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arXiv · 2508.18237

Explicit Effective Birationality for Singular Surfaces

Pinxian Bie
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Abstract

We give some explicit upper bounds on the effective birationality of the canonical or anti-canonical system for a singular surface. In particular, we show that for any surface $X$ with $ε$-lc singularity and the canonical divisor $K_X$ or the anti-canonical divisor $-K_X$ is big and nef, then there exists explicit natural numbers $m$ and $l$ depending only on $ε$ such that $|mK_X|$ or $|-lK_X|$ defines a birational map. Although these explicit values are expected to be far from optimal, they are the first explicit upper bounds of this type for surfaces.

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Pinxian Bie. 2025-08-25. Explicit Effective Birationality for Singular Surfaces. https://arxiv.org/abs/2508.18237

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