Ronald Bernard's user avatar
Ronald Bernard's user avatar
Ronald Bernard's user avatar
Ronald Bernard
  • Member for 11 years, 2 months
  • Last seen more than 8 years ago
26 votes
1 answer
4k views

Geometric meaning of completion and localization

12 votes
1 answer
2k views

Why is a variety etale locally like affine space?

9 votes
1 answer
2k views

Comparison between etale and singular cohomology for a singular variety

9 votes
2 answers
1k views

What is the homotopy colimit of the Cech nerve as a bi-simplical set?

8 votes
1 answer
482 views

What is the inverse limit of $...\to\mathbb{Z}\to\mathbb{Z}\to\mathbb{Z}$ (multiplying by all positive integers)?

7 votes
1 answer
3k views

Why can't this number be written as a sum of three squares of rationals?

7 votes
1 answer
539 views

Algebraic description of a stalk in the fppf topology

6 votes
1 answer
401 views

A question on an answer on Math Overflow about Artin approximation

6 votes
1 answer
511 views

Is the composite of an uniformly continuous sequence of functions with a bounded continuous function again uniformly continuous?

6 votes
1 answer
584 views

Glueing sheaves on Grothendieck sites

6 votes
3 answers
820 views

Does the inclusion from affine schemes into schemes preserve pushouts?

6 votes
2 answers
425 views

Why are quadratic forms so special and why not investigate in higher forms?

6 votes
2 answers
401 views

Does the functor $S:\mathbf{Top}\to \mathbf{sSets}$ preserve (homotopy)colimits?

6 votes
1 answer
187 views

Is this theorem of Dold easy to prove with the modern language at hand?

5 votes
1 answer
490 views

Is a pushout of a closed immersion $f$ again a closed immersion?

5 votes
1 answer
480 views

Are the right derived functors of the inclusion sheaf cohomology?

5 votes
3 answers
605 views

Compactness of the complex points of a $\mathbb{C}$-variety

5 votes
1 answer
932 views

Does the splitting principle define chern classes for vector bundles if they are known for line bundles?

5 votes
1 answer
160 views

What points of affine space can be mapped to zero by an étale morphism?

5 votes
1 answer
417 views

Different possibilities defining $\eta^2$ in the ring of stable homotopy groups?

4 votes
1 answer
97 views

Isomorphism or non-isomorphism of two specific local rings

4 votes
2 answers
1k views

Example of a non-free module over some Laurent polynomial ring

4 votes
1 answer
376 views

A question on an answer on Math Overflow about the tangent bundle

4 votes
3 answers
554 views

What finite fields are quadratically closed?

4 votes
0 answers
149 views

Does an equivariant weak equivalence induce weak equivalences on all orbits?

3 votes
0 answers
93 views

Does the $\mathcal{E}G$-construction arise form a comonad?

3 votes
1 answer
366 views

Is a pushout $W$ of schemes along a closed subscheme also a pullback?

3 votes
1 answer
726 views

Does the nerve of a category preserve directed colimits?

3 votes
1 answer
279 views

Can one apply the classifying space functor $B$ more than once?

3 votes
1 answer
382 views

Question on the formal completion of a ring $R$ w.r.t. an ideal $J$