Reputation
5,101
Next privilege 10,000 Rep.
Access moderator tools
Badges
1 10 39
Newest
 Nice Answer
Impact
~57k people reached

Mar
12
awarded  Revival
Mar
12
revised $\mathbb{G}_a$ or $\mathbb{G}_m$ as subgroups of Affine Algebraic Groups
added 8 characters in body
Mar
12
answered $\mathbb{G}_a$ or $\mathbb{G}_m$ as subgroups of Affine Algebraic Groups
Mar
12
answered Prove that for each $p \in Y$ the quotient field of $O_p$ is isomorphic to the field $K(Y)$.
Mar
11
comment Resolution of singularities of the determinant hypersurface
This is indeed a very nice resolution. I would have preferred an embedded one, but this is quite a nice start, so +1 and accept. Thanks!
Mar
11
accepted Resolution of singularities of the determinant hypersurface
Mar
11
comment Can a birational morphism surject from an affine to a projective variety?
+1 and accept, also thank you, this is a nice proof.
Mar
11
accepted Can a birational morphism surject from an affine to a projective variety?
Mar
10
answered The 2 Charts of “Blowing up the Origin in $\mathbb{C}^2$ ”
Mar
7
answered why are projective spaces and varieties prefferable?
Mar
7
comment True or False: $f$ is injective if and only if $f^*$ is surjective where $f^*$ is corresponding to the pullback to $f$.
Of course, you can easily turn this into a direct proof, which is then more elegant. But it is late, and I will leave you with this.
Mar
7
answered True or False: $f$ is injective if and only if $f^*$ is surjective where $f^*$ is corresponding to the pullback to $f$.
Mar
6
comment Can a birational morphism surject from an affine to a projective variety?
@AlexYoucis: What is the argument for the fact that it has an inverse on some $U\subseteq Y$ whose complement is codim. 2? The approach sounds interesting!
Mar
4
comment Can a birational morphism surject from an affine to a projective variety?
@karl_christ: No, I mean surjective. Every fiber is nonempty.
Mar
4
comment Can a birational morphism surject from an affine to a projective variety?
@karl_christ: Such a map would only give me an isomorphism of a dense open subset $U\subseteq X$ with another dense open subset $V\subseteq Y$ of $Y$. This proves nothing.
Mar
4
comment Can a birational morphism surject from an affine to a projective variety?
@KReiser: Yea, I edited my question, this only makes sense for irreducible varieties.
Mar
4
revised Can a birational morphism surject from an affine to a projective variety?
added 41 characters in body
Mar
4
awarded  Electorate
Mar
4
answered Isomorphism between End$(V)\otimes A$ and End$_A(V\otimes A)$.
Mar
3
comment Can a birational morphism surject from an affine to a projective variety?
@Ben: I am not so much interested in pathologic cases, you may safely assume that all the objects are actually interesting.