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Feb
2
awarded  Nice Answer
Jan
28
comment Adjoint to $\mathsf{Proj}$? - A quest to understand categories of graded objects.
Proj is not a functor.
Jan
17
comment Question on syzygies
There is a systematic theory for doing these kind of computations and that is the theory of Gröbner bases. In general however, the algorithms are too complex to be done by hand. Computer algebra systems such as Macaulay2 do them for you.
Jan
16
answered Show a homomorphism of local rings of two varieties
Jan
12
comment If $\phi:A\to B$ is a ring homomorphism, why does there exist $\psi:\text{spec}(A)\to \text{spec}(B)$?
What ${\phi^{\ast}}^{-1}$ means is not the inverse (because that generally does not exist) but the inverse image, and that is what the book refers to.
Jan
3
answered Surjectivity of morphisms of smooth projective varieties
Jan
1
awarded  Enlightened
Jan
1
awarded  Nice Answer
Dec
23
comment Determining the structure of the quotient ring $\mathbb{Z}[x]/(x^2+3,p)$
@user1337 It is hard to understand precisely what is ment by "structure" here, so I'm not completely sure what is "right" answer to this exercise. To me it seems that you have ample understanding of quotient rings, though.
Dec
23
answered Determining the structure of the quotient ring $\mathbb{Z}[x]/(x^2+3,p)$
Dec
22
comment Geometric meaning of prime elements?
How much background do you have? Have you heard of schemes?
Dec
6
answered Normal bundle to complete intersection in $\mathbb{P}^n$
Dec
6
awarded  Nice Answer
Dec
1
awarded  Yearling
Nov
23
answered Do we have $End(V \otimes V) = End(V) \otimes End(V)$?
Nov
17
comment If a quotient group G/H is cyclic then is G also cyclic?
Take $G=\mathbb Z/2 \times \mathbb Z/4$ and $H = \mathbb Z /2 \times \{ 0 \}$.
Nov
15
answered calculating syzygies with Macaulay2
Nov
11
answered Restriction of a dominant map
Nov
4
answered Computing Extensions of an Ideal in Singular or Macaulay2
Nov
3
answered Inverse of invertible sheaf