

[Anonymous No.14542914]

>>14541669
It's essentially [math]z_{ijk} = u_i v_j w_k[/math] for [math]z = u \otimes v \otimes w[/math]

[Anonymous No.14542951]

>>14536214
>stupid
Are there any *neutrino* bombs?

[Anonymous No.14542963]

>>14542458
Try asking here http://4chan.org/g/stupid

[Anonymous No.14542967]

>>14542458
Try asking here: >>>/g/stupid

[Anonymous No.14543008]

>>14542951
I had some dreadfully spicy jerk chicken yesterday and it's safe to say I got one brewing in my large intestine right now

[Anonymous No.14543122]

>>14542951
Neutrinos pass right through matter almost without interacting. We need huge tanks of water in mine shafts to even detect a little. If you could make a neutrino "bomb" it wouldn't harm anything.

[Anonymous No.14543287]

>>14542914
Sorry, I meant exterior product. Pic has more detail

[Anonymous No.14543317]

>>14543287
Oh. There isn't really a cute formula for all dimensions.
For three you can construct a matrix with columns [math]u, v, w[/math], compute the determinant and multiply by [math]e_1 \wedge e_2 \wedge e_3[/math].
You can prove it with the Levi-Civita symbol.

[Anonymous No.14543573]

Any freefem gods itt?
I am quite the beginner but managed to make some time dependant heat equation work on my mesh, like this : [math] \partial_t u(t,x,y)-D\Delta u(t,x,y) = f(x,y) [/math]
Now let's say I want a purely time dependant source term : [math] \partial_t u(t,x,y)-D\Delta u(t,x,y) = f(t) [/math], how do I deal with the [math] f(t) [/math] ? I tried modifying it in the time loop but freefem is telling my python-dwelling brain it's a "classic retard move". Do I have to define another subspace and project [math]f[/math] on it?
Any help would be appreciated pls.

[Anonymous No.14544117]

which 2hu is this?

[Anonymous No.14544129]

>>14543573
>real
>actually at most a sparse subset of the rationals with awkward distances from one another

[Anonymous No.14544276]

I'm gonna teach linear algebra for my humanities friend. which book should I use, shilov or linear algebra done right?

[Anonymous No.14544290]

what is a isomorphic number field? I can't wrap my head around the explanation given in the textbook

[Anonymous No.14544778]

>>14536214
Can the spring constant k ever be less then 1? At a value of say 0.5 for the spring constant, if you applied a force of one unit you would get 2 units of distance, this seems to be counterintuitive, although I'm not sure if the units for force and distance can be compared like this...

[Anonymous No.14544798]

going through my images folder, found a funny screencap of an undergrad lab report that i thought i'd share

[Anonymous No.14544824]

>>14540056
Just pick up an introductory textbook. You might need to brush up on mathematics first.

[Anonymous No.14544874]

>>14544276
>humanities
bro just count on your fingers

[Anonymous No.14544970]

I've got a intermediate quantum mechanics exam in a few days. I feel like I don't understand anything. The notes make sense when I read them, but when I'm given a question I often don't know where to start. What's the best way to revise in a few days?

[Anonymous No.14544980]

>>14544778
A constant of 0.5 means that to compress a spring by 2 meters you would need 1 Newton of force.
So yeah it's possible. It's just that such a spring that is so easy to deform would have funny use cases.

[Anonymous No.14545174]

Should I become a respiratory, or radiology tech? I like the job security that these 2 year degrees give.

[Anonymous No.14545424]

What is the summation in the Bellman Equation summing?
If T(s, a, s') is = P(s' |s, a)
then we are summing all probabilities of choosing a new state given the current state and action? Why aren't we just taking the max probability? What does adding all the probabilities do? Does it sum to one every time?

[Anonymous No.14545448]

>>14544798
kek

[Anonymous No.14545449]

>>14544117
Might not be a 2hu at all, but if it is, Jo'on or Wakasgihime, I think.

[Anonymous No.14545463]

>>14545449
I was wrong, it's Seiga.
https://mangadex.org/title/30b48588-6039-4375-81fe-2715884d0184/touhou-sogano-tojiko-wa-kataranai-doujinshi

[Anonymous No.14545537]

Why does [math]\langle{\psi}|{\psi}\rangle=1[/math] imply that:
[math] \langle \psi|\nabla|\psi \rangle = -\langle \psi|\nabla|\psi \rangle^*[/math]
?

[Anonymous No.14545850]

How does ((T-1) VT-1(s) + RT(s))/T = VT-1(s)+(1/T)RT(s)-VT-1(s) ?

In other words...
(3*5+2)/4 = 5+(1/4)(2-5)

I don't understand.
It's like magic. What are the steps in between this?

[Anonymous No.14545865]

how do I get good at nonlinear dynamics and nonlinear oscillators really quick if I've only taken up to Engineering ODEs and Linear Control Systems
I have had a very intriguing and promising insight that I want to explore involving kuramoto oscillators but I don't quite have the requisite background to really explore the situation

[Anonymous No.14545884]

>>14545463
excellent work, detective. i thought it was jo'on.

[Anonymous No.14545950]

>>14545850

[Anonymous No.14545957]

>>14545850
just pretend a and b are [math]V_{T-1}(S_1)[/math] and [math]R_T(S_1)[/math].
[eqn]\frac{(T-1)a+b}{T}\\=\frac{(T-1)}{T}a+\frac{1}{T}b\\=\frac{T}{T}a-\frac{1}{T}a+\frac{1}{T}b\\=1a+\frac{1}{T}(-a+b)\\=a+\frac{1}{T}(b-a)[/eqn]

[Anonymous No.14545972]

>>14545537
The expression you posted doesn't even make sense, do you mean [math]\langle \psi | \Delta | \psi \rangle[/math]?

[Anonymous No.14545977]

>>14536214
suppose i have board of 20x20 cells, and i have 13 identical pieces that i can place on said board, how many combinations could i make on the board? I don't necessarily have to place all the pieces.

[Anonymous No.14545978]

>>14545537
The divergence theorem implies that
[math]\displaystyle \langle\psi|\nabla|\psi\rangle +\langle\psi|\nabla|\psi\rangle^*=\int_{\mathbb R^n} \psi^*\nabla\psi+\psi\nabla\psi^* dV=\lim_{R\to\infty}\int_{|\vec x|\le R}\nabla|\psi|^2 dV = \lim_{R\to\infty}\oint_{|\vec x|=R} |\psi|^2 d\vec S[/math].
Now, we note that
[math]\displaystyle \langle\psi|\psi\rangle=\int_{\mathbb R^n} |\psi|^2 dV = \int_0^\infty dR \oint_{|\vec x|=R} |\psi|^2 dS[/math]
converges, which means the integrand must go to zero as R∞, so by the triangle inequality

[math]\displaystyle \biggl|\oint_{|\vec x|=R} |\psi|^2 d\vec S\biggr| \le \oint_{|\vec x|=R} |\psi|^2 dS\underset{R\to\infty}{\longrightarrow} 0[/math]

[Anonymous No.14546004]

>>14545977
Are you referring to unique combinations (two combinations are identical if through rotations and reflections they may be called isomorphic) or simply all possible combinations?

[Anonymous No.14546009]

>>14546004
all possible combinations

[Anonymous No.14546013]

>>14546009
Then it's simply 400 choose 0 + 400 choose 1 + 400 choose 2... + 400 choose 13.
n choose r is evaluated to be n! / ((n-r)! * r!)

[Anonymous No.14546034]

>>14546013
Thanks! Didn't expect it to be this simple, I've really over complicated it for myself.

[Anonymous No.14546061]

>>14545978
>just boldly integrates vectors fields on [math]dV[/math]
Based nonsensechad.

[Anonymous No.14546090]

>>14545957
Thank you

[Anonymous No.14546197]

>>14546061
You just integrate componentwise, there's nothing nonsensical about it. How else would you interpret [math]\langle \psi|\nabla|\psi\rangle[/math]?

[Anonymous No.14546247]

>>14536214
Can somebody spoon feed me some quality books to rekindle my passion for engineering? I’m burned out from my unga-bunga pencil pushing engineering job, and I’d like to rebuild myself in preparation for something better. Anything electrical is cool with me, though primary interests are telecom and signal processing.

[Anonymous No.14546285]

>>14546197
>You just integrate componentwise, there's nothing nonsensical about it.
Then your post doesn't make sense.
[math]\displaystyle \langle \psi | \nabla | \psi \rangle +\langle \psi | \nabla| \psi \rangle^* = \lim_{R\to\infty}\oint_{|\vec x|=R} |\psi|^2 d\vec S[/math]
The term on the left is, according to you, a three-component vector (unless I'm misunderstanding what do you mean by integrating component-wise). But how do you integrate the term on the right component-wise to get a vector when it's a regular number-valued surface integral?
Further, I can construct a counterexample easily enough for [math]\psi: \mathbb{R} \to \mathbb{R}[/math]. Set [math]\phi (x) = 1/x \cos (x^4)[/math]. Define [math]\psi(x) = \phi (x)[/math] when [math]|x| \geq 1[/math] and stitch in some smooth bounded function for [math]|x| < 1[/math]. Then [math]\psi(x) \dfrac{d}{dx} \psi (x) = - \dfrac{1}{x} \cos (x^4) \dfrac{4x^4 \sin (x^4) + \cos(x^4)}{x^2}[/math], which isn't even integrable on [math]\mathbb{R}[/math].
>How else would you interpret [math]\langle \psi | \nabla | \psi \rangle[/math]?
I think he just posted it incorrectly and meant [math]\langle \psi | \Delta | \psi \rangle[/math].
Which, mind you, doesn't actually work under the conditions he posted, but it does work if you assume [math]\psi[/math] is in the Schwartz space, which physicists usually do willy nilly.

[Anonymous No.14546305]

>>14545972
Why? It's from a book. [math]\nabla[/math] is the gradient

>>14545978
Wait how can you apply the divergence theorem here [math]\int_{|\vec x|\le R}\nabla|\psi|^2 dV[/math] ? [math]\psi[/math] is a scalar function, so [math] \nabla[/math] is a gradient, not a divergence, right?

>I think he just posted it incorrectly and meant ⟨ψ|Δ|ψ⟩
Actually no, see pic related, it's the book

[Anonymous No.14546309]

>>14546285
Note that i write dS as a vector, so the right-hand term is also a (n-dimensional) vector. I even double checked the application of the divergence theorem, pic rel

[Anonymous No.14546320]

>>14546247
Nonlinear Dynamics and Chaos by Steven Strogatz

[Anonymous No.14546372]

>>14546309
>Note that i write dS as a vector, so the right-hand term is also a (n-dimensional) vector.
Right, sorry.
Honestly your computation might just be correct and the only issue is that you just can't assume that the thing exists.
Unless the function I gave in >>14546285 actually goes to zero at infinity and I'm just blind.

[Anonymous No.14546410]

>>14546372
Oh, my bad, the function is just integrable.
Sorry for wasting everyone's time.

[Anonymous No.14546456]

>>14546410
Your example seems to prove that you can't assume absolute/Lebesgue integrability, but conditioned integrability *i think* follows from my computation.
I was worried about mega-oscillatory wavefunctions but it seems to average out surprisingly well in the integral

[Anonymous No.14546468]

reposting this from fit on the off chance someone here knows anything about this.

I have been reading into the effects of TRT on obese people for reasons, and I have a problem. I don't really know how it is that elevating testosterone to within reference levels produces sustained (multi-year) fat loss and muscle gain even within reference levels, for non-obese people. I have a suspicion that extraneous testosterone in the blood has a higher bioavailability in some fashion, whether by existing in a greater unbound state than normal due to its way of entering the blood, or by some chemical fuckery that I as an untrained retard don't know of. Does anyone here have any info or resources they can point me to on this?

[Anonymous No.14546494]

>>14543317
Thanks

[Anonymous No.14546611]

Should I use multiple sources for self study or should I stick to just one? I wanna learn calculus with Apostol's book and I was wondering should I just stick with it and just use some other resources if I'm stuck or should I learn the same concept multiple times from different sources?

[Anonymous No.14546651]

Why do some mathematical problems have no closed-form solution? Is it because no closed-form solution was found yet or is it because there's something about these problems that makes finding a closed-form solution impossible?

[Anonymous No.14546662]

>>14546611
I personally learn from a single source and then compare it with other sources when rereading. The author might answer my questions later on in the text and I don't want to confuse myself by reading other stuff before getting the full picture.

[Anonymous No.14546698]

>>14546662
Thanks for the insight.

[Anonymous No.14546898]

>>14546320
Thanks, anon. I’ll check it out.

[Anonymous No.14546992]

>>14539625
Late response but thanks.

[Anonymous No.14547037]

>>14539625
>inner products and quadratic forms are the same thing
Inner products are quadratic forms, I mean.
I phrase things very awkwardly sometimes.

[Anonymous No.14547209]

>>14536214
Why is this 2/3 when the probability of missing is 1/3?

[Anonymous No.14547506]

anyone skilled in zemax or similar software itt? need to do a project or two in it and not sure what would be some good ones for the resume

[Anonymous No.14547516]

How do you estimate a mean of one variable using another "Auxiliary" variable?

[Anonymous No.14547786]

Problem : What's the likelihood of teams A and B going 7 games (both win 3 games) in a 7 game series if each team has a 1/2 probability of winning any given game?

First approach:
[eqn]P \ = \ \ 2 \ * \binom{6}{3} \ * \ \left(\frac{1}{2}\right)^6 \ = \frac{20}{32}[/eqn]

Why does removing the 2 give the correct answer? I originally put it there to account for both A and B.

[eqn]P \ = \binom{6}{3} \ * \ \left(\frac{1}{2}\right)^6 \ = \frac{10}{32}[/eqn]

Is my translation correct?: Given a 6 game set, we need to choose one team to win 3 games, and each of these possibilities has a [eqn]\frac{1}{64} [/eqn] chance of happening, so the other 3 games have to go to the other team.

[Anonymous No.14547839]

Suppose some some set (of numbers/group elements) has the cocycle condition [math]s_{ab}s_{bc}s_{ca}=1[/math] for all a,b,c. How can I prove that [math]s_{ab}s_{ba}=1[/math]?

[Anonymous No.14547956]

I have a math question in my book that reads:
>The product of two even numbers that follow each other is 728. Find the numbers.

I don't know how I would go about doing this, all I can think of is a naïve method where I systematically divide 728 by even numbers until a get an even quotient that is in proximity, but that clearly can't be the answer.

[Anonymous No.14547965]

>>14547956
An even number is of the form 2n for an integer n.
So then there exists some n for which
2n(2n+2) = 728
4n^2 + 4n = 728
n^2 + n - 182 = 0

This is a quadratic equation. Solve it to find n

[Anonymous No.14547968]

>>14547839
s_bc * s_ca = s_ba so the result follows by direction substitution

[Anonymous No.14547975]

>>14547965
Ahhhh, thanks!

[Anonymous No.14548004]

>>14547209
because the [math]p[/math] parameter for the geometric law is the probability of success, not failure

[Anonymous No.14548033]

>>14545972
[math]\nabla[/math] is often used to denote the 3d momentum operator: [math]\boldsymbol{\hat{p}} = -i\hbar\nabla[/math]

>>14545537
Probably follows from the fact that

[math]\begin{align}
\langle\psi | \dfrac{i}{\hbar} \boldsymbol{\hat{p}}| \psi\rangle &= \dfrac{i}{\hbar} \int \langle\psi | \boldsymbol{\hat{p}}| p\rangle \langle p| \psi\rangle dp \\
&= \dfrac{i}{\hbar} \int \langle\psi | p\rangle p \langle p| \psi\rangle dp \\
&= \dfrac{i}{\hbar} \int \psi^{*}(p)\ p\ \psi(p) dp
\end{align}[/math]

[Anonymous No.14548241]

>>14547968
Thanks, but I'm unable to derive s_bc * s_ca = s_ba from s_bc * s_ca * s_ab = 1

[Anonymous No.14548478]

>>14536214
I'm having a bit of trouble with magnetic dipoles and magnetic moments. With electric dipoles it's easier to conceptualize because you have a negative and positive charge, but how does this work with magnetism?

So say we have an electron orbiting a proton, how would the dipole look? What would be the north and south pole of the "magnet"?

And regarding the moment: "The electric dipole moment is a measure of the separation of positive and negative electrical charges within a system..." So would it be the seperation between the north and south poles and where do they position themselves with an orbiting electron?

[Anonymous No.14548638]

If I heat iron to 1000°C and allow it to cool down – will it be exactly the same as before heating? Or will transition to austenite and back leave a mark?

[Anonymous No.14548708]

>>14548638
bike cogs are usually chromoly steel. 1000C sounds hot enough to ruin it but idk

>Heat Treatment - AISI 4130 steel is heated at 871°C (1600°F) and then quenched in oil. This steel is usually heat-treated at temperatures ranging from 899 to 927°C (1650 to 1700°F).
>Forging of AISI 4130 steel can be performed at 954 to 1204°C (1750 to 2200°F).
>Hot working of AISI 4130 steel can be done at 816 to 1093°C (1500 to 2000°F).
https://www.azom.com/article.aspx?ArticleID=6742

[Anonymous No.14548751]

>>14536214
>>where can I look up if the question has already been asked here?
>archived.moe/sci
Error!
Sorry, this board does not have search enabled.

[Anonymous No.14548755]

>>14548751
use >>/sci/

[Anonymous No.14548957]

>>14536214
Is
[math] \nabla |\vec{B}|^2 = \nabla B B = 2 \cdot 5 = 10 [/math]
correct when
[math]B = 2, \nabla B = 5 [/math]?

I just picked random values for the gradient and B, just want to see if that is allowed.

[Anonymous No.14548999]

>>14537156
The Equation says the Value function V is the maximum of the righthand side over all possible actions a. Notice the righthandside (without the max) would still depend on a. The max basically says that we plug in the best a, such that from all possible a, we maximize the right side. In simple terms: Pick an a, plug it in, calculate the result. Pick another a, calculate the result, is it bigger or smaller? If larger, the first action was not a maximizer. The equation formally says that V is the maximum when you have the best action plugged in. How you encode your actions is another thing, for your game 0 to 3 eould work but remember, you have to plug them into the equation before you can judge if one is better than the other.
Don't want to sound mean but I think you need a grasp of basic mathematics before you can start to go for Bellman Eq. Their theory are a bit more involved, especially in the continuous setting. Also most Bellman equations you find on the internet are reduced and formally not correct (like this one I suppose), it's more of a formal statement of the Dynamic Programming principle.

[Anonymous No.14549038]

Trying to understand categorical limits. Let [math]A = \mathbb{Z} / 2 \mathbb{Z}[/math]. We have standard inclusions [math]A^n \to A^{n+1}[/math] (add an extra 0). Would it be correct to describe [math]\text{colim}_{n \in \mathbb{N}} A^n[/math] as the group of all finitely supported binary sequences (the group action being addition mod 2)?

[Anonymous No.14549049]

>>14548957
No
The gradient of a scalar is a vector

[Anonymous No.14549090]

>>14548957
[math]
\nabla(|B|^2)=\nabla(B\cdot B)=(\nabla B) B + B (\nabla B)=2B(\nabla B) \\

[/math]
Now, let's say [math]B=5x, \nabla B = (5,0,0)[/math] at x=2/5, where [math]B=2[/math] and [math]|\nabla B|=5[/math].
So,
[math]
\nabla(|B|^2)|_{x=2/5}=2*5*2/5*(5,0,0)=(20,0,0)
[/math]
Obviously this all depends on B. If B is a vector it's a bit different as well.

[Anonymous No.14549390]

>>14549090
>>14549049
AAAAAAAAAAAAaaaaaAAAAaa, alright, thanks anons. You guys are right.

>Mfw another hr of sleep subtracted because of this shit.

[Anonymous No.14549646]

This question is dealing with big-Theta notation and finding a lower bound, but i think its more about a sum.

Can someone tell me how/why they magicked this unholy sum into existence?

What significance does n^2/4 have? if i choose n=5, then i get n^2/4=6.25 when n=5 sums to 15.

What is the point in making something so insanely complicated looking, i can't even figure out what the equal sign is referring to when they alternate it with the greater or equal inequality sign.

Pls help

[Anonymous No.14549793]

>>14549646
>What significance does n^2/4 have? if i choose n=5, then i get n^2/4=6.25 when n=5 sums to 15.
For some n, f(n) is always bigger than n^2/4.
To get there, you punch your function until is has the form you want. That's the ugly floor function and inequality shit.
Don't bother, the details are not important.

[Anonymous No.14549908]

>>14549793
okay tyvm anon i appreciate it

so i just find a function that is as close to f(n) as possible but always smaller than it?

[Anonymous No.14549939]

>>14549646
Ok, but that is such an ugly way of solving it. That sum equals n(n-1)/2 = (n^2-n)/2 = Omega(n^2).

https://en.m.wikipedia.org/wiki/1_%2B_2_%2B_3_%2B_4_%2B_%E2%8B%AF

Just remember that or prove it once using induction or a different method (since induction doesn't give intuition usually).

[Anonymous No.14549947]

>>14549939
My bad, it should be n(n+1)/n. I'm rusty, forgive me.

[Anonymous No.14549950]

>>14549939
My bad, should be n(n+1)/2, I'm rusty. Forgive me.

[Anonymous No.14550010]

>>14549939
>>14549950
ty anon i will check out the link

[Anonymous No.14550066]

>>14548755
>warosu is archiving /sci/ again
Nice.
>>14549038
Yes.
The gluing condition [math]A^n \to A^{n + 1}[/math] ensures that each finite binary sequence is mapped to a single value by and homomorphism from the tower to a group.

[Anonymous No.14550068]

would you recommend doing masters thesis with something I'm already familiar with or rather something new (and possibly more interesting)?
to be more specific, i can't make my mind up between doing something with NLP, with which I'm working for almost a year now or quantum machine learning
something I'm afraid of, is that I'll simply not have enough time to make something worthwhile with QML, while with NLP i can get straight to work

[Anonymous No.14550130]

>>14547839
You can't derive it: it's false.
Consider [math]s:\mathbb R^\times\times \mathbb R^\times \to\mathbb C^\times,\quad s_{a,b}=\frac{a}{b}e^{i2\pi/3}[/math].
The complex factor disappears in your cocycle condition, but not in the latter expression.
If you know, however, that your output group doesn't have any nontrivial cube roots of unity, then it follows directly from [math](s_{a,b}s_{b,a})^3=1[/math]

[Anonymous No.14550137]

>>14536214
How would I go about developing a colored hand sanitizer that would turn colorless after 20 seconds?
Need to come up with ideas to help in the fight against covid, for a report.

[Anonymous No.14550158]

>>14550137
changing color after 20 s would also be fine.

[Anonymous No.14550168]

Requesting answers on a 'Physics of Music' exam: >>>/wsr/1216484

[Anonymous No.14550279]

>>14536214
Hey anons. I'm currently studying convex optimization, and I really enjoyed it. However, I also suck at it. How do I prepare myself and self study the subject? I have little to no prior experience with "proof" class in general, so is it recommended for me to go back to the basic? Thank you.

[Anonymous No.14550379]

>>14550137
>to help in the fight against covid

i guess you could use some easter egg dye

[Anonymous No.14550517]

>>14550279
> I have little to no prior experience with "proof" class in general, so is it recommended for me to go back to the basic?
I'd personally recommend going over more rigorous texts on linear algebra and calculus (say, Spivak and Lang) so you can familiarize yourself with proofs and proof strategies using a subject you have a solid grasp of.

[Anonymous No.14550533]

>>14550517
Thank you anons. I guess I should spend some time to study regular proof method then.

[Anonymous No.14550537]

>>14550517
I'm not the anon you're replying to, but I have a similar question, right now I'm studying high school math, should I wait until calculus to start doing proofs? Some exercises in the book require me to prove stuff and that's the part where I struggle the most.

[Anonymous No.14550675]

>>14550537
Don't ask me specifically, it's rude to everyone else in the thread.
But no, you shouldn't. Failing and skipping exercises is fine, but there's no actual reason to wait until you're out of high school to start doing proofs.
Just follow the three step program:
>try to picture the thing you're trying to prove and reason it out to yourself. Verbally. Out loud if you don't have an inner voice
>reread the chapter to see if there are any useful results or proof techniques
>give up on the exercise if you're still not done

[Anonymous No.14550759]

[Anonymous No.14550864]

>>14546372
nice tits

[Anonymous No.14551380]

>>14536214
Curious, what are some 'impressive' paper that came out of china? Preferably mathematic.

[Anonymous No.14551584]

If wind is defined as a movement of air in horizontal direction, then how do you call a movement of air in vertical direction?

[Anonymous No.14551612]

i got a question on my chemistry book:

the mass of a diamond is 3,1mg.
a) how many atoms of c13 are present if the carbon content is of 1,1% atomics of this isotope?

and the formula:
0,0031g/(12,011g/0.6022 x 10^24) = 1,55 x 10^20C atoms
now, (1,55 x 10^20)(0,011) = 1,7 x 10^18C^13 atoms

and now for b): base 3,1mg
mass13/mass total = (1,7 x 10^18)(13 units of atomic mass)/(1,55 x 10^20)(12,011 units of atomic mass) = 1,2% Wt

now my question is, how the fuck does this number 13 units of atomic mass in b) appears? where does (1,7 x 10^18)(13u) comes from? 1,7 is the latter result but why 13u? how i can get to this conclusion?

b) what's the weight percentage of this isotope?

[Anonymous No.14551616]

>>14551612
i just fucked up the last paragraph. i just want to know why there's a 13u, why is 31 backwards?

[Anonymous No.14551728]

It's 2pm and I am having a blood test 8am tomorrow, if I drink an energy drink will that excess sugar show in my bloodwork

[Anonymous No.14551748]

>>14550675
Sorry if I sounded rude, it wasn't my intention, just asked you specifically because you answered a similar question to the other anon.
Thank you for the advice.

[Anonymous No.14551754]

>>14551612
Because that is how much a c13 isotope approximately weighs. the number of an isotope represents its mass number and you can basically treat it as the weight. It is not exactly accurate but it's enough for these calculations.

[Anonymous No.14551769]

>>14551754
so the 13 basically comes from the isotope like an atomic number from any element? fuck how i didnt figured it out thanks anon

[Anonymous No.14551803]

>>14551769
Yes, that's like entry level chemistry knowledge. Normally isotopes are described as "element-mass number", because the different number of neutrons alone (that defines an isotope) have little use in calculations and it's more useful to use mass number which is atomic number + neutron bomber.

[Anonymous No.14551889]

Say you have a parametric 2D closed curve. Which one is considered de positive orientation?

[Anonymous No.14551922]

How you do your research? What is the most reliable way to get good accurate papers?

[Anonymous No.14551976]

>>14551889
Jordan closed curve guarantees that the curve has an inside and an outside.
The positive orientation is the one where the velocity vector and the inwards-normal form an oriented basis in [math]\mathbb{R}^2[/math].
For non-differentiable curves I think you define it via homotopy/homology. Remove a point from the interior, ask for the curve to have the same homotopy/homology as a counter-clockwise circle around the point.

[Anonymous No.14552044]

>>14550759
bump

[Anonymous No.14552235]

I know what a determinant is. I know how to compute it with Laplace Expansion.
But WHY does it work?
Can anyone explain the reasoning or motivation behind it, or point me in the right direction?

[Anonymous No.14552273]

>>14552235
https://youtu.be/sZ2qulI6GEk?t=1m5s

[math]
\sum_{n=0}^{\infty} a_n x^n = A(x) \\
\sum_{n=0}^{\infty} a(n) x^n = A(x) \\
a(n) \sim \! \sim \! \sim \! \! \! > A(x) \\
a(n) = 1 \sim \! \sim \! \sim \! \! \! > \frac{1}{1-x} \: \: \, ,\: \: \: \left | x \right | < 1 \\
a(n) = \frac{1}{n!} \sim \! \sim \! \sim \! \! \! > e^x \\
\text{continuous analog:} \\
\int_{0}^{\infty} a(t) x^t dt = A(x) \: \: \, ,\: \: \: 0 < x < 1 \Rightarrow ln(x) < 0 \\
x^t = \left ( e^{ln(x)} \right )^t \: \: \, ,\: \: \: -s = ln(x) \Rightarrow x = e^{-s} \\
\int_{0}^{\infty} f(t) e^{-st} dt = F(s) \\
f(t) \xrightarrow[~~~~~]{ }
\boxed{transform} \xrightarrow[~~~~~]{ } F(s) \\
f(t) \xrightarrow[~~~~~~~]{ }
\boxed{operator} \xrightarrow[~~~~~~~]{ } g(t) \\
[/math]

[Anonymous No.14552275]

>>14552273
dude, Laplace EXPANSION, not TRANSFORMATION
the thing you use to calculate determinants

[Anonymous No.14552288]

>>14552235
wiki has the proof

[Anonymous No.14552331]

>>14552288
Yes, but it's a bit raw for someone like me who just knows introductory Linear Algebra.
I was thinking if someone knew some resource like 3b1b that explains it well, or at least is hand-holding you through the process, with the idea in mind that the target reader is someone like me (on the level of someone learning Linear Algebra).
I mean, they had to come up with the idea somehow. They needed to have some motivation to consider it. And that seems like a pretty basic concept in linear algebra, so it can't be that hard, right?

[Anonymous No.14552372]

>>14552331
https://math.stackexchange.com/questions/590164/geometric-interpretation-of-the-cofactor-expansion-theorem

[Anonymous No.14552404]

>>14552372
>that second answer
Stackexchange has such stupid fucking answers sometimes.
He could have just written "[math]a_1 \wedge a _2 \wedge \ldots a_n = \sum_{i = 1}^n a_{1 i} e_1 \wedge a_2 \ldots a_n[/math] bada bing bada boom Laplace expansion".

[Anonymous No.14552408]

>>14552404
*[math]a_1 \wedge a _2 \wedge \ldots a_n = \sum_{i = 1}^n a_{1 i} e_i \wedge a_2 \ldots a_n[/math]

[Anonymous No.14552414]

I don't understand how attractive and repulsive forces work.
Are there little things in the air pushing things apart?
Why can two magnets just attract each other?
When I pull on a cloth, the rest of the cloth comes with it, so what is something combining them?
Pushing is easy for me to understand, i push something, it moves in the opposite direction from me. And things can push each other. But how they can attract each other doesn't make sense to me. And also how magnets can repel each other even though there's air between them.
It hurts my head thinking about it.
There's probably some simple way of explaining it thats not even scientific but my brain is so dug deep into this hole that I can't even see it clearly.

[Anonymous No.14552431]

>>14552404
"What does ∧ mean?" from OP almost made me spit out my drink.

[Anonymous No.14552468]

Anyone know how to do this? Walk me through it at least I suppose. I believe the answer is 15.39 yd^2 but I might be dumb. It might also be 127.17 yd^2

[Anonymous No.14552481]

>>14552414
How could anyone answer the question you’re asking? The fact is things DO attract and repel each other. We have mathematical laws that predict very precisely what the effects are of those attractions and repulsions are. You have an intuition about pushing and pulling, and you want to tell yourself a story about how you can understand the other types of pushing and pulling in terms of your limited intuitions from everyday experience, but there is no such story. You’re explaining things in the wrong direction. You need to start from the laws and explain why you have the intuitions you do, rather than expected all the laws to conform to your intuitions.

[Anonymous No.14552487]

>>14552468
Or maybe 5.13 yd^2, sucks to be dumb guys

[Anonymous No.14552493]

>>14552468
>It might also be 127.17 yd^2
Please think for a moment whether this is reasonable.

[Anonymous No.14552511]

>>14552493

Yeah no it's not.

[Anonymous No.14552513]

>>14552468
When you realize that the triangle's height is the same as the radius of the semicircle, then you should instantly see the solution.

[Anonymous No.14552514]

how do I stop feeling depressed

[Anonymous No.14552521]

>>14552513
I apologize but I do not, I may be extremely stupid, is the answer 5.13 yd^2?

The radius of the circle is 14.13 yd^2 and I believe the area of the triangle is 9...so 14.13 - 9 is 5.13? I'm basically guessing.

[Anonymous No.14552534]

>>14552521
The area of the semicircle is 14.13, not the radius of the circle.

Area of semi-circle - area of triangle = the area of the shaded region

[Anonymous No.14552546]

>>14552521
Be more confident.

[Anonymous No.14552560]

>>14552431
>it really lives in Λn−1V ;)
>what's the wedge thing
>disregard it, I was just showing off a bit, it doesn't actually matter for the answer
>NO NIGGA I'M STILL CONFUSED WHAT'S THE THINGY WHAT DOES IT MEAN
Hilarious.

[Anonymous No.14552561]

>>14552514
Treatment is simple. Great clown Pagliacci is in town tonight. Go and see him. That should pick you up.

[Anonymous No.14552572]

>>14552560
desu I have no idea what that thing is either
it feels like the guy is pulling a modern-day howitzer against a trebuchet, which is exactly the opposite of what I had in mind
I'll rephrase my question then: is it even possible to explain it in terms of, lets say, HS level of math knowledge?

[Anonymous No.14552607]

[Anonymous No.14552625]

[Anonymous No.14552696]

>>14552572
I can't, I have to bare minimum assume familiarity with linear algebra.
You want to compute the n-dimensional volume of the parallelepiped-thingy associated with the vectors [math]v_1, \ldots, v_n[/math].
So, we write [math]v_1 = u + w[/math]. We call the operator that projects onto the one-dimensional space orthogonal to [math]v_2, \ldots, v_n[/math] by [math]P[/math].
So the volume spanned by [math]v_1, \ldots v_n[/math] is the same as the volume spanned by [math]P(v_1), \ldots, v_n[/math]. Since [math]P(v_1) = P(u) + P(v)[/math] we can also notice that this volume is the volume spanned by [math]P(u), v_2, \ldots v_n[/math] plus the volume spanned by [math]P(w), v_2, \ldots, v_n[/math].
However, the volume spanned by [math]P(u), v_2, \ldots, v_n[/math] is the same as the volume spanned by [math]u, P_u (v_2), \ldots, P_u(v_n)[/math], where [math]P_u[/math] is the projection on the space orthogonal to [math]u[/math], and similarly for [math]v[/math]. That's the Laplace expansion, where [math]u[/math] and [math]v[/math] are all of the [math]n[/math] one-entry vectors that sum to your last column.

[Anonymous No.14552771]

a metal for welding contains 60% tin and 40% lead. what's the atomic percentage of each element?
answer: 72% Sn 28% Pb

but how?

[Anonymous No.14552800]

>>14552696
I think I kinda start to understand it now, but I'm still wondering about the reasoning behind the alternating +/- signs in the expansion

[Anonymous No.14552820]

>>14552771
>but how?
what's the atomic mass of tin and lead?

[Anonymous No.14552867]

>>14552800
Orientations are such a pain in the ass to explain.
The volume spanned by [math]e_k, e_1, \ldots, e_{k - 1}, e_{k + 1}, \ldots, e_n[/math] is [math](-1)^k[/math] because it takes [math]k[/math] swaps to bring [math]e_k[/math] to the beginning.
If [math]P_{e_k} (v_2), \ldots, P_{e_k} (v_n)[/math] has the same volume as [math]\lambda e_1, \ldots, e_{k - 1}, e_{k + 1}n \ldots, e_n[/math] then [math][math]e_k, P_{e_k} (v_2), \ldots, P_{e_k} (v_n)[/math] has the same volume as [math]e_k, \lambda e_1, \ldots, e_{k - 1}, e_{k + 1}n \ldots, e_n[/math], which is [math]\lambda (-1)^k[/math]

[Anonymous No.14552871]

>>14552867
*[math](-1)^{k - 1}[/math]

[Anonymous No.14552928]

Anyone mind adding me on discord to help me understand functions and graphing? I have a question on something specifically and feel like I'm thinking too much into it.

Kongou#2106

[Anonymous No.14552945]

>>14552867
ok, that makes sense
you're doubting your ability to explain things, but you're doing a good job actually

[Anonymous No.14552970]

>>14552625
Is the answer to this:
[math] SIL = 76 = 10log(\frac{I}{I_0})
\rightarrow I =\approx 1.99^{-9} [/math]

so the trombone is 130x louder, so it's 23 db greater. So final SIL reading is 93?

[Anonymous No.14552991]

>>14552945
>you're doubting your ability to explain things
I'm not, I have the best explanations and intuitions this side of the Mississipi.
Orientations are just a pain to verbalize.

[Anonymous No.14552997]

>>14552820
>>14552820
118,71 and 207,2 respectively whats your point?

[Anonymous No.14553019]

Can anyone give the intuition behind a holomorphic [math]f(z)[/math] being independent of [math]\bar{z}[\math]?

I sort of get that you use the Wirtinger derivatives to show this, but we are actually talking about independence of [math]\bar{z}[/math] in the context of the coordinate change [math]z \mapsto (z,\bar{z})[/math], right?

It occured to me when I was given the integral [math]\int_{\gamma}f(\bar{z})dz[/math], where [math]\gamma[/math] is the unit circle and f is entire. It's an easy problem that can be solved with Cauchy's integral formula after a parameterization, and the answer is [math]f'(0)2i\pi[/math].

However, if we talk about this notion of [math]f(z)[/math] being "independent of [math]\bar{z}[/math]", this integral would vanish since we would consider [math]f(z)[/math][ constant with respect to [math]\bar{z}[/math], right? This is absurd though, and it is clearly not true. So what do we actually mean by this? How is it useful?

[Anonymous No.14553034]

>>14553019
Okay so I messed this up completely, here's what I meant:

Can anyone give the intuition behind a holomorphic [math]f(z)[/math] being independent of [math]\bar{z}[/math]?

I sort of get that you use the Wirtinger derivatives to show this, but we are actually talking about independence of [math]\bar{z}[/math] in the context of the coordinate change [math]z \mapsto (z,\bar{z})[/math], right?

It occured to me when I was given the integral [math]\int_{\gamma}f(\bar{z})dz[/math], where [math]\gamma[/math] is the unit circle. It's an easy problem that can be solved with Cauchy's integral formula after a parameterization, and the answer is [math]f'(0)2i\pi[/math].

However, if we talk about this notion of [math]f(z)[/math] being "independent of [math]\bar{z}[/math]", this integral would vanish since we would consider [math]f(z)[/math] constant with respect to [math]\bar{z}[/math], right? This is absurd though, and it is clearly not true. So what do we actually mean by this? How is it useful?

[Anonymous No.14553063]

>>14552997
s - amount of tin atoms in the alloy
p - amount of lead atoms in the alloy
m - whole mass of the alloy

m = 118.71s + 207.2p
118.71s = 0.6m
207.2p = 0.4m

(118.71s)/(207.2p) = (0.6m)/(0.4m)
s/p = 2.6181

s/(s+p) = (s/p) / (s/p + 1) = 0.72
p/(s+p) = 1 / (s/p + 1) = 0.28

[Anonymous No.14553093]

someone please help me with 3ab

[Anonymous No.14553382]

>>14552970
[math]76+10 \log_{10}130=97.14[/math]
>>14553093
the fourier spectrum of a sinusoid is just a spike at its frequency, nothing else

[Anonymous No.14553394]

>>14553063
thanks bro you are god sent

[Anonymous No.14553632]

>>14553382
Very cute image.

[Anonymous No.14553636]

>>14553632
ty

[Anonymous No.14554139]

If H is a subgroup of G then center of G is a subgroup of H, right? Or is there any simple counterexample thst eludes me?

[Anonymous No.14554400]

what happens if in a jacobian matrix there's an eigenvalue that's positive, and one that's 0? does the stability in the first approximation still apply? or am I supposed to use Lyapunov? also, what if there's an eigenvalue that's 0 and one that's negative?

[Anonymous No.14554469]

>>14554400
No it does not, you can use center manifold theory to approximate the center manifold, which then has equivalent properties as the original system in terms of asymptotic stability. It is a bit more tedious, but if your system is small it's not a problem.

[Anonymous No.14554487]

>>14554469
I am not sure what center manifold theory is, from what I see on the internet we haven't studied that

[Anonymous No.14554500]

>>14554487
What is the system you are working with?

[Anonymous No.14554505]

>>14554500
pic rel
I calculated the equilibrium points, and I found 3 of them (0,0), (1,1) and (-1,-1)
every time I input these points in the jacobian matrix I get a null eigenvalue

[Anonymous No.14554804]

how do I find the stability of the equilibrium points in this equation? the equilibrium points that I found are a and +/- sqrt(3) * i
by using the stability in the first approximation criterion I deduced that only a can be stable equilibrium point since the derivative of the function on the RHS when I inputted a was always negative
however, when I do the same for the other points, I get a complex answer and I don't think a can take any values there since it's supposed to be a real parameter
what am I doing wrong?

[Anonymous No.14554969]

>>14553632
why did my post get deleted? im on different wifi so i cant check if i was b& or anything

[Anonymous No.14555101]

how can I destroy my sperm count?

[Anonymous No.14555772]

>>14555101
Smoke, drink, eat junk food, basically everything that rots away your body's ability to set aside nutrients for procreation.

[Anonymous No.14555795]

If a human is slingshotted at the sun from right outside Earth at the speed of light, what would kill them first, the heat as they get into contact with the star's atmosphere or would radiation kill them dead before ever reaching it?
(assuming they can survive the original slingshot and don't die from being in the vacuum of space)

[Anonymous No.14555804]

>>14555772
Is there a way to do it without fucking over my health? Surely there's some UV light or something I can shine on my balls for an hour every day or something?

[Anonymous No.14555873]

>>14555795
>at the speed of light
You'd turn into a fusion warhead. https://what-if.xkcd.com/1/

[Anonymous No.14555886]

>>14555873
Fucked up, that'd even happen in space? I guess the better question would be how long it'd take to die from naked exposure to the sun's rays.

[Anonymous No.14555997]

>>14547786
isn't this just team A winning exactly three games of the first six and probability is irrelevant?
C(6,3)/2^7 = 20/128

[Anonymous No.14556141]

back in my day we ran everywhere like men

[Anonymous No.14556289]

>>14553034
>I sort of get that you use the Wirtinger derivatives to show this, but we are actually talking about independence of z¯ in the context of the coordinate change z(z,z¯), right?
Well, no.
The context is the complexification of the tangent space. You start off with [math]T_p \mathbb{C}[/math], which is a real bidimensional vector space (even though [math]\mathbb{C}[/math] is complex) and replace it with [math]\mathbb{C} \otimes T_p \mathbb{C}[/math], which is a bidimensional complex vector space and where [math]\displaystyle \dfrac{\partial}{\partial z}[/math] lives.
>So what do we actually mean by this? How is it useful?
It's a really clean way to state Cauchy-Riemann.
It also enables us to talk about holomorphic vector fields and the like, but that's probably not interesting to you.
>>14554139
>If H is a subgroup of G then center of G is a subgroup of H, right?
No.
Consider G abelian.

[Anonymous No.14556383]

>>14554969
So were you v& or not?
In that minecraft server we used to play in, I mean.

[Anonymous No.14556490]

I'm doing the meme list and the author's sol of the proof is very verbose compared to mine.
Is it really necessary to state these or is the author just being autistic?

[Anonymous No.14556492]

>>14556490

[Anonymous No.14556521]

>>14556492
>division
divisibility*

[Anonymous No.14556582]

For the argument
p v ~q
~p
Therefore ~q

I can use both disjunctive syllogism and modus ponens to prove this is valid right?

[Anonymous No.14556615]

>>14556383
i guess not

[Anonymous No.14556627]

>>14556490
>>14556492
The problem with this proof is that you're sweeping the point of the question under the rug; why is b/4 an integer? Assuming this is basically just assuming the proposition.

I don't like the book solution either, though, because while correct, it's also burying the point of the problem under a bunch of braindead algebra.
The point of the problem is that if you have a prime number p, and it divides ab, then either p divides a or p divides b. 7 doesn't divide 4, so it has to divide a.

[Anonymous No.14556634]

>>14556492
No, you've skipped the important step, which is showing that b/4 is an integer.
Consider doing the same proof but with 7 instead of 4. Your argument goes
[math]a=\frac{7b}{7} = 7\frac b7[/math], "thus a = 7c for integer c = b/7", but obviously this doesn't work, because b/7 isnt always an integer.

[Anonymous No.14556751]

>>14555997
whoops it's C(6,3)/2^6 = 40/128 = .3125
experimentally confirmed it at .311737 over 1000000 trials
weighted case is just C(6,3)*(p)^3*(1-p)^3

[Anonymous No.14556790]

>>14554804
x=a is the only real equilibrium point, and is stable. The complex equilibrium points have second derivatives with positive real part and so are unstable.

E.g. for x=i√3, substitute x=i√3+δ to get

x' = δ(-δ^2+aδ+6 + i((2√3)a-(3√3)δ))

As δ->0, x'->δ(6 + i(2√3)a). This is the linearisation of the derivative about the equilibrium point.

x'=kδ with real negative k means that the derivative is opposite the deviation, i.e. back toward equilibrium => stable. x=kδ with real positive k means that the derivative is toward the deviation, i.e. away from equilibrium => unstable. x=kδ with imaginary k means that the derivative is perpendicular to the deviation (multiplication by i = rotation by 90°), which doesn't affect stability. x=kδ with complex k spirals inward (back toward equilibrium) if the real part of k is negative and spirals outward (away from equilibrium) if the real part of k is positive.

[Anonymous No.14556912]

https://play.google.com/store/apps/details?id=cos.premy.mines

does anyone understand how this works?

[Anonymous No.14556917]

>>14556912
Looks like it's just Minesweeper? Stop shilling your shitty app Anon.

[Anonymous No.14556922]

>>14556917
Yea I'm shilling a fucking game that got updated over a year ago...
Apparenrlt it's Minesweeper in 3D but I don't understand how to solve it

[Anonymous No.14556934]

>>14556922
Anyways I got it. Now I can go sleep
Cya nerds

[Anonymous No.14557469]

>>14556582
I don't think you can directly use modus ponens here.
Modus ponens is usually given as:
[math]\frac{\lnot p \lor q, p}q[/math]
But thats not what you have here. It might seem intuitive, that you should still be able to use it, since [math]p \vdash \lnot \lnot p[/math] but you can't just make substitutions like this inside a formula (at least not in the proof systems that I learned).
You *could* use modus ponens to solve this, but it would involve multiple steps and a subproof.
hmu if you want to know how.

[Anonymous No.14557473]

>>14557469
Oh wait, I might be stupid.
Yes after using [math]\frac{p}{\lnot \lnot p}[/math] on [math]p[/math] you can use it.

[Anonymous No.14557474]

>>14557473
No actually I looked back at your question and I was in fact stupid in my second post, please ignore it. First post was right.

[Anonymous No.14557581]

>>14556582
No.
[math]p \lor \not q = q \implies p[/math]
You take the contrapositive for [math]\not p \implies \not q[/math] and then use morbius ponens.

[Anonymous No.14557582]

How do you find reliable information? How do you access your papers and research and how do you know what you can trust?

[Anonymous No.14557593]

>>14557582
scihub and uni
If the name is chinese or indian its unreliable

[Anonymous No.14557601]

>>14557593
>uni
University libraries?

[Anonymous No.14557656]

>>14552867
are you real? are you an anime autist? i struggle to understand the connection of high math knowledge, anime and 4chan

[Anonymous No.14557678]

>>14556582
This is literally just a weaker form of the disjunctive syllogism
p v r, ~p |- r
Your statement is one where r is a negation of a statement (r = ~q).
So you don't need more than the disjunctive syllogism.

[Anonymous No.14557727]

>>14557469
>>14557473
>>14557474
>>14557581
>>14557678

Ty so much anons, this was driving me crazy and i couldn't find any information online.

>>14557469
I would be supremely greatful anon if you could show me how to use modus ponens. I am struggling to understand how to fully use logical equivalencies to manipulate rules of inference and statements in general.

>>14557581
how come you cant write it as ~p -> ~q? i was thinking if you can do this and that you have ~p as true, then you could do modus ponens by subbing in ~p = u, ~q = t and then you have
u -> t
u
therefore t.

And for the disjunctive syllogism is u = p, t = ~q so we have
u v t
~u
therefore t.

So this isnt allowed?

>>14557678
Ty for stating it like that anon, i was trying to figure out how these rules of inference are all related.

Does that mean then that you could start with disjunctive syllogism and derive modus ponens or modus tollens depending on the premises?


I just want to say you anons will never know how much i appreciate your help and wisdom, bless you.

[Anonymous No.14557777]

>>14556790
thanks anon, but we didn't study linearisation and all that stuff so I guess the only answer that I can submit is just a = x

[Anonymous No.14557832]

If i have p->(q v r) and i know q is false, how do i turn ~q into ~(q v r)?

Especially if i dont know if r is true or false.

And the same for p-> (q & r) when i know q is false. i need to do ~(q&r) but i dont know if r is true or false

[Anonymous No.14557848]

>>14557832
sorry nevermind the first part i worded that wrong.

what i actually want is:
(~p or ~q) -> (r & s) premise
~r premise
p conclusion

and i did
(p & q) v (r & s)
and i want to use ~r with disjunctive syllogism to show (p&q) and then p

but how do i go from ~r to ~(r&s)?

[Anonymous No.14558044]

>>14557777
In practical terms, a point is an equilibrium point if the derivative is zero, and an equilibrium point is stable if the second derivative has negative real part. So x=a is stable and x=±i√3 are unstable.

The rest was just an attempt at explaining why an equilibrium point is stable or unstable.

[Anonymous No.14558082]

Would you care to paraphrase / give me a clue what is happening here?
This is my first introduction to whatever this is.

>Source
https://arxiv.org/pdf/2005.07513.pdf

[Anonymous No.14558659]

>>14541669
It depends on the dimension of the vectors.
But you can work via the universal property of the tensor product, choose a basis (have fun doing so in uncountable dimension) and get down with kronecker-delta einstein degenerated symbols

[Anonymous No.14558977]

>>14557656
>are you real? are you an anime autist?
I'm not autistic.
>high math knowledge
We could teach first semester undergrads about orientations, we just don't. It's not really "high maths knowledge".

[Anonymous No.14559062]

>>14558977
>I'm not autistic.
theres nothing wrong with being autistic bro
cute flan <3

[Anonymous No.14559065]

>>14536214
can someone please help me interpret this chart:

Let's look at relapsed/refractory AML: 7 in the control group, 17 in the experimental. the P value is = .11

What does this mean? Since the p value is greater than 0.5 it means the result is not significant... Does this mean that the groups there is no difference and does not affect my experiment? Or does it mean that there is a difference and that it does affect my experiment ? What does a p value of .11 mean for this baseline characteristic?

[Anonymous No.14559487]

How do you even study biology (for personal knowledge)? Do you just memorize stuff? I've gotten interested in plants recently not sure how to go about it.

[Anonymous No.14559830]

>>14557727
You could use modus ponens here, if what you had was [math]\lnot \lnot p \lor q, ~ \lnot p[/math].
So how do you turn that p inside the or into an [math]\lnot \lnot p[/math]?
You do this by first showing that [math]\frac{p}{\lnot \lnot p \lor q}[/math] and [math]\frac{q}{\lnot \lnot p \lor q}[/math]. Note that the second one is just disjunction introduction and the first one is double negation introduction followed by disjunction introduction.
Then you can use disjuncition elimination on [math]p \lor q[/math] and the two derivations we just made and you have [math]\frac{q}{\lnot \lnot p \lor q}[/math].
Now you can use modus ponens.

[Anonymous No.14559833]

>>14557727
You could use modus ponens here, if what you had was [math]\lnot \lnot p \lor q, ~ \lnot p[/math].
So how do you turn that p inside the or into an [math]\lnot \lnot p[/math]?
You do this by first showing that [math]\frac{p}{\lnot \lnot p \lor q}[/math] and [math]\frac{q}{\lnot \lnot p \lor q}[/math]. Note that the second one is just disjunction introduction and the first one is double negation introduction followed by disjunction introduction.
Then you can use disjuncition elimination on [math]p \lor q[/math] and the two derivations we just made and you have [math]\lnot \lnot p \lor q, ~ \lnot p[/math].
Now you can use modus ponens.

[Anonymous No.14559916]

>>14559833
ty anon that's really cool i appreciate your explanation