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1h
comment Does the five lemma hold true for Lie algebras?
If you replace "epimorphism" by "surjective map" then you can use the $5$ lemma from the category of vector spaces. But in general I'm not sure if Lie algebra epi's are necessarily surjective. I would guess not and I would guess that this breaks the $5$ lemma.
23h
awarded  Nice Answer
1d
answered Can an empty set be both torsion and torsion free group?
1d
comment Showing that the image of a morphism is algebraic curve
Also x^3 - z^2 = xz^4 - w^4 = 0$. But now there's more than three...
1d
comment Showing that the image of a morphism is algebraic curve
Off the top of my head I also see $xz - y^2 = 0$.
1d
comment Correspondence between ideals of $R$ and $D^{-1}R$
Yep, posted as an answer.
1d
answered Correspondence between ideals of $R$ and $D^{-1}R$
1d
comment Correspondence between ideals of $R$ and $D^{-1}R$
But $R$ intersects $D$, it's not part of the correspondence.
1d
comment Correspondence between ideals of $R$ and $D^{-1}R$
Ok, take $D = \{1\}$, which ideal extends to the ideal $D^{-1}R$?
1d
comment Correspondence between ideals of $R$ and $D^{-1}R$
What happens if $0 \in D$?
1d
answered A subgroup of $\mathbb{Z}$
2d
comment Which of the following are true?
Please don't make the title all math, it prevents people from right clicking to open in a new tab which is how many of us browse this site.
2d
revised Which of the following are true?
edited title
Nov
24
comment Algebra ring theory
Can you define $2\mathbb R$ for us? Because I would normally define $2\mathbb R = \{2x \ | \ x \in \mathbb R\}$ and if that's what you mean then $2\mathbb R = \mathbb R$.
Nov
24
answered Linear maps, inverses and associated matrices?
Nov
24
comment Algebra: Help with these expressions about inverse matrix
I don't know where you got that expression, nor do I know if it has a name.
Nov
23
revised Algebra: Help with these expressions about inverse matrix
added 82 characters in body
Nov
23
answered Algebra: Help with these expressions about inverse matrix
Nov
23
answered closed and open subscheme of affine scheme
Nov
23
comment Finding the Jordan basis of a linear map
If $A^3 = 0$ then all eigenvalues are zero. Of course I haven't checked that $A^3 = 0$, I'm just taking the OP's word on that.