The (weak) Kawamata–Morrison cone conjecture for K-trivial fibrations

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Let f:(X,Δ)→Sf:(X,\Delta)\to S be a klt KK-trivial fiber space. Define

Nef⁡+(X/S):=Conv⁡(Nef⁡(X/S)∩N1(X/S)Q)\operatorname{Nef}^+(X/S):=\operatorname{Conv}\left(\operatorname{Nef}(X/S)\cap N^1(X/S)_\mathbb Q\right)

and

Mov⁡+(X/S):=Conv⁡(Mov⁡‾(X/S)∩N1(X/S)Q).\operatorname{Mov}^+(X/S):=\operatorname{Conv}\left(\overline{\operatorname{Mov}}(X/S)\cap N^1(X/S)_\mathbb Q\right).

A subset is a weak fundamental domain for a group action if its translates cover the space and every translate either equals it or is disjoint from its interior. The (weak) Kawamata–Morrison cone conjecture. (1) There exists a rational polyhedral cone Π\Pi which is a weak fundamental domain for the action of the group of relative automorphisms Aut⁡(X/S,Δ)\operatorname{Aut}(X/S,\Delta) preserving the boundary on Nef⁡+(X/S)\operatorname{Nef}^+(X/S). (2) There exists a rational polyhedral cone Π′\Pi' which is a weak fundamental domain for the action of the group of relative pseudoautomorphisms PsAut⁡(X/S,Δ)\operatorname{PsAut}(X/S,\Delta) preserving the boundary on Mov⁡+(X/S)\operatorname{Mov}^+(X/S). These assertions give rational polyhedral fundamental-domain descriptions of the relative nef and movable cones, extending the Kawamata–Morrison cone conjecture to klt KK-trivial fibrations; their resolution status is not specified in the supplied text.

References

Primary source

Aurélien Faucher, “The relative movable cone conjecture for K-trivial fibrations in varieties with well-clipped movable cones”, arXiv:2603.22457 (2026).

Additional references

2 papers in this index state this conjecture (2025–2026). The statement above is taken from the most recent of them; the others are arXiv:2512.19656.

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