geometry-topology / Birational geometry, Kodaira dimension and variation

Viehweg's conjecture C(n,m)+ and Popa's logarithmic Iitaka-Viehweg inequality

Theorem 1.1: for a projective surjective morphism f:U→Vf:U\to V with connected fibres between smooth connected complex quasi-projective varieties with κˉ(V)≥0\bar\kappa(V)\ge0 and geometric generic fibre FF, κˉ(U)≥κ(F)+max⁡{κˉ(V),Var(f)}\bar\kappa(U)\ge\kappa(F)+\max\{\bar\kappa(V),\mathrm{Var}(f)\}, with no good-minimal-model or abundance hypothesis on FF. Corollary 1.2 gives Viehweg's ordinary Cn,m+C^+_{n,m} for projective complex fibre spaces with κ(Y)≥0\kappa(Y)\ge0. Not covered: bases with κˉ(V)=−∞\bar\kappa(V)=-\infty, positive characteristic, and the additivity equalities for smooth families (a separate entry).

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geometry-topologySep 26, 2026Significance 45/100Registry: unreviewed

Viehweg's conjecture C(n,m)+ and Popa's logarithmic Iitaka-Viehweg inequality

Prior state unknown→proved

Theorem 1.1: for a projective surjective morphism f:U→Vf:U\to V with connected fibres between smooth connected complex quasi-projective varieties with κˉ(V)≥0\bar\kappa(V)\ge0 and geometric generic fibre FF, κˉ(U)≥κ(F)+max⁡{κˉ(V),Var(f)}\bar\kappa(U)\ge\kappa(F)+\max\{\bar\kappa(V),\mathrm{Var}(f)\}, with no good-minimal-model or abundance hypothesis on FF. Corollary 1.2 gives Viehweg's ordinary Cn,m+C^+_{n,m} for projective complex fibre spaces with…

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Theorem 1.1: for a projective surjective morphism f:U→Vf:U\to V with connected fibres between smooth connected complex quasi-projective varieties with κˉ(V)≥0\bar\kappa(V)\ge0 and geometric generic fibre FF, κˉ(U)≥κ(F)+max⁡{κˉ(V),Var(f)}\bar\kappa(U)\ge\kappa(F)+\max\{\bar\kappa(V),\mathrm{Var}(f)\}, with no good-minimal-model or abundance hypothesis on FF. Corollary 1.2 gives Viehweg's ordinary Cn,m+C^+_{n,m} for projective complex fibre spaces with κ(Y)≥0\kappa(Y)\ge0. Not covered: bases with κˉ(V)=−∞\bar\kappa(V)=-\infty, positive characteristic, and the additivity equalities for smooth families (a separate entry).

Theorem 1.1: for a projective surjective morphism f:U→Vf:U\to V with connected fibres between smooth connected complex quasi-projective varieties with κˉ(V)≥0\bar\kappa(V)\ge0 and geometric generic fibre FF, κˉ(U)≥κ(F)+max⁡{κˉ(V),Var(f)}\bar\kappa(U)\ge\kappa(F)+\max\{\bar\kappa(V),\mathrm{Var}(f)\}, with no good-minimal-model or abundance hypothesis on FF. Corollary 1.2 gives Viehweg's ordinary Cn,m+C^+_{n,m} for projective complex fibre spaces with κ(Y)≥0\kappa(Y)\ge0. Not covered: bases with κˉ(V)=−∞\bar\kappa(V)=-\infty, positive characteristic, and the additivity equalities for smooth families (a separate entry).

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