Kawamata–Morrison cone conjecture for K-trivial fiber spaces

Let f:XSf:X\to S be a KK-trivial fiber space, meaning a normal Q\mathbb Q-factorial klt pair (X,Δ)(X,\Delta) endowed with a proper surjective morphism with connected fibres such that KX+Δf0K_X+\Delta\equiv_f0. Write Move(X/S):=Mov(X/S)Eff(X/S)\overline{\operatorname{Mov}}^e(X/S):=\overline{\operatorname{Mov}}(X/S)\cap\operatorname{Eff}(X/S) and Nefe(X/S):=Nef(X/S)Eff(X/S)\operatorname{Nef}^e(X/S):=\operatorname{Nef}(X/S)\cap\operatorname{Eff}(X/S). Kawamata–Morrison cone conjecture. There exists a rational polyhedral cone Π\Pi such that

Move(X/S)=gPsAut(X/S)gΠ,\overline{\operatorname{Mov}}^e(X/S)=\bigcup_{g\in\operatorname{PsAut}(X/S)}g^*\Pi,

and

Π(gΠ)=\Pi^\circ\cap(g^*\Pi)^\circ=\emptyset

for every gPsAut(X/S)g\in\operatorname{PsAut}(X/S), except when g=1g^*=1 in GL(N1(X/S))\operatorname{GL}(N^1(X/S)). There also exists a rational polyhedral cone Π\Pi' satisfying the analogous fundamental-domain conditions for the action of Aut(X/S)\operatorname{Aut}(X/S) on Nefe(X/S)\operatorname{Nef}^e(X/S). The conjecture predicts rational polyhedral fundamental domains for the movable and nef cones; in the source paper, the stated version is proved under the hypotheses described in the abstract, while the supplied span itself gives no resolution status for the general formulation.

Sources & referencesView supporting material

Primary source

Aurélien Faucher, “The Cone Conjecture for Primitive Symplectic Varieties over a Field of Characteristic Zero and an Application”, arXiv:2512.19656 (2026).

Additional references

13 papers in this index state this conjecture (2012–2025). The statement above is taken from the most recent of them; the others are arXiv:2503.03949, arXiv:2412.15460, arXiv:2410.11987, arXiv:2406.07307, arXiv:2207.11150, arXiv:2112.01352, arXiv:2103.11638, arXiv:2005.04254, arXiv:1601.01273, arXiv:1311.6612, arXiv:1210.1903, arXiv:1206.1649.

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