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Oct 10, 2022 16:53
I found a vector of weight $(\mu_1, \mu_2)$ but am not sure how to proceed. I know every representation of $\mathfrak{sp}_4(\mathbb{C})$ is totally reducible.
Oct 10, 2022 16:52
Let $\mu_1 >= \mu_2$ be two natural numbers. Let $S = \mathbb{C}^4$ and let $A = \mathfrak{sp}(4,\mathbb{C})$ the complex symplectic Lie algebra of $Sp(4, \mathbb{C})$. Let $V$ be an irreducible representation of $A$ of highest weight (1,1). I need to prove $S^{\otimes(\mu_1 - \mu_2)}\otimes V^{\otimes \mu_2}$ has a irreducible sub-representation of weight (mu_1, mu_2).
Jun 26, 2022 12:37
Can someone give me a hint how to compute $[M_{g} ,S^{2}]$ where $M_{g}$ is the surface of genus g and $[M_{g} ,S^{2}]$ is the set of continuous maps from $M_{g}$ to the sphere modulo (free) homotopy ? My hint is to use the Cellular Approximation theorem. I know both are CW complexes.
May 31, 2022 20:39
$L:H^{1}( \Gamma (TM) ) \subset L^{2}( \Gamma (TM)) \rightarrow L^{2}( \Gamma (T^{\ast}M \otimes T^{\ast}M)) $
May 31, 2022 20:26
Lie derivative of the metric
May 31, 2022 20:26
how can I prove $L(x)=L_{x}g$ is a closed operator?
May 8, 2022 08:52
Is the product of two chain complexes (modules over ring R) is the product level wise and boundary maps points wise?
Mar 29, 2022 21:42
This makes no sense.
Mar 29, 2022 21:40
What does it mean that the functor from Set to Grp sending a set to the free group generated by it commutes with pushouts? what do I need to show? that given a pushout (P,i,j) with i,j the pushout morphisms, we have F(i)F(j)=F(j)F(i)?
Mar 7, 2022 17:08
Sorry, I mean $\langle\nabla u,\nabla u^{T}\rangle_{L^{2}(\Omega)}\geq0$
Mar 7, 2022 17:03
with $\Omega$ bounded
Mar 7, 2022 17:03
Hi, is it true that for $u\in C_{0}^{\infty}(\Omega)$ we have $$\langle\nabla u,\nabla u^{T}\rangle\geq0$$ ? if so, how can I show it?
Jan 5, 2022 22:23
smooth vector fields
Jan 5, 2022 22:22
$\mathfrak{X} (M)$ - domain of $\mathcal{L}$
Jan 5, 2022 22:22
Is it possible to show that with such norms $\mathcal{L}: \mathfrak(M) \rightarrow \Gamma(T^2 T^\ast M)$ taking $X\mapsto \mathcal{L}_{X}g$ is closed?
Jan 5, 2022 22:15
* sup going also over all $p\in M$
Jan 5, 2022 22:15
with $\Gamma(T^2 T^\ast M)$ being the space of covariant 2-tensor fields?
Jan 5, 2022 22:13
Ok. So for $T\in \Gamma{T^2 T^\ast M}$ can I take $Sup|T(X_1,X_2)|$ going over all $|X_i|=1$ $i=1,2$ as a norm? does that makes sense?
Jan 5, 2022 22:11
Yes, ofcourse.
Jan 5, 2022 22:10
$max_p |\langle X_p , X_p\rangle_{g_p}|^{1/2}$
Jan 5, 2022 22:08
Does it makes sense to take $Sup_p \langle X_p , X_p \rangle_{g_p}$ as a norm over vector fields?
Jan 5, 2022 22:05
&g& is the metric of the Riemannian manifold
Jan 5, 2022 21:59
Hi, I am trying to prove that the operator $X\mapsto \mathcal{L}_{X}g$ is a closed operator when working on a compact manifold. I know I need to limit my domain so that I will have a Norm space into a norm space, since the space of smooth sections over a manifold is not a norm space. Is there a way to do so?
May 15, 2021 14:40
I am mainly interested in the proof of one of the sides of the lemma (I am trying to proof $dimKerD < \infty$ )
May 15, 2021 14:40
Hi, I am looking for the source of the lemma in this question : math.stackexchange.com/questions/1594788/…
May 8, 2021 13:32
If A is a d by d matrix, how can I get this inequality $$|AA^{T}A-A|\leq C(1+|A|^3)$$ with the norm being any norm on $$\mathbb{R}^{d\times d}$$ ?
May 5, 2021 21:31
Thank you @TedShifrin
May 5, 2021 21:28
Oh this is cool!
May 5, 2021 21:24
or flat surface?
May 5, 2021 21:24
Ain't that meaning that my surface is like a sphere or ... not sure what is the opposite of a sphere
May 5, 2021 21:21
Ok. So far mean curvature is not in the material. But we are half way to the course
May 5, 2021 21:19
Yeah, the boundary is measurable
May 5, 2021 21:19
Yes. Lipschitz domain
May 5, 2021 21:18
Variational calculus
May 5, 2021 21:16
I don't know why I feel this is true but I got this ichy ich that I need to be careful when saying it :P
May 5, 2021 21:15
When $$ \Omega $$ is a bounded open connected set?
May 5, 2021 21:15
Is it true to say that the volume of $$\Omega \subset \mathbb{R}^n $$ only depends on $$ \partial \Omega $$ ?
Apr 17, 2021 21:08
Can someone assist me with math.stackexchange.com/questions/1462020/… , I am stuck in the same place and can't understand the equality
Apr 17, 2021 14:26
peace out
Apr 17, 2021 14:25
Order of magnitude more useful
Apr 17, 2021 14:24
without the need to restart the browser. Really nice
Apr 17, 2021 14:24
Yes it does
Apr 17, 2021 14:18
$f$ testing chatjax
Apr 17, 2021 14:10
Yes I understand now. Thank you very much robjohn!
Apr 17, 2021 14:07
oh ok. Now I understand :D
Apr 17, 2021 14:05
Yes. If $\eta(x-y)$ increasing in $x$ then it is decreasing in $y$.
Apr 17, 2021 14:01
I don't understand why the chain rule gives this
Apr 17, 2021 13:58
Why this equality holds? I don't get it
Apr 17, 2021 13:57
No. This $\int_{\Omega}\partial_{x}^{\alpha}\eta_{\delta}(x-y)f(y)dt=(-1)^{|a|}\int_{\Omega}\partial_{y}^{\alpha}\eta(x-y)f(y)dy$
Apr 17, 2021 13:55
ok. Any better way to present the question?