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1d
comment Is it possible to replace $\lim$ by $\sup$ here?
Conventions are useful. In this case the convention that $\sup a_n=\infty$ if $a_n$ is not bounded above is useful, since it extends your claim nicely.
2d
comment Intuitive explanation why if $P$ is a subspace of linear space $L$, then $L/P$ is not a subspace of $L$
It is always isomorphic to a subspace of $L$. It depends on your definition of subspace.
Apr
22
comment Is $e^{e^9}$ an integer?
Yes, you can. ${}$
Apr
20
revised Given a general solution $y_1,y_2$ of $y''+p(x)y' + q(x)y = 0$ take $y_2=v y_1$ and show $\frac{dw}{dx} + (2 \frac{y_1'}{y_1}+p)w=0$ for $v'=w$
edited title
Apr
20
comment Prove carefully that $g(f(x)) \rightarrow l$ as $x \rightarrow x_0$
I can prove it but I cannot promise I'll be careful.
Apr
18
comment Show $\sigma^{-1} (i j)\sigma = ((i)\sigma (j)\sigma)$
Perhaps you mean $(\sigma(i)\sigma(j))$, or someone convinced to use quite nonstandard notation.
Apr
18
revised What are the hypotheses in Levi's monotone convergence theorem?
edited title
Apr
18
comment Standard deviation and mean question
Make titles informative and avoid 'desperate' requests for help, please.
Apr
18
revised If the localizations of two submodules with respect to any prime ideal are equal then the submodules are equal
edited body
Apr
18
answered If the localizations of two submodules with respect to any prime ideal are equal then the submodules are equal
Apr
18
revised Is there a term for an “unbounded simplex”?
edited tags
Apr
16
revised How to figure out how many entries are in a relation
rolled back to a previous revision
Apr
15
revised Addition and subtraction error
added 2 characters in body
Apr
14
awarded  Nice Question
Apr
14
comment When is a group isomorphic to a proper subgroup of itself?
@Pacman In the infinite case, there's no guarantee. Take $\Bbb Z$ and the proper isomorphic subgroup $2\Bbb Z$.
Apr
14
comment When is a group isomorphic to a proper subgroup of itself?
No, there isn't.
Apr
13
revised Conjugacy classes of the group $G=\langle a,b\mid a^6=1,b^2=a^3,bab^{-1}=a^{-1} \rangle$
edited body
Apr
13
comment Conjugacy classes of the group $G=\langle a,b\mid a^6=1,b^2=a^3,bab^{-1}=a^{-1} \rangle$
@AndreasCaranti Yes, that's a typo. Thanks.
Apr
13
awarded  ring-theory
Apr
13
comment What does the term “undefined” actually mean?
Do not make edits unless absolutely necessary. In particular, changing "mathematics" to "maths" is not absolutely necessary!