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 Apr 22 answered Given a normed space $X$ and $A:X\to\mathbb R$, how can I compute the second Fréchet derivative of $f(t):=A(x_0+th)$ for some $x_0,h\in X$? Apr 1 revised Repeated Indefinite Integration of Gaussian Integral deleted 117 characters in body Apr 1 comment Why is $\text{Exterior}(A) = \text{int}(A^c) = \text{cl}(A)^c$? @MichaelBurr No problem. Apr 1 comment Why is $\text{Exterior}(A) = \text{int}(A^c) = \text{cl}(A)^c$? @MichaelBurr Sure. But there are different definitions of closure and interior out there, so I asked. Apr 1 comment Intersection of nested compact sets in a Hausdorff space Then $X = \bigcap_{i=1}^n U_i = U_n$ (the $U_n$ are increasing). But $U_n = X$ gives $X_n = \emptyset$, which is wrong. (If $x \in X$, then $f^{n-1}(x) \in X_n$. Apr 1 revised Intersection of nested compact sets in a Hausdorff space edited body Apr 1 comment Why is $\text{Exterior}(A) = \text{int}(A^c) = \text{cl}(A)^c$? How do you define $A^°$ and $\bar A$? Apr 1 answered Intersection of nested compact sets in a Hausdorff space Apr 1 answered How many numbers are possible from $a^x b^y c^z$? Apr 1 answered $x$ and $f(x)$ are linear dependent then $f(x) = kx$. Mar 30 answered Differentiating between standard and non-standard interpretations of 'less than' relation Mar 25 comment Is there a way to calculate absurdly high powers? You start from 1 ... usually Mar 25 awarded Good Answer Mar 25 awarded ring-theory Mar 24 answered Quotients of $L_1$ Mar 24 comment Can I found $U$, $W$, and $X$ subspace in $V$ which satisfies $(U\cap X)+(W \cap X)\subset(U+W)\cap X.$ What do you denoe by $\subset$? A proper subset, I suppose. Mar 24 revised Can I found $U$, $W$, and $X$ subspace in $V$ which satisfies $(U\cap X)+(W \cap X)\subset(U+W)\cap X.$ deleted 9 characters in body; edited title Mar 24 revised Is every ideal of $R$ a sum of a nilpotent ideal and an idempotent ideal? added 1 character in body Mar 24 answered Show $\sum_{k=1}^\infty \frac{k^2}{k!} = 2\mathrm{e}$ Mar 23 comment How To differentiate this integral @Vim edited.