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Mar
22
revised convolution: how can I show that $(y*f)'(t) = (y'*f)(t) + y(0)f(t)$
deleted 85 characters in body; edited title
Mar
22
answered $\sum_n |x_n||y_n| < \infty$ for all $(x_n) \in l^3$ implies $(y_n) \in l^{3/2}$
Mar
22
comment Is there a group $G$, for every $n>0$, acts on set $\{1, 2, …, n^2\}$ with orbit of size $n$?
$[G: Stab(1)]$ is a quotient of $G$, hence smaller then $G$. And no finite number $|G|$ has $|G| \ge n$ for all $n$.
Mar
22
revised Is there a group $G$, for every $n>0$, acts on set $\{1, 2, …, n^2\}$ with orbit of size $n$?
added 49 characters in body
Mar
22
answered Is there a group $G$, for every $n>0$, acts on set $\{1, 2, …, n^2\}$ with orbit of size $n$?
Mar
22
answered Given $\Bbb N$ can you reach every infinite cardinal by performing succesive power set operations?
Mar
22
answered Showing that the operator norm is equal to the q-norm.
Mar
22
revised Show that curve has a constant torsion.
deleted 1 character in body
Mar
22
comment Show that curve has a constant torsion.
Now, but $U := \{\beta\}^\bot$ is a two-dimensional subspace. Any three vectors in $U$ must be dependent.
Mar
22
answered Show that curve has a constant torsion.
Mar
22
comment Every finite connected space is also path-connected?
If $y \in A$, $y' \in U_y$, there is a sequence for $y$, $x_0=x, \ldots, x_n = y$. But then $x_0 = x, \ldots, x_n = y, x_{n+1} = y'$ is a sequence for $y'$. If $z' \in U_z$ and $z' \in A$, say $x_0 = x, \ldots , x_n = z'$ were a sequence for $z'$, then $x_0 = x, \ldots, x_n = z', x_{n+1} = z$ were a sequence for $z$. Contradiction. Hence $z' \not\in A$.
Mar
22
answered $A$ does not reverse the sign of any vector iff $A^{T}$ does not.
Mar
22
answered Differentiation of a measure
Mar
22
reviewed Leave Open Maple - PDE substitution
Mar
22
reviewed Leave Open How can I show that the stochastic process $M_t = W_t^3 – 3t W_t$ is a martingale $\mathbb{E}[M_u|F_t]$?
Mar
22
reviewed Leave Open Laplace Transform: $g(x)=a\sin(x)+\int_0^x \sin(x-u)g(u) du$
Mar
22
reviewed Leave Open How can this improper integral be solved
Mar
22
reviewed Leave Open Division polynomial by polynomial with 2 variables
Mar
22
reviewed Close Find the closed formula for following problem.
Mar
22
reviewed No Action Needed Ring of all $\mathbb{C}$-valued continuous functions on closed interval Noetherian?