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Nov
19 |
revised |
When is a submanifold of $\mathbf R^n$ given by global equations?
edited tags |
Nov
18 |
revised |
Gysin exact sequence for a singular subvariety
added 7 characters in body |
Nov
18 |
revised |
Gysin exact sequence for a singular subvariety
added 40 characters in body |
Nov
18 |
revised |
Gysin exact sequence for a singular subvariety
edited tags |
Nov
17 |
awarded | Yearling |
Nov
17 |
asked | Gysin exact sequence for a singular subvariety |
Oct
9 |
awarded | Informed |
Oct
9 |
comment |
Algebraic proof without using comparison theorem for étale cohomology
This fix looks very nice. I accepted the previous answer because it appeared first. Thank you anyway! |
Oct
9 |
accepted | Algebraic proof without using comparison theorem for étale cohomology |
Oct
8 |
asked | Algebraic proof without using comparison theorem for étale cohomology |
Sep
30 |
reviewed | No Action Needed For which rings R is SL_n(R) generated by transvections? |
Sep
30 |
reviewed | No Action Needed character degree and solvability |
Sep
30 |
awarded | Custodian |
Sep
30 |
reviewed | No Action Needed Occurrences of (co)homology in other disciplines and/or nature |
Sep
25 |
comment |
Is SL(n,Z[x]) generated by transvections?
Just to clarify: the conclusion of the discussion you mention about the stable range of $\mathbf Z [x]$ was that it is indeed of stable range $3$. It is proven in the paper by Grunewald, Mennicke, and Vaserstein mentionned by "few_reps" as indicated in the discussion. |
Sep
24 |
comment |
Is SL(n,Z[x]) generated by transvections?
Cohn was probably the first to prove that $\mathrm{SL}_2(\mathbf{Z}[T]) \neq \mathrm{E}_2(\mathbf{Z}[T])$. A concrete example of a matrix not in $\mathrm{E}_2$ is $\begin{bmatrix} 1+2T & 4 \cr -T^2 & 1-2T\end{bmatrix}$. I took this example from Lam's "Serre's problem on projective modules", rk 8.11. |
Sep
4 |
answered | Examples of naturally occurring Quadratic forms or quadrics. |
Apr
8 |
comment |
Reference Request: Grouplike Algebras over the little $n$-cubes operad are $n$-fold loop spaces
Adams, "Infinite loop spaces" seems to be the reference you are looking for. |
Dec
17 |
comment |
Given a positive-definite integral unimodular Gram matrix, how to find a basis of the associated lattice (over $\mathbf Q$)?
Ok, I know why it represents a square, but is there an algorithmic way to find such a vector? |
Dec
17 |
comment |
Given a positive-definite integral unimodular Gram matrix, how to find a basis of the associated lattice (over $\mathbf Q$)?
I am a bit confused by the first step. My (stupid) question is: why does a positive definite 4-dimensional integral quadratic form represent a square? |