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8 votes
2 answers
452 views

Necessary condition on Calabi-Yau manfiold to be a hypersurface in a Fano manifold

Let $X$ be a smooth projective Calabi-Yau threefold. Are there any known obstructions to it being a member of a base-point-free linear system in a nef-Fano fourfold? What, in anything, is known ...
Lev Borisov's user avatar
  • 5,156
7 votes
0 answers
204 views

Does there exists a compact Ricci-flat K3 surface whose metric tensor is expressed in explicit formula?

Yau's theorem showed the existence. But I had difficulty finding examples other than complex tori. Any information will be appreciated.
clvolkov's user avatar
  • 193
6 votes
0 answers
347 views

Quantifying the failure of geometric formality in K3 surfaces

It is known that K3 surfaces are never geometrically formal [1]. That is, the wedge product of two harmonic forms on an arbitrary K3 surface is in general not harmonic, or equivalently, the space $\...
Arpan Saha's user avatar
5 votes
2 answers
940 views

Are any two K3 surfaces over C diffeomorphic?

Let $S$ be a K3 surface over $\mathbb{C}$, that is, $S$ is a simply connected compact smooth complex surface whose canonical bundle is trivial. I recall reading somewhere that any two such surfaces ...
Daniel Loughran's user avatar
4 votes
2 answers
312 views

Algebraic cycles on a K3 surface after hyperKahler rotation.

I would like to find a gap in the following observation. I found a suspicious part but cannot prove it wrong. I would appreciate your assistance. Let $M$ be a lattice of signature $(1,t)$ and $S$ be ...
YJiang's user avatar
  • 41
2 votes
1 answer
168 views

Concrete descriptions of $S^1$-bundles over smooth manifold $Y$ underying a K3 surface

Let $Y$ be the smooth manifold underlying a K3 surface. As a manifold, $Y$ is diffeomorphic to $\{[x_0:x_1:x_2:x_3]\in\mathbb{C}P^3\colon X_0^4+x_1^4+X_2^4+X_3^4=1\}$. It is well known that $H^2(Y,\...
James's user avatar
  • 133
2 votes
1 answer
460 views

Isometry of K3 surface.

Let $S$ be a K3 surface and $\iota$ be anti-symplectic involution of $S$. Suppose that $g$ is a Kahler-Einstein metric on $S$. My question is; Why $\iota$ is an isometry of $S$ with respect to $g$?...
Zheng's user avatar
  • 21
2 votes
0 answers
83 views

Explicit Lagrangian fibrations of a K3 surface

I would like to look at the behaviour of the fibres of a Lagrangian fibration (such that at least some fibres are not special Lagrangian) $X\to\mathbb{CP}^1$ under the mean curvature flow (in relation ...
Quaere Verum's user avatar