Skip to main content
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
Results tagged with
Search options not deleted user 31356

Complex geometry is the study of complex manifolds, complex algebraic varieties, complex analytic spaces, and, by extension, of almost complex structures. It is a part of differential geometry, algebraic geometry and analytic geometry.

10 votes
1 answer
411 views

Kelly's theorem about a resolution of the Sylvester–Gallai problem

Kelly's theorem states: Every finite point set of complex space such that the line joining any two points from this set contains at least one more point from this set (every Sylvester-Gallai configara …
Alexey Milovanov's user avatar
3 votes
1 answer
240 views

Linear homogenous polynomials that generates several quadratic polynomials

This is a generalization of this question. Let $P_1, \ldots, P_m$, $Q_1, \ldots, Q_k \in \mathbb{C}[x_0,\ldots,x_n]$ be linear homogenous polynomials. Let $f_1, \ldots, f_s$ be a homogenous quadrati …
Alexey Milovanov's user avatar
2 votes
0 answers
205 views

Sylvester-Gallai-type theorem for quadratic polynomials

Let $F_1, F_2$ and $F_3$ be finites sets of irreducible polynomials in $\mathbb{C}[x_0, \ldots, x_n]$ of degree at most $2$ such that $F_1 \cap F_2 \cap F_3 = \varnothing$ and for every $Q_1, Q_2$ fr …
Alexey Milovanov's user avatar
2 votes
3 answers
331 views

Linear homogenous polynomials that generates one quadratic polynomial

Let $P_1, \ldots, P_m$, $Q_1, \ldots, Q_k \in \mathbb{C}[x_0,\ldots,x_n]$ be linear homogenous polynomials. Let $f$ be a homogenous quadratic polynomial of degree $2$. Assume that for every $i$ and f …
Alexey Milovanov's user avatar
2 votes
Accepted

Kelly's theorem about a resolution of the Sylvester–Gallai problem

I have found: https://arxiv.org/abs/1211.0330 Also https://arxiv.org/pdf/math/0403023.pdf (thank to Mike Miller).
Alexey Milovanov's user avatar
0 votes
0 answers
105 views

Kelly's theorem for quadratic polynomials

Let $f_1, \ldots, f_m$ be homogeneous irreducible quadratic polynomials in $\mathbb{C}[x_1, \ldots, x_n]$. Assume that these polynomials are pairwise coprime. Denote $P:= f_1 \cdot f_2 \ldots \cdo …
Alexey Milovanov's user avatar
0 votes
0 answers
288 views

Union of varieties

Let $Q_1, \ldots, Q_k$ and $P_1,\ldots, P_m$ be irredicable homogenous polynomials in $\mathbb{C}[x_0,\ldots, x_n]$ such that $V(Q_1, \ldots, Q_k) \subseteq \cup_i V(P_i)$. Here $V$ is projective vari …
Alexey Milovanov's user avatar
0 votes
Accepted

Linear homogenous polynomials that generates one quadratic polynomial

We will assume that $f$ is irreducible (if $f$ is not irreducible then in fact the argument of Zach Teitler's answer works). Consider $M:= f \cap P_1$ (I mean the intersection of the zeros $f$ and $P …
Alexey Milovanov's user avatar
0 votes
Accepted

Linear homogenous polynomials that generates several quadratic polynomials

Yes. 1) A quadratic homogenous polynomial $f$ (over $\mathbb{C}$) is irreducible iff $\text{rk}(f) \ge 3$. Here $\text{rk}(f)$ is the rank of $f$ as a quadratic form. Indeed, if $\text{rk}(f) < 3$ …
Alexey Milovanov's user avatar