Indecomposability conjecture for varieties with nef effective canonical bundle

Let XX be a smooth projective variety. A canonical bundle is nef and effective when KXK_X is nef and has a nonzero global section. A semiorthogonal decomposition of D ⁣cohb(X)D^b_{\!\operatorname{coh}}(X) is non-trivial when it has more than one nonzero component.

Indecomposability conjecture. If the canonical bundle KXK_X is nef and effective, then XX admits no non-trivial semiorthogonal decompositions.

This conjecture predicts indecomposability of derived categories for varieties whose canonical bundle has both numerical positivity and a section. The paper proves the claim under the stronger assumption that the base locus of KX|K_X| has dimension at most one, while the general case remains open.

Sources & referencesView supporting material

Primary source

Dmitrii Pirozhkov, “Admissible subcategories supported on curves”, arXiv:2506.16567 (2025).

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