@TedShifrin yeah not been doing that great thie last 10 days plus a couple midterms and a few assinments. Making it difficult aced both the midterms i think though. Might have to ask for an exstension on one of my assinments due friday. Next dosage increase in 5 days hopefully be better then!
Hmm, I don't think they intersect at all, do they? The intersection would need to only involve $3$ of the elements, which makes a double transposition impossible.
It's easy to see abstractly. If P and Q are 2-Sylows which intersect then N_G(P \cap Q) contains both P and Q since they are both abelian, so has to have order more than 4. The only possibility is 12 (can't be 20, index is 4, that'd give a left reg rep A5 -> S4 but A5 is simple).
@Fargle If you are referring to Aluffi's Algebra Chapter 0, a similar book is MacLane and Birkhoff's Algebra, which also has lots of categories. It's in the AMS Chelsea series.
Is it correct to say that while many say naturals, rationals, and reals, not many say complexes? If so, might it be because a complex can mean so many other things?
OK, got it @rschwieb. So, when we're trying to show that $\langle\mathbb{Q},+\rangle$ is a group, we refer to integers. On the other hand, "A first course in abstract algebra" gives $\langle\mathbb{Z},+\rangle$ as an example to group (abelian). We accept it as a group and don't show anything.
Counting, - Whole, whole Naturals, natural Integers, integral Rationals, rational Irrationals, irrational Reals, real Complex, complex (anything else is too rare to be of significance)
@AbdullahUYU Well, I don't know how you define the integers, but quite often you define it as a list of axioms stating that it has the properties of a group.
@AbdullahUYU I don't know what you mean about $(\mathbb Q,+)$ "referring to the integers." It is true that the addition in $\mathbb Q$ is defined in terms of addition and multiplication in $\mathbb Z$, if that's what you mean.
I also learnt that the terms integer part / fraction part or integral part / fractional part are all used in the literature when I posted an answer to an English question long ago.
The students will understand $v \in \mathbb{R}^n$, and $v^T$ however I would also like to formally denote then space for $v^T$ and it feels like, I should not simply write $\mathbb{R}^n$
@WillHunting Lol. I've been a bit swamped with school, but I do think I have the very first sentence figured out. I'm trying to see what I can derive from that. I feel like I need a more thorough understanding of the properties/axioms of functions and why they are.
@WillHunting I'm using a few different sources at the moment.
Let $V$ be a finite dimensional vector space over a field $k$ with basis $B=\{v_i\}$. And let $V^*$ be its dual space with basis $B^*=\{\beta_i\}$, with $\beta_j(b_k)=\delta_{kj}$.
Show that $V^*$ is isomorphic with $V$.
We haven't been shown that two vector spaces are isomorphic if the have t...
@WillHunting It was very surface though, at least compared to set-theoretic definitions. We learned domain/co-domain and graphing, not much beyond that.
@WillHunting It seems like I always almost have the answer, but then I start overthinking.
@DavidCoffron I don't like people excessively downvoting and closevoting questions on this site myself, but if you want to know why they did it, you can read the explanation in the closing box.
@CaptainAmerica16 In high school, a function will yield a graph, which can be thought of as a set of ordered pairs. Now formally, we just define the function to be this set of ordered pairs. Hope that gives you a good idea.
@CaptainAmerica16 Well, some authors use range to mean codomain and image to mean range. Like I said, different books will use the same word to mean different things or different words to mean the same things. A cat can be defined as a dog, and a dog can be defined as a cat.
@DavidCoffron Read the words in smaller font. There are lots of words in that box.
@DavidCoffron Good, then you have done your best. Now you can wait patiently for the question to be reopened, but I don't know if or when. I am frustrated with the current state of things as well.
@WillHunting Is it at all commonplace to ask on the meta site for an additional explanation. I know some sites encourage this and some sites forbid it.
@DavidCoffron You can, but I don't know the reaction. I don't even want to comment too much because some users may think I am attacking them if I do so. I only replied to you because I wanted to help you.
@WillHunting Sounds like a healthy condition for the site... I'll try my luck perusing the meta and ask a question if it seems like others have in the past
@CaptainAmerica16 A word about the subset notation. Some people use the notation without an extra line at the bottom to mean subset, but some use that to mean proper subset.
@WillHunting I was just reading a Math.SE post on that yesterday. It threw me off a bit when I looking at examples from different sources. From now on I just assume it means subset unless otherwise stated.
@WillHunting True. When it comes to math, I need to get better at utilizing exactly what's presented to me. Not necessarily with tests, but with problems in general. I've found I overthink things to the point where I miss obvious details.
@WillHunting You point about functions a few comments ago is very helpful. That's the thought pattern I'm following. I'm just trying to find a way to express it.
@CaptainAmerica16 Yes, just be careful if you have the tendency to overthink. Don't let that lead to anxiety problems or mental illnesses.
@CaptainAmerica16 Yes, once you truly understand some things, you can use a few words to express the idea beautifully. That is one test of understanding.
@WillHunting Lol, not to get too deep, but I've been doing a lot better with "overthinking" this year. I used to have bad tics, but now it's only when I'm stressed. Thanks for the advice.
@Ultradark there's an easier way: do a linear substitution: make a linear substitution $u=\frac{x}{2}+\frac{1}{2}$ do you know the integral $\int_{-1}^{1}\sqrt{1-x^2}\mathrm{d}x$? this has a clear geometric interpretation
$\sqrt{x}\sqrt{1-x}=\sqrt{x-x^2}$, then it's just basically completing the square and multiplying by a constant to get it into the form $a^2-ax^2$ (in this case with $a=\frac{1}{4}$)
@Ultradark yes, you can compute $\int_{-1}^{1}\sqrt{1-x^2}\mathrm{d}x$ with an arcsin, but it's really just the area of a half-disk, one learns how to compute that before you learn integrals
@CaptainAmerica16 Of course, if one set is a subset of the other, they may not be equal, because the second set might contain elements the first one does not.
@WillHunting That's perfect. Not saying I have it completely figured out, but I think I'm finally on the right track. It literally all stemmed from your comment earlier.
Why is Math SE down? What kind of maintenance are they doing?
@MatheinBoulomenos True. What is less clear is what integrands and what integration region will give a geometrically straightforward integral
I don't think there is a systematic relation between the two
More rigorously, Define the class of all geometric integrals as the ordered pair $(f,\mathcal{D})$ such that $\int_{\mathcal{D}} f d\mu$ is computable without series methods
Systolic geometry is a branch of differential geometry, a field within mathematics, studying problems such as the relationship between the area inside a closed curve C, and the length or perimeter of C. Since the area A may be small while the length l is large, when C looks elongated, the relationship can only take the form of an inequality. What is more, such an inequality would be an upper bound for A: there is no interesting lower bound just in terms of the length.
Mikhail Gromov once voiced the opinion that the isoperimetric inequality was known already to the Ancient Greeks. The mythological...
I hope this systolic geometry has nothing to do with that riemannian hypothesis question. A month full of chat conversations that does not line up is enough for my poor brain
repetition is sooooooooooooooooooooooooooooooo boring
quotienting certainly means that make the group/object smaller by grouping different things together. For example in $\Bbb Z/2\Bbb Z$ we group all even numbers and all odd numbers together, thus dividing the group into two objects
@KasmirKhaan intuition does not always come right away, sometimes you need to work with something as a purely formal thing and you get some intuition later with experience (at least that's how it is for me)
I am very strange, it takes a while to understand what I am doing, because as it turns out, according to artists, I actually think more like an artist than a scientist
@KasmirKhaan There is a short bit about free groups and presentations in home.math.au.dk/sorsted/persp_algebra.pdf which I referred to when I went over it in lectures
@KasmirKhaan Note that that book defines rings without 1, while other books may define rings to include 1. And that book actually covers up to first year graduate level algebra as well. I like how it proves the cubic and quartic formulas when you do Galois theory.
I'm looking for a result in functional analysis that says if the difference of two functions is small in norm, then their integrals are also close. Does anyone know which theorem I'm talking about?
@CaptainAmerica16 I think that should be a fairly short proof. I think you could do it in less than 15 lines! You can always be more thorough with a proof and write out every little detail to understand it completely. That helped me when I took an intro proofs class. But if you really understand, you can make the proof pretty succinct and concise.
@Ultradark Ah, ok! I'm still trying to figure out what is necessary to define and what isn't, but what I have so far seems to be lining up with what you described. I'm finally making progress!
In particular, I'm considering approximating a step function with polynomials.
I'm looking for the formal statement that says "since these two functions are close a.e., then they should have similar integrals." It sounds like something that I learned in a functional analysis class, but that isn't important enough to have a name. I was looking in Reed and Simon, but couldn't find it.
Let K be a finite extension of F and $L_1, L_2$ are intermediate extensions. How can we show that there isa basis of $L_1L_2$ over $L_1$ that consists of elements of $L_2$ ? Could you give me a hint?