Search Results
Search type | Search syntax |
---|---|
Tags | [tag] |
Exact | "words here" |
Author |
user:1234 user:me (yours) |
Score |
score:3 (3+) score:0 (none) |
Answers |
answers:3 (3+) answers:0 (none) isaccepted:yes hasaccepted:no inquestion:1234 |
Views | views:250 |
Code | code:"if (foo != bar)" |
Sections |
title:apples body:"apples oranges" |
URL | url:"*.example.com" |
Saves | in:saves |
Status |
closed:yes duplicate:no migrated:no wiki:no |
Types |
is:question is:answer |
Exclude |
-[tag] -apples |
For more details on advanced search visit our help page |
Algebraic varieties, stacks, sheaves, schemes, moduli spaces, complex geometry, quantum cohomology.
15
votes
Accepted
Is there a "weak" fundamental theorem of algebra for matrices?
No, for rather trivial reasons. Consider the polynomial $f(X) = \varepsilon X - 1$ with $\varepsilon^2 = 0$, $\varepsilon \neq 0$, in $R = M_2(\mathbb{C})$. Then a root of $f(X)$ would mean that $\var …
10
votes
1
answer
693
views
Has the geometry of the variety of nilpotent matrices over $\mathbb{C}$ been studied?
Consider the complex projective variety given by $X^n = 0$, where $X\in \mathrm{M}_n(\mathbb{C})$ and, say, $n\geq 3$. Some basic properties of it are already mentioned in this question:
https://mat …
7
votes
Accepted
Does T-T Moh's paper really contain a gap?
Yes, there appears to be a follow-up work by Yansong Xu on the (99,66)-case: Intersection Numbers and the Jacobian Conjecture, in turn followed by The Jacobian Conjecture: Approximate roots and inters …
6
votes
Accepted
Question about Jacobian conjecture on the reals
To (Q1): Yes, $F$ being invertible means in this context exactly that $F$ admits a polynomial compositional inverse. If you are working over a general commutative ring $k$, then invertibility of $J_F$ …
5
votes
0
answers
276
views
Have complex manifolds with dual number structure on the holomorphic tangent bundle been stu...
If $M$ denotes a $2n$-dimensional real smooth manifold, then $M$ together with
$J\in\operatorname{End}(TM)$ with $J^2 =\mathrm{id}$ (also called almost product structure on $M$) have been surveyed i …
5
votes
0
answers
472
views
Formal multidimensional Taylor series expansion over commutative rings
If $F:V\to W$ is a smooth at $a\in V$ function between finite-dimensional vector spaces over $\mathbb{R}$, then we have
$$
F(x) = \sum_{k=0}^N\frac{1}{k!}(D^kF)(a)[(x-a)^{\otimes k}]+\text{remainder}, …
5
votes
0
answers
180
views
The precise relationship between (moduli space of) finite-dimensional commutative local $\ka...
In [BP08] Poonen constructs and studies $\mathfrak{B}_n$, the moduli space of all based $n$-dimensional commutative associative unital $\kappa$-algebras, where $\kappa$ is an algebraically closed fiel …
5
votes
Questions about some parallel between polynomial and differential equation
To (Q1): Yes, see Differential Galois Theory. For example, the Galois group of the Airy equation over $\mathbb{C}$ is given by the Lie group $\operatorname{SL}_2(\mathbb{C})$.
To (Q2): Yes, see (Q4).
…
4
votes
1
answer
282
views
The $1$-dimensional Jacobian Conjecture over $\mathbb{Z}$-torsion free rings
I am looking for further proofs, preferably in the literature, of the following result:
Proposition: Let $R$ be a unital commutative $\mathbb{Z}$-torsion free ring. If $f(x) \in R[x]$ with $f'(x) \in …
4
votes
Books one can read for 2nd course in Commutative Algebra ( Self Study)
I would suggest Altman and Kleiman's "A Term of Commutative Algebra". As far as I know, the most recent version can be found at https://dspace.mit.edu/handle/1721.1/116075.2.
Quoting from the preface: …
3
votes
Which commutative rings have irreducible (maximal) spectra?
Let $A$ be a commutative ring with unity. Denote $X:=Spec(A)$.
$X$ is connected if and only if $A$ cannot be written as a Cartesian product $A_1\times A_2$ for nontrivial $A_1$ and $A_2$. So, that g …
3
votes
Accepted
Regular local artinian k-algebra with residue field k is k
A local ring $(A,\mathfrak{m})$ is regular iff the minimal number of generators of $\mathfrak{m}$ equals the Krull dimension of $A$. But Artinian rings have Krull dimension $0$, i.e. $\mathfrak{m}=0$, …
2
votes
2
answers
365
views
Can a non-zero non-prime ideal become prime in a smaller ring?
All rings are assumed commutative and unital.
Some context (feel free to skip right to the questions below). I am trying to understand to what extent the property "being prime" for an ideal $I$ is int …
1
vote
0
answers
126
views
A Weierstrass product theorem for invertible formal Laurent series over local Artinian rings?
Let $(A,\mathfrak{m},\kappa)$ denote a commutative local Artinian ring. Somewhat by accident, I've stumbled across the following interesting decomposition:
$$
A(\!(t)\!)^\times = t^\mathbb{Z} \cdot (1 …
1
vote
General algebraic definition of mirror symmetry
I don't know if there is a more up-to-date precise statement for $\mathbb{F}_n$ uniformly for all $n \in \mathbb{N}$, my knowledge is definitely not recent, but here is what I know.
Denote your LG-mod …