Roland's user avatar
Roland's user avatar
Roland's user avatar
Roland
  • Member for 10 years, 3 months
  • Last seen this week
38 votes
Accepted

Grothendieck's yoga of six operations - in relatively basic terms?

26 votes
Accepted

Distinguished triangle induced by short exact sequence

21 votes
Accepted

Induced short exact sequence on wedge product

13 votes
Accepted

Geometric interpretation of ramification of prime ideals.

12 votes
Accepted

Scheme theoretic definition of a vector bundle

12 votes
Accepted

The support of a sheaf is not necessarily closed

12 votes
Accepted

Are long exact sequences in homology a special case of spectral sequences?

12 votes
Accepted

Wang Sequence for the circle $S^1$

11 votes
Accepted

Pullback of Sheaf Cohomology

11 votes
Accepted

Products and Sums of Sheaves

10 votes
Accepted

Godement Resolution don't see $\mathcal{O}_X$-module structure

10 votes
Accepted

Homology of a graph.

10 votes
Accepted

If F/K is an algebraic field extension, is every endomorphism of F/K an automorphism?

10 votes
Accepted

cover which is not Galois cover

10 votes
Accepted

Exactness and obstruction in sheaf cohomology

9 votes
Accepted

Why was O. Gabber not an author of the 1983's Faisceaux Pervers?

9 votes
Accepted

Showing that sheafification induces an isomorphism on stalks (without using adjoints)

9 votes
Accepted

Weil divisors fail over singular varieties

9 votes
Accepted

tensor product of sheaves is not a sheaf

8 votes
Accepted

How does Galois group acts on etale cohomology?

8 votes
Accepted

Understanding the maps in the long exact sequence of $\operatorname{Ext}$

8 votes
Accepted

Baer Sum notation requires clearence.

8 votes
Accepted

Vector field on a smooth variety

8 votes
Accepted

Invariant cycle theorem

8 votes
Accepted

Relative vs. local sheaf cohomology?

8 votes

Example of a local system

8 votes
Accepted

Does sheafification preserve flasqueness?

7 votes
Accepted

Definition of scheme defined over a ring A

7 votes

Example for an ideal which is not flat (and explicit witness for this fact)

7 votes
Accepted

Clifford Theorem as an easy corollary of Riemann-Roch Theorem

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