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Nov
1
revised Functions space of discrete space: how does taking quotients lead to noncommutativity?
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Nov
1
accepted Functions space of discrete space: how does taking quotients lead to noncommutativity?
Nov
1
asked Functions space of discrete space: how does taking quotients lead to noncommutativity?
Oct
21
revised Euler-Lagrange equation problem
added 132 characters in body
Oct
21
revised Euler-Lagrange equation problem
added 132 characters in body
Oct
21
answered Euler-Lagrange equation problem
Oct
17
revised Finding $\lim_{n \to \infty} \frac{\sqrt{n!}}{2^n}$
changed in title $x$ into $n$
Oct
17
suggested approved edit on Finding $\lim_{n \to \infty} \frac{\sqrt{n!}}{2^n}$
Oct
17
comment Topological structure of a quotient of ${\rm{SU}}(2)\times{\rm{SU}}(2)$
Not an answer, but synonyms: $\mathbb{S}^3\times \mathbb{S}^3/\mathbb{Z}_2$ is the double cover, Spin$(4)$, of SO(4).
Oct
16
comment Christoffel symbols in Differential geometry iff proof
But Christoffel symbols are objects (non-tensors) with three indices (unless you contract two of them). I.e. $$\Gamma^\alpha_{\beta\gamma}=\frac{1}{2}g^{\alpha\mu}(g_{\mu \beta,\gamma}+g_{\mu \gamma,\beta}-g_{\beta\gamma,\mu}).$$
Oct
14
suggested rejected edit on How to show that $\frac{1}{\tan(x/2)}=2 \sum_{j=1}^{\infty}\sin(jx)$ in Cesàro way/sense?
Oct
14
comment Christoffel symbols in Differential geometry iff proof
Hi! I'd like to know what does $H$ mean? where are the Christoffel symbols here?
Oct
14
comment $4 \times 4$ matrix and its inverse. Is my method ok?
I'm sure there are more modern references, but in Jackson's book on Classical Electrodynamics (chapters 11 and 12) you can find a complete physical approach (I don't think special relativity should be read as math, for it is definitely not math). By definition, $\gamma$ satisfies $\gamma^2-\beta^2\gamma^2=1$, so you can set $\phi=\cosh^{-1}\gamma$ with a sign ambiguity to be fixed by $\sinh \phi=\beta\gamma$. Then $\gamma^2-\beta^2\gamma^2=1=\cosh^2(\phi)-\sinh^2(\phi)$.
Oct
12
awarded  Promoter
Oct
12
answered $4 \times 4$ matrix and its inverse. Is my method ok?
Sep
17
awarded  Autobiographer
Aug
11
awarded  Teacher
Jun
24
asked Dixmier-Douady class: computations
Jun
23
comment Compact resolvent VS certain boundedness condition
I see. However, one doesn't have control on the boundedness of the elements in $A$. Anyway, very helpful answer.
Jun
23
accepted Compact resolvent VS certain boundedness condition