QTDDTOT—Questions that don't deserve their own thread

DO you have something good for Number theory + Abstract Algebra + Linear Algebra?

I think Landau's Foundations of Analysis is considered a number theory book.

For linear algebra and abstract algebra I can only recommend the standard texts.
Axler - Linear Algebra Done Right
Artin - Algebra

Asking for a number theory text is a little broad. Are you looking for basic elementary number theory? As for the others, I would recommend Axler and then Artin. Artin has a couple of chapters that form a good intro to algebraic number theory.

Thanks!

>Are you looking for basic elementary number theory?

Yep. Soemthing which introduces me into the cryptography and the concepts of number theory on a beginner level.

Thanks as well

My advice may be shitty at its best, but just keep going at it and support yourseld with all the resources you can (books, videos on youtube, local math students or teachers, internet forums for learners, etc.) and don't give up.

If it's your first time reading into "formal" mathematics then understand that what you are going through is 100% natural. Once you wrap your head around the logical language you're ready to start (I've still hit many brick walls since Calc, but it's always the same thing; some stuff is gonna be new, some old, some tough, but you just keep going at it).

Also, Spivak is an incredible book for redreshing your memory and flexing your math muscles with excercises, but it is definetely not recommended for beginners (I personally believe it's the worst place to start, but it should be a goal to go through chapters you've already read elsewhere and go through as many excercises as possible; you will notice how you have matured if you confront that book once in a while).

The Apostol is a great book for starters IMO, but another user recommended other good ones. I'd also recommend Mathematical Analysis by Hasser. Godspeed, user

Is it true that if you were hypothetically able to manipulate the structure of atoms you could create anything from anything?

Sure. If you could do it fast enough.

Ah. So I'm no expert in cryptography, but you'll probably just want a light exposure to group theory and then find some dedicated cryptography resources. Basic cryptography shouldn't need any number theory beyond modular arithmetic and some facts like Fermat's little theorem, which are all facts about groups.

You will laugh or be pity me but I've never worked with a book outside of school. All my classes so far in University I passed with the lecture + homework/exercises.

So I don't know if it's the better jump to start off with Groups or Number Theory

Ok I know this is probably a very stupid question but whatever.
>I'm not trying to get an exact fucking thing here, I'm just looking for a very general idea of what happens to sate my curiosity.

Say Red and Blue are two electromagnetic waves, either radio or microwave, traveling down wave guides.

What exactly comes out? (green)

Do the waves outright combine somehow?
Do they overlap each other, retaining their own wave lengths, power, wavelengths and frequencies?
Do they just basically ignore each other like two flashlights crossing beams?

If they do just overlap, what is the measured effect of the "green" coming out?
Is it a combination of the energy of both waves but at two different frequencies?

Just trying to get a general idea of how electromagnetic waves interact.

Different guy here. I know this is going to sound dumb and lazy but I've been through a lot of real analysis material (started with lazily going through a youtube lecture series) and all of the concepts I've seen are intuitive to me, yet when faced with a homework question I feel clueless. Haven't done proofs since a discrete math course for CS. I bought a book I hoped would help me (Foundations of Mathematics by Stewart & Tall) and I'm being bored out of my skull going over decimal expansions and construction of reals again while not feeling much more prepared for the work, which is seriously killing my motivation to go through it. Do your suggestions change at all given that? Otherwise, I'll check out Landau since you suggested it helped you. Really want to get to complex analysis, suppose I need to work on my impatience.

I've been self teaching maths for a while since I didn't pay attention in school, and I'm still confused about one thing, which I wasn't until now, but I guess a brain fart had to happen sooner or later. Pic related

Correct your definition: a/b = c/d iff ad = bc.

[math]a/b=ab^{-1}[/math]
[math]\frac{2a}{2b}=2a(2b)^{-1}=2a2^{-1}b^{-1}=a22^{-1}b^{-1}=a1b^{-1}=ab^{-1}[/math]

Okay so a fraction is the ratio (result of division) r of two numbers a,b. So we have [math]r= \frac{a}{b} [/math]. Here r,a,b are variables they can be any number but b!=0. e.g. a=10, b =5 then r = 2. Two fractions are equal if their r is the same i.e. the numerand diveded by the denominator. So knowing how division works we know [math] r \cdot b = a [/math]. Now if we multiply both sides by a number c ( = 3) we get [math] r \cdot (cb) = ca [/math]. Which means [math] \frac{ca}{cb} = \frac{a}{b} [/math]. In the example, we have [math] 2*5 = 10 [\math] and [math] 2*5*3 = 10 * 3 [/math], so [math] 2*15 =30 [\math] and finally we have [math] \frac{10}{5} = \frac{30}{15} [\math]. Hope you see why multiplying works and other things don't such as adding the same number, exponentiating to the third power etc.

Okay so a fraction is the ratio (result of division) r of two numbers a,b. So we have r=ab. Here r,a,b are variables they can be any number but b!=0. e.g. a=10, b =5 then r = 2. Two fractions are equal if their r is the same i.e. the numerand diveded by the denominator. So knowing how division works we know r⋅b=a. Now if we multiply both sides by a number c ( = 3) we get r⋅(cb)=ca. Which means cacb=ab. In the example, we have [math]2\cdot5=10[\math]and[math]2\cdot 5\cdot3=10\cdot3[/math], so [math] 2\cdot15 =30 [\math] and finally we have [math] \frac{10}{5} = \frac{30}{15} [\math]. Hope you see why multiplying works and other things don't such as adding the same number, exponentiating to the third power etc.

Landau is a long book full of extremely boring proofs. Especially if you've finished constructing reals (You talk about decimal expansions, are those the real number construction you're talking about?)
I was completely fresh to proofs, so it was helpful to me, but I didn't even finish the book.

For real analysis:
Rudin has great proofs, Pugh has amazing explanations for the most part
Put them together, they have a great construction of the reals via Dedekind cuts.

I forgot to mention Terrence Tao's analysis book as well. He actually works toward both real and complex analysis at the same time. Great book, a little wordy for me, so I've been skipping around.

If you haven't covered things like mean value theorem or proved the fundamental theorem of calculus, I'd suggest continuing with real analysis.

If you're moving into complex analysis, the books I'm probably gonna go into is Bak, Tao, and daddy Rudin.

Also > all of the concepts I've seen are intuitive to me, yet when faced with a homework question I feel clueless.
do proofs man. Get a notebook and just start proving shit.
ProofWiki is an amazing place to go when you get stuck.

Easiest to understand, thanks.

Can anyone help me out with this?
How's solid state (or any single-phase state) fixed with just 2 of these properties? For example, if I pick a point in the Solid region, by increasing specific volume, eventually I'll be over the solid - vapor region.
In fact, what happen if I pick a point that's over the solid - vapor region, but not touching that area?

Having trouble finishing this (taken from IMO 2005):
In a mathematical competition, in which 6 problems were posed to the participants, every two of these problems were solved by more than 2/5 of the contestants. Moreover, no contestant solved all the 6 problems. Show that there are at least 2 contestants who solved exactly 5 problems each.

I'm sorry for such a basic request, but I thought you folks would be more likely to have acces than /wsr/.

If anyone could share the texts of these articles I would be most appreciative. i don't have WoS access currently.

Ratnam KV. Effect of sexual practices on T cell subsets and delayed hypersensitivity in transsexuals and female sex workers. Int J STD AIDS 1994;5:257–61.

Richards JM, Bedford JM, Witkin SS. Rectal insemination modifies immune responses in rabbits. Science 1984;224:390–2.

Thanks for your time.

sci-hub.bz/
just plug in the website hosting the article

Thank you, that worked just fine. Hadn't heard of this.

> Just trying to get a general idea of how electromagnetic waves interact.
They don't interact.

Is a graduate degree in chemical engineering worthwhile? I don't want to sit around in a factory in the middle of nowhere staring at excel sheets all day.

> every two
In English?

Not sure about chemical engineering, but for most engineering a masters or mba is nice.
A PhD in engineering is for people who want to go into academia.

there's solutions to all of these online

so unless you have a partial solution you actually need help finishing there's not much point in asking here

>They don't
not other person, but then how do different colors of lights add to create new colors? Are they actually undergoing a change or am I just perceiving a change that has not actually occurred?

My little sister's going to Chemistry soon -- it's been a while since I've had it, so I don't really remember what I did to prepare for it. What do you guys recommend she read up and study on during her summer? I need to occupy her with something or I'll go crazy.

Hey guys, questions on Titor from years ago. The more i follow the news the more i realize the events are coming to pass that Titor spoke of years ago. The divergence seems like a very possible explanation as to why these events are happening now as apposed to Titor's original dates.

Anyone out there feel the same?

Our current technology is far more advanced than it was a decade or so ago. So i wonder whether time travel is an actual thing that could happen now?

was reading about Titor again lately as current events occur. I feel like his coming here and the people's hysterics pushed the events from the original dates to the future (now). I don't have anything to add but I do feel the same. time travel is always interesting.

Nice to know someone else feels the same, just wanted to let people know this stuff is very plausible. And to read up on what could happen.

> how do different colors of lights add to create new colors?
They don't. It's essentially an optical illusion.

> am I just perceiving a change that has not actually occurred?
Colour perception is fundamentally a property of the retina. This contains three types of sensory neurons ("cones") each of which is sensitive to a different portion of the spectrum (centred roughly on red, green and blue).

Pure yellow light (~580 nm wavelength) stimulates the red and green cones to roughly the same extent. Consequently, a mixture of pure red and pure green light is visually indistinguishable from pure yellow light to the human eye.

However, various physical processes can distinguish them. E.g. passing red+green light through a prism will split it into red and green, while yellow light will go in yellow and come out yellow. Shining yellow light on a dye which only reflects yellow or through a filter which only admits yellow will have a significantly different result than doing the same with a red+green mixture.

66 years from the Wright brothers to footprints on the moon. Has aerospace progress really slowed?
ISS and Pluto flyby is cool but shouldn't we doing better? Thoughts?

Why does my body signal I'm not thirsty/hungry immediately after I've drank water/eaten food even though I haven't digested it yet?
Is my brain lying to me?
Is it just to quickly inform me that "food in throat when stomach hurt = good" as if I didn't know that already?

count the number of years since prints on the moon to incredibly hd (like 8k by 8k) photos of the furthest totally-a-planet, I think so

> shouldn't we doing better?
Such as? Sending stuff into space is fairly expensive and, aside from satellites, doesn't have much commercial potential in the near or medium term.

especially compared to airflight which is super profitable.
Hey, why don't we have supersonic air travel yet? wtf happened?

Is there any reason to believe hell exists?

> Hey, why don't we have supersonic air travel yet? wtf happened?
We had it. It was never profitable overall, and only marginally profitable (i.e. ignoring sunk costs) for the very top end (less than 0.1%) of the market.

Ultimately that segment turned out to be too small to sustain the fixed overheads of the maintenance operation. Air France decided to terminate their Concorde operations which effectively forced BA to do likewise (otherwise they'd have had to pay the entire cost of the maintenance program rather than just half).

Since then, fuel hasn't gotten significantly cheaper, noise regulations haven't been weakened, demand for really fast long-haul flights hasn't increased (short-haul being dominated by getting to, from and through the airport), and the laws of physics haven't changed. So there's no reason to believe that another attempt would fare any better.

What happens to the body during exercise that is so good for people?
What are the exact processes and results of those processes, and/or what longer-term growth or changes does it stimulate?

It's so difficult to find good non-popsci resources on this even in an nih search. Most things are pretty non-specific and just say lower blood pressure and even helps fight cancer without any specifics.

isn't this pasta? i swear i've seen this before

A totally pop-sci explanation is that in rips and then repairs muscle with thicker and stronger materials (much like the body does for bone and blood)

I think it matters if you're talking about aerobic and aerobic exercise?

I should have been more specific, I meant aerobic in general and cardio specifically, I'm somewhat familiar with anaerobic exercise for muscle development.

No, just so incredulously ignorant that my question probably looks something like pasta.

Like nuclear transmutation?

>really, it's just a question of [re]assembling the components in the correct sequence...

just call it SQT you big unstoppable autismo

How do I work through a math book effectively? How many times should I revise to not forget the knowledge? Is every exercise / prolem setr ecommended to solve?

I have a ketone. Through a 2 step mechanism involving 1)LDA and 2) molecular oxygen and Triethyl phosphite it becomes an aldol.

I assume that the first step generates an enolate, but what happens next?

Enol reacting with molecular oxygen could lead to carboxylate or peroxic acid. And there is always the possibility for aldol condensation.

I excluded the aldol condesation because that wouldn't need the oxygen, would it? but I understand jackshit about organic chemistry.

Thanks

How long do you need to work through a book? Like in average?

Is it possible that in the far off future, we will have mapped the brain. And with this we will be able to create a virus that will create zombies based on this map?

What's a curriculum that I could take to create the zombie virus?

No it wouldn't but aldol condensation would still be the side reaction in the first step. It's not the answer this question is looking for but it's always good to list all possible outcomes.

molecular biology
biochemistry

If you're a full time student, you should study at least 40 hours a week which includes the time you spend in class.

That's not his question though. Don't be such an autist user.

What if the universe is expanding because black holes are tugging on space time? Similarly objects pulled into black holes aren't destroyed because the black hole isn't pulling on objects, instead on the fabric on which these objects rest. We cannot perceive the flexing of space time because we are within it, like how looking through a distorted lens or mirror doesn't change the objects, flex in space time is similar.

Idk random thoughts.

How are you learning a subject in a real fast way?

Phase is dependant on two things, pressure and temperature. I'm not sure what you are asking exactly but if you decrease the volume the pressure will increase between the molecules inside. Increasing the volume of the solid will eventually decrease its density and intermolecular forces to where it will become a liquid or gas.

This isn't very intuitive with solids.

Does p have to be an integer in a rational number?

A rational number is a ratio of integers, i.e. both the numerator and the denominator are integers.

Thank you

>drawing non-acidc hydrogens

Thats capsaicin. Its chilli peppers

Question for code monkeys:

Just picked up programming (JavaScript), what's the difference between console.log and print?

A lot,and its not worth it since i have no way to apply it and I quickly lose interest and forget it.

basically its just a function of few enzymes,you can read up on here and take it from there.
>en.wikipedia.org/wiki/Gastric_inhibitory_polypeptide

Is the brain a muscle?
Why are they calling it "brain muscles"?

is the brain like a muscle?

Have personality tendencies toward obsession and have heavy interest in a subject.
The combination will get you through anything no mater how complicated it is,but only if YOU and only you want it and it is not a task given by someone else or is a job you have to do.

So basically green would just be red and blue overlapping each other then?

Assuming a perfect waveguide that would line them up perfectly, the measured power of green would be red+blue?

I assume this is how multi LED flashlights work right? Just more sources all channeled together?
Neat.

What are you even studying for then? Find something to research

no, the brain is not a muscle
if anyone calls it a "brain muscle," punch them
It does act kind of like a muscle, in that when parts of it aren't used, they are removed. search myelination for more on that.

>Find something to research
I cant due to limitations surrounding me.
Ive made coupe of threads about my situation and noone seems to know how to approach it,which is fine but it got me really depressed.

>couple*

>I cant due to limitations surrounding me.
?

try something else then
theres no point in studying something if all you plan to do is forget it

Is there a way to remove edges of a petersen graph to create a new graph that is connected and contains a Euler cycle?

I know the goal is to remove edges so each vertex has a degree of two, but I can't find a way to do this without the graph being disconnected. Is this possible?

pretty certain this is impossible. Anyway I could explain why this is the case or how to rationalize this?

Specific enthalpy [kj/kg] and specific work refer to the same thing is that correct anons?

oh jesus christ, you're a cringy fucklord from /x/.
abandon all that shit and you're welcome back here any time.

>Think geek

Top tier cringe shit, pic related is one of their shirts

who /didn't_do_shit_the_whole_semester_so_theyre_learning_everything_in_one_day/ here?
Going over constraint satisfaction problems, description logics, default logics, answer set programming, and nonmonotic reasoning makes my head go ouchie

>didn't_do_shit_the_whole_semester_so_theyre_learning_everything_in_one_day/
What did you do all year? shitpost?

yes

Then you should fail

so i'm trying to simulate 2D fraunhofer diffraction in MATLAB but i'm stuck on working with changing coordinates.

For example i start at point xi,eta then end at x,y.

My function is a combination of components but I don't know how to define two separate coordinates in the same function while keeping the matrix dimensions agreeable.

So the quotient ring R[x]/(x^2+1) is isomorphic to the complex field.
This is an algebraically closed field constructed from a ring.
I have a few questions regarding this:
Can every algebraically closed field be constructed from a ring or similar structure? If not, what fields have that property?
The spectrum of the above ring is equal to the whole ring (i think)
If an algebraically closed field can be realized as a quotient ring, is the above statement about the spectrum true in general?

Hey Veeky Forums,

I'm currently a student in the Southeast studying Mech Eng with a minor in sustainability. I'm interning at a nuclear station this summer and am looking at interning in the PNW next summer to try to get connections out that way so that I can get a job and move there after I graduate. Any recommendations of companies to look at? I know Boeing, I interviewed with them this summer, but unfortunately they really preferred me working at the Charleston plant rather than heading across the country

Blow it up fag

Any algebraically closed field K will contain a proper subfield F. You can then construct K by taking a quotient of the polynomial ring in some absurdly large number of variables by an ideal containing all monic irreducible polynomials over F. You can probably Google around for this.

>The spectrum of the above ring is equal to the whole ring (i think)
I'm not sure what you're trying to say here. I don't know a meaning of "ring spectrum" other than the set of prime ideals. Since R[x]/(x^2+1) is a field, there is only a single prime ideal, namely 0.