Variations on Nagata's Conjecture

By C. Ciliberto, Brian Harbourne, R. Miranda, Joaquim Roé. 2012

64 citations recorded by the source corpus.

In this paper we discuss some variations of Nagata's conjecture on linear systems of plane curves. The most relevant concerns non-effectivity (hence nefness) of certain rays, which we call \emph{good rays}, in the Mori cone of the blow-up $X_n$ of the plane at $n\ge 10$ general points. Nagata's original result was the existence of a good ray for $X_n$ with $n\ge 16$ a square number. Using degenerations, we give examples of good rays for $X_n$ for all $n\ge 10$. As with Nagata's original result, this implies the existence of counterexamples to Hilbert's XIV problem. Finally we show that Nagata's conjecture for $n\le 89$ combined with a stronger conjecture for $n=10$ implies Nagata's conjecture for $n\ge 90$.

Subfields: Algebra and Number Theory, Discrete Mathematics and Combinatorics, Geometry and Topology

View Paper: https://www.semanticscholar.org/paper/39c5688db3fb52b85029b4636096e1f94652c7ce

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In Algebra and Number Theory

  1. M. Catalisano
  2. Alessandro Gimigliano
  3. Alessandra Bernardi
  4. Enrico Carlini

In Discrete Mathematics and Combinatorics

  1. Enrico Carlini

In Geometry and Topology

  1. A. Oneto
  2. M. Catalisano
  3. Alessandro Gimigliano
  4. Alessandra Bernardi
  5. Enrico Carlini

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