Reputation
774
Next privilege 1,000 Rep.
Create new tags
Badges
4 13
Newest
 Yearling
Impact
~10k people reached

  • 0 posts edited
  • 0 helpful flags
  • 65 votes cast
Feb
15
asked If the covariant derivative vanishes
Jan
27
asked Integration over two sub manifolds
Jan
17
accepted Which initial functions can be solved by separation of variables
Jan
16
comment Which initial functions can be solved by separation of variables
Thank you very much. Your last formula is very elegant and it seems as if the function $u(x,t)$ is not differentiable in general, even not for $f,h\in C^2(0,1)$. When we assume further that $f,h$ can be extendet periodically in a $C^2$ fashion then the right hand side would be $C^2$ as well. Is this the most general assumption to guarantee the existence of a $C^2$ solution?
Jan
13
revised Which initial functions can be solved by separation of variables
added 630 characters in body; edited tags
Jan
12
asked Which initial functions can be solved by separation of variables
Jan
12
comment convergence of series in inner product space
Perfect answer! Thank you very much!
Jan
12
accepted convergence of series in inner product space
Jan
12
revised convergence of series in inner product space
added 9 characters in body
Jan
12
asked convergence of series in inner product space
Jan
12
accepted dihedral group and its generators
Dec
21
asked dihedral group and its generators
Dec
18
revised Group actions by semi-direct products of groups
deleted 295 characters in body
Dec
18
revised Group actions by semi-direct products of groups
added 217 characters in body
Dec
17
revised Group actions by semi-direct products of groups
deleted 92 characters in body
Dec
17
comment Group actions by semi-direct products of groups
I have another question: Is there some rule of thumb how to recognize which semi-direct product the author had in mind? For instance is it common to assume, or to interpret the situation as an inner semi-direct product whenever there is no group action mentioned?
Dec
17
comment Group actions by semi-direct products of groups
Thank you very much for your help Alex G. I did not even thought of this possibility. I suppose the bigger group is $K:=\lbrace x\mapsto A(x+z): A\in G, z\in\mathbb{Z}^2 \rbrace$. ( One can show $\mathbb{Z}^2$ is a normal subgroup of K). Are my calculations correct so far? But I could not figure out why $\mathbb{R}^2/K$ equals a square with side length 1/2
Dec
17
asked Group actions by semi-direct products of groups
Dec
16
comment Group of rotations of rational multiples of $\pi$
Thank you for your comment. Your first sentence does not seem to be correct. Consider the example $\frac{2}{3}\pi$ and $\frac{\pi}{3}$. The fractions are reduced and obviously the denominators are equal. But the groups are different. Am I missing something?
Dec
16
asked Group of rotations of rational multiples of $\pi$