@Ste @Ale @Bal Ah, I see, I was confusing the ideal generated by $F\in R[x]$ with the subring generated by $F$. (The former includes $xF$; the latter doesn't in general. The latter is $\{1,F,F^2,\dots\}$.)
So, yeah, to deal with the ones of sufficiently high degree, find polynomials in the ideal whose leading coefficients generate the ideal of all leading coefficients. And a similar muckery deals with the ones of smaller degree.
@Abcd I believe you will need Vieta's formulas, which are not too hard to derive especially in the quadratic case. Leaky was walking you through it rather well. Think about what he was saying and review your formulas, this will make sense
@Semi I had this one fun problem in the REU last summer which related to this. So let's say you're a pirate, and the treasure map tells you the location based on the roots of a polynomial. Because it's ripped, you only see the first three terms, $x^{17} + 5x^{16} + 13x^{15}$. Show that not all the roots are real
Similarly: 3) If you want to get the constant term, you need to take r_k from all the linear factors; putting these together gives the constant term as $(-r_1)(-r_2)\cdots(-r_n)$.
So the constant term tells you about the product of the roots.
I'm still trying to see, next year there won't likely be much room, and also my experience level will be a bit low. 4th year, I could very much see this happening
I've considered asking either one of the PDE people about doing calc of variations (probably Souganidis, already took a class with him and am about to do another). Another thing I have in mind is to see after algebra next year, I'll possibly ask maybe Emerton then if I find some topic in that which would be suitable to a good reading course @Paul
In big words. BERNOULI'S
$$y'+\frac{y}{t}=t \ln t$$
Integrating Factor: $e^{\int\frac{dt}{t}}=t$
$$\int d(yt)=\int t^2\ln t.dt+C $$
To solve $\int t^2 \ln t$, take $t=e^x$ and proceed.
This shall give your answer
$$\int e^{2x}.x=\frac{1}{2}(x.e^{2x}-e^{2x})$$
Suppose f is a zero divisor. Choose polynomial $g = b_0 + b_1x + \ldots + b_mx^m$ of least degree m such that $fg = 0 \implies \Sigma_{k \geq 0} \Sigma_{i + j = k} a_i b_j x^k = 0$.
From the formula of multiplication of two polynomials we must have $a_nb_m = 0 \implies a_n g = 0$ (Because $a_n g$...
@Daminark Do they not have any interesting algebra classes you can take (maybe a grad class or topics class?). I mentored someone for a little bit ind a DRP, stopped after a couple weeks though
Oh there are a lot. There's grad algebra, which I hope to do, and then there are undergrad classes in rep theory, algebraic geometry, commutative algebra, algebraic curves, algebraic number theory, etc
Algebraic geometry is a fall class, and it requires a year of analysis and 2 quarters of algebra only. They do recommend you do third quarter algebra and topology/complex analysis as well
Commutative algebra is a winter class which requires the full year of algebra
Hi guys. Is there any mable expert here tonight? I'm trying to subsitute some values into an equation, but for some odd reason it doesn't seem to wiork ?!
I dunno, they should probably just swap the two quarter and make commutative algebra a prereq or something, but I guess. Whatever the case, the first priority is grad algebra, it'll subsume the others anyway
Suppose f is a zero divisor. Choose polynomial $g = b_0 + b_1x + \ldots + b_mx^m$ of least degree m such that $fg = 0 \implies \Sigma_{k \geq 0} \Sigma_{i + j = k} a_i b_j x^k = 0$.
From the formula of multiplication of two polynomials we must have $a_nb_m = 0 \implies a_n g = 0$ (Because $a_n g$...
@Danu: I saw your question earlier. I've never worked this out, but I can tell you it is true for the quadric surface in $\Bbb P^3$. This is the Veronese embedding of $\Bbb P^1\times\Bbb P^1$ and the embedding is an isometry. So you can check it easily in that case. I'll ponder more later.
@TedShifrin btw I decided to write everything in latex. My solutions for books and also my notes and stuff. I solved first 3 chapters half of the questions for Michael atiyah, but I lost the notebook.
@DanielGuldbergAaes Even though the error doesn't say "you forgot a comma", it helps you narrow down the problem. In thise case, it tells you that there's something wrong with the input {false,x = 4-t}. x = 4-t is indeed what you want there, but "false" isn't - you want y = ... and z = ... . Hence something is wrong with those input thingies
@Ted but they are! You just need sufficient exposure to them and you'll see why they are great. In the first few years it might be hard to see, but give it time
One cataclysm after another. More religious bigotry this morning and he thinks he's going to be the one to broker peace in the Middle East — "since it isn't that complicated"
Indeed I suspect that the metric given as a sub space of the complex projective space is itself homogeneous. I don't know how to check KE from there, but it seems plausible.
@MikeM @Danu: But it isn't a priori obvious that the induced Kähler metric as it sits in $\Bbb P^N$ is that one.
We just said the same thing. I guess one needs to check equivariance. I'll think about it.
Annoying — I forgot to close some apps on my phone last evening and the battery ran down to 0. So I can't go run errands until it charges up enough, cuz I need it somewhere along the errands.
Third-world problem, I realize. Life was so much easier when I was 20 yrs behind the times.
That's fair, I guess this is the first time that I've actually been aware of politics so my entire view is Trumpian.
As for healthcare, I haven't thought much about it. I know in Texas everyone hates it because of the mandate and because most doctors there reject it anyway, but I've also heard that it very much was a step in the right direction
The second one is because you can just think about it as R^2015. It comes out through bolzano/heine borel. For the third take the sequence (1,0,0....) (1,1/2,0,0...)(1,1/2,1/3,0,0,0....) which converges to (1,1/2,1/3,.....1/n,1/(n+1),....) etc. So it is not compact.
@TedShifrin Could you elaborate? This question theoretically should only need the sequential definition of compactness, Bolzano-Weierstrass, topological invariance of sequential compactness.
You should be able to write down a bare-hands argument that a sequence has a convergent subsequence. You probably will need to use the Cantor diagonal argument somewhere.
@Gridley: Yeah, so how do we prove a sequence of points in $[0,1]^2$ always has a convergent subsequence? If you figure this out, it gives you the idea.
Oh, Schoen-Yau's theorem. I've never seen the proof, @Eric.
yeah I mean, I've found it to be an acceptable pace for me, but my classes other than the ones with neves have basically been prior knowledge for me, so haven't had to work much outside of geometry
Does anyone have an idea why Wolfram Alpha evaluates this limit at 0http://m.wolframalpha.com/input/?i=limit+as+n+goes+to+infinity+of+sum+i+from+1+to+n+of+%28%285%5En-1%29%2F%28n*n%21%29%29&x=0&y=0
Is the image of a connected component under a continuous map a connected component? Clearly the image will be connected, but I am having trouble showing that it will be a component.
@Eric So we've been lagging the syllabus big time. As it stands we've defined intersection number today, so next class we're gonna define degree in general, and then get into finding degree through differential forms. After we get through that stuff we'll be done with the technical theorems, and then move on to applications like Poincare-Hopf
@AlessandroCodenotti The part I am referring to is this: "So the connected component of y must be a translate (by fy) of the connected component of the origin."