478 reputation
29
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age 31
visits member for 2 years, 9 months
seen Sep 2 at 17:20

Sep
30
awarded  Explainer
Jan
19
awarded  Yearling
Jun
26
asked Weyl group of a restricted root system
Mar
16
awarded  Revival
Jan
19
awarded  Yearling
Sep
1
comment Siegel's theorem
I'm not sure what means the case $n\to\infty$. However, I don't know more references.
Aug
28
comment Siegel's theorem
See Cassels' book (Rational quadratic forms) in the appendix, and Kitaoka's book (Arithmetic of quadratic forms) in Section 6.8.
Aug
25
revised Pullback of differential form on the double covering
improved formatting
Aug
25
suggested suggested edit on Pullback of differential form on the double covering
Aug
25
revised about the differentiability : the general case
added 140 characters in body
Aug
25
answered about the differentiability : the general case
Aug
25
comment about the differentiability : the general case
The definition of differentiable functions is not correct. The mistake is in the hypothesis "if the partial derivatives of f existi at $x_0$". See en.wikipedia.org/wiki/Differentiable_function
Aug
25
comment about the differentiability : the general case
The elements $f(a,b)$ and $f(a_0,b_0)$ are already vectors.
Mar
8
answered If A is a finite abelian p-group, then Aut(A) acts transitively on the elements of highest order.
Mar
6
answered Unions and intersections of algebraic varieties
Feb
1
comment Image of a map in the complex plane
Try to find out the image of the vertical lines $\{(x_0,y) : y>0\}$ for each $x_0\in(-\pi/2,\pi/2)$. I remember something nice was obtained.
Jan
31
comment Simplify _Elementary Calculus_ section 1.6 problem 25 (incorrect transcription)
What is the meaning of $st(c)=7$?
Jan
30
comment Harmonic conjugate
Maybe the problem is to find an analytic function $F(z)$ with real part $g(z)=g(x,y)$, with an other condition like $F(0)=g(0)$. However, you should rewrite it if you want an answer.
Jan
30
comment Sum of n squares $(x_1^2+x_2^2 + \dots + x_n^2)^2 (y_1^2+y_2^2 + \dots + y_n^2) = z_1^2+z_2^2 + \dots + z_n^2$
Is there a square wrong on $x_1^2+\dots+x_5^2$ in the title and the first equation?
Jan
30
revised Union of dense intervals
I added $ characters