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Jun
22
awarded  Enlightened
Jun
22
answered Presheaf that do not satisfy: If $\{U_i\}$ is an open cover of $U \subseteq X$ and $s \in \mathcal{F}(U)$, then $s=0$ iff $s|_{U_i}=0$ $\forall i$
Jun
22
comment Presheaf that do not satisfy: If $\{U_i\}$ is an open cover of $U \subseteq X$ and $s \in \mathcal{F}(U)$, then $s=0$ iff $s|_{U_i}=0$ $\forall i$
As you mention $0$, I assume you only consider (pre-)sheaves that are at least abelian-group-valued (i.e., not set-valued)?
Jun
22
awarded  Nice Answer
Jun
21
answered $C_c(X)$ is dense in $C_0(X)$
Jun
21
answered If $G$ is a group and $g \in G$ has order $n_{1} n_{2}$, $1=\gcd(n_{1},n_{2})$, then there exists…
Jun
21
answered Fair 5-sided die
Jun
21
revised Conditionally convergent - limit of series'
added 3 characters in body
Jun
21
comment Conditionally convergent - limit of series'
"Suppose $a_n<0$ for $n$ odd ..." - this is not justified
Jun
21
answered Conditionally convergent - limit of series'
Jun
21
comment If $f'$ is increasing and $f(0)=0$, then $f(x)/x$ is increasing
The fact that $f'$ is strictly increasing does not exclude that possibiity that $f''(b)=0$ for some $b$.
Jun
21
answered If $f'$ is increasing and $f(0)=0$, then $f(x)/x$ is increasing
Jun
21
comment If $f'$ is increasing and $f(0)=0$, then $f(x)/x$ is increasing
@gash You are given that $f'$ is increasing, i.e., $f''\ge 0$. To let $f''$ enter the scene, take derivative of $f'(x)x-f(x)$
Jun
21
comment Wolfram with predicates any posibility?
Why use Wolfram instead of pen an paper?
Jun
21
answered Find $\lim_{n\to \infty}\left(\frac{\log (n-1)}{\log (n)}\right)^n$ without L'Hopital's rule
Jun
21
comment Proving that between each pair of vertices there is a path length $2$ at most
You are done. Either $v=w$ and there is a path of length $0$; or $v,w$ have a common edge and there is a path of length $1$; or - as you showed - they have a common neighbour $u$ and $vuw$ is a path of length $2$.
Jun
21
comment Error in or another way of calculating $\frac{1}{2} \in \mathbb{Q}_3$
Well, $4=1+3$ so you get again that $-(1+3+3^2+3^3+\ldots)=\frac12$
Jun
21
answered Finding the right equation for alpha
Jun
21
answered The difference between $[n]^k$ and $\begin{pmatrix} [n]\\ k \\\end{pmatrix}$
Jun
21
answered Error in or another way of calculating $\frac{1}{2} \in \mathbb{Q}_3$