The 1-1-curves conjecture for blowups of the projective plane

Let S=SnS=S_n be the blowup of the projective plane at nn very general points. Let NR1(S)N^1_{\mathbb R}(S) be the real Néron–Severi space, let NE(S)\overline{\operatorname{NE}}(S) be the Mori cone, and let L\mathscr L denote the light cone. A 1-1-curve is a curve cSc\subset S isomorphic to P1\mathbb P^1 with c2=1c^2=-1.

1-1-curves conjecture. The Mori cone of SS is generated by the light cone and the 1-1-curves. Dually,

Nef(S)={vLvc0 for every 1-curve cS}.\operatorname{Nef}(S)=\{v\in\mathscr L\mid v\cdot c\ge 0\text{ for every }-1\text{-curve }c\subset S\}.

This conjecture concerns the geometry of the Mori and nef cones for blowups at very general points, particularly when n>9n>9, where these cones are not completely understood. The source attributes it to Tommaso de Fernex and cites an erratum, but gives no resolution status.

Sources & referencesView supporting material

Primary source

Luíze D'Urso, “On the Nef cones of blowups of the projective plane”, arXiv:2412.15460 (2025).

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