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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.

12 votes
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Is the cup product of holomorphic $n$-forms with a fixed class injective?

The answer to this question is negative in dimensions $\ge 3$. For example, take a quintic in $\mathbb CP^4$ and consider its blow up $X$ in $10^{100}$ points (just to be safe). Then the space $H^1(X …
Dmitri Panov's user avatar
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11 votes

What do intermediate Jacobians do?

Recently I learned from a talk of Nick Addington one beautiful classical example where intermediate Jacobians contain all information about the variety. Namely, if we consider an intersection of two …
Dmitri Panov's user avatar
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11 votes

Two definitions of Calabi-Yau manifolds

You can prove that the canonical bundle is torsion without using Yau's theorem. This is contained the following work of Bogomolov, Theorem 3' F. A. Bogomolov, “Kähler manifolds with trivial canonica …
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3 votes

Dolbeault cohomology of Hopf manifolds

Maybe the following article by Soenke Rollenske (and refferences their), could be usefull for you: Some very non-Kähler manifolds: the Frölicher spectral sequence can be arbitrarily non degenerate h …
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7 votes
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Is the complex moduli of Quintic Calabi-Yau toric?

The complex moduli space does not admit a toric strucutre, since the orbifold fundamental group of a toric orbifold must be abelian. Indeed, $\pi_1(\mathbb C^*)^n$ surjects on the orbifold fundamental …
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5 votes
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Smooth algebraic varieties with smooth Kahler quotients.

The following article http://arxiv.org/abs/1102.2762 of BENOÎT CLAUDON, ANDREAS HÖRING, AND JÁNOS KOLLÁR answers positively the question, provided $V/G$ is projective, $V$ is quasiprojective and $\pi_ …
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6 votes
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symplectic classes on rational surfaces.

This answer is rewritten and include more details First of all I highly recommend you the article of Paul Biran From Symplectic Packing to Algebraic Geometry and Back available on the page http://ww …
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3 votes

"monotone" versus "symplectic Fano"

Edited. For the definitions that you mention "Simplectic Fano" can be non-montone. For example, you can take a $4$-dimensional Kahler non-agebraic torus that does not have complex curves at all. Such …
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4 votes

Algebraic Geometry versus Complex Geometry

1) I don't know if this qualifies, but it seems to me that there is no non-analytic proof of the statement that a surface of general type with $c_1^2=3c_2$ is a quotient of a unit two-dimensional comp …
7 votes

Holomorphic map from a neighborhood in $\mathbb C$ to S^3

Yes, such a map exists, and any such map has to be a map to a point in $\mathbb S^3$, because has to sends any holomorphic curve in the neighbourhood of $\mathbb C$ to a holomorphic curve in $S^3$, bu …
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8 votes
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Biholomorphism between neighborhood of a complex submanifold and a neighborhood of zero sect...

The existence of such a biholomorphism is rather rare. For example, as a simple exercise you can check that already for a conic in $\mathbb CP^2$ such a biholomorphism does not exist. At the same time …
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5 votes
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non-trivial locus of a holomorphic vector bundle

If your manifold is complex projective, then the answer is yes. Otherwise it is no. You can take a $K3$ surface without complex curves and just consider its tangent bundle. Of curse it will stay holom …
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1 vote
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Submersion to $ T^{2}$

Note first that $\Lambda\subset \mathbb C$ is a subgroup generated by a finite collection of numbers (periods) of the type $\alpha+i\beta$, where $\alpha,\, \beta\in \mathbb Q$. Such a subgroup is cl …
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1 vote

Concise expression for a specific holomorphic map $f:D\times D\longrightarrow \mathbb{B}^{2}$

Unfortunately, it doesn't look like the condition $\det(df)\subset(z_1z_2=0)$ is strong enough. Consider, for example, the map $$f:(z_1,z_2)\to (z_1, z_2^3+z_1z_2).$$ Clearly, the differential of t …
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4 votes
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Non-constant holomorphic map onto a smooth curve

Let me show that such a map usually doesn't exist (even if we don't remove any additional curves). Consider the case when $\Gamma$ is a curve of degree $\ge 4$. Then one can slightly perturb $\Gamma$ …
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