Log del Pezzo surfaces with torus action - a searchable database

The ldp-database stores complex log del Pezzo surfaces admitting a non-trivial action by an algebraic torus. So the entries are either toric surfaces or non-toric with a non-trivial \( \mathbb{C}^* \)-action. The ldp-database is searchable through various invariants and properties such as Picard number, Gorenstein index, log canonicity, anticanonical self intersection and more.

The ldp-database contains complete classifications of log del Pezzo surfaces admitting a torus action with the following properties:

In total, the ldp-database contains 692.125 families of surfaces. The ldp-database is redundancy free, that means that different entries are non-isomorphic.

Contributions by: Daniel Hättig, Jürgen Hausen, Katharina Király, Justus Springer and Hendrik Süß.

References

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Basic properties:

The characteristic space of the surface is smooth, i.e. its singularities are at most toric.
The Cox Ring of the surface is defined by a single quadratic relation.
Constellation of source and sink of a non-toric \( \mathbb{C}^* \)-surface. "e" = elliptic fixed point, "p" = parabolic fixed point curve.
The dimension of the family of \( \mathbb{C}^* \)-surfaces.
e.g. 0, 3, ...
The rank of the Picard group (= rank of the class group).
e.g. 2, 7, ...
Self intersection number of an anticanonical divisor.
e.g. 9, 12/17, ...

Singularities:

The index of the Picard group inside the class group.
e.g. 31, 4040, ...
The smallest positive integer \( \iota \) such that \( \iota \) times an anticanonical divisor is Cartier.
e.g. 5, 124, ...
The maximum of all \( 0 < \varepsilon \leq 1 \) such that the surface is \( \varepsilon \)-log canonical.
e.g. 1/3, 3/5, ...
The number of singular points.
e.g. 0, 5, ...
The type of singularity of the elliptic fixed point in the source, if it exists. "A", "D" and "E" describe the shape of the resolution graph, while the following number counts the exceptional prime divisors in the minimal resolution of singularities.
e.g. 7, 12, ...
The type of singularity of the elliptic fixed point in the sink, if it exists. "A", "D" and "E" describe the shape of the resolution graph, while the following number counts the exceptional prime divisors in the minimal resolution of singularities.
e.g. 7, 12, ...

Kähler-Einstein metrics, Kähler-Ricci solitons and Sasaki-Einstein metrics:

See [5].
See [5].
See [5].

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