Hagen von Eitzen
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372/400 score
 Apr7 answered An equivalence of AC Apr7 comment Are there non-surjective homeomorphisms? In other words, only itself should be in vold. Or you might ask, why homeomorphims of a space ...? Aren't all homeomorphisms defined on a space? Apr7 comment Definition of groups in a more abstract way Regarding 1, whhat do you mean with $e(1)$? This need not be a concrete category. Apr7 comment Definition of groups in a more abstract way Regarding 3, existence of two-factor products is the same as existence of finite products. $G_1\times \ldots \times G_n\cong (\ldots(G_1\times G_2)\times \ldots )\times G_n$ canonically. (The diagrams already use three-factor product $(G\times G)\times G$, in the form of repeated two-factor products, and the canonical isomorphism with $G\times(G\times G)$). Apr7 answered Inductions and proofs Apr6 answered if g'(x) tends to 0 as x tends to infinity, how to prove g(x)/x tends to 0 as well Apr6 comment Are mini-Mandelbrots known to be found in any fractals other than the Mandelbrot set itself? Depends a bit on what you accept as mini-Mandelbrot (you know even those "copies" of $M$ in $M$ itself are not exactly copies ...) Apr6 comment Show that an integral can be made as small as possible. Pick $\delta$ such that $\int_\delta^1\frac{\mu(s)}{s}\,\mathrm ds$ differes from $\int_0^1\frac{\mu(s)}{s}\,\mathrm ds$ by less than $\epsilon$? Apr6 answered Groups - identity - abstract algebra Apr6 comment Is every set a pointed set? If $A$ is a (nonempty) set, then $A$ is not a pointed set. However, if $a\in A$, then $\langle A,a\rangle$ is a pointed set. So there is little sense (not to say: no point) in talking about a set being pointed or not before you pick a point. Apr6 answered Question about open and closed sets Apr6 answered Proving that if $E, F$ are equivalence relations on $A$ and $E \subseteq F$, then there is a surjection from $A\setminus E$ to $A\setminus F$ Apr6 answered How can i solve limit. Apr5 comment arc length on circle It should read $[t,t+dt]$. Apr5 awarded Great Answer Apr5 comment What modular arithmetic theorem is being ignored here? No theorem is ignored, but there is a "non sequitur" in 1. Apr5 answered What modular arithmetic theorem is being ignored here? Apr5 comment A property of integers Did you try $a_0=81$? ;) Apr5 comment Interpretation of Riemann rearrangement theorem My gut feeling is that Nature does know how to add such things usually: E.g. in a lattice sum ordered by distance from the point of interest. At least this corresponds to the fact that in finite objects the infinite sum is only an approximation that ignores all far away points. And even in a truely infinite case, the finite age of the Universe does not allow any influence from too far away points ... Apr5 answered Are these subgroups of G only subgroups if G is abelian?