Van den Bergh's NCCR existence conjecture for affine Gorenstein toric varieties

Let Xσ=SpecRσX_\sigma=\operatorname{Spec} R_\sigma be an affine Gorenstein toric variety, where Rσ=k[σM]R_\sigma=k[\sigma^\vee\cap M] is the toric algebra associated to a full-dimensional cone σNR\sigma\subset N_\mathbb{R}, and suppose that there is an element mMm\in M satisfying m,uρi=1\langle m,u_{\rho_i}\rangle=1 for every primitive generator uρiu_{\rho_i} of a ray of σ\sigma. An NCCR is a non-commutative crepant resolution, namely an algebra of the form Λ=EndRσ(M)\Lambda=\operatorname{End}_{R_\sigma}(M') for a finitely generated reflexive RσR_\sigma-module MM' such that Λ\Lambda has finite global dimension and is maximal Cohen–Macaulay as an RσR_\sigma-module.

Van den Bergh's NCCR existence conjecture. Every affine Gorenstein toric variety has an NCCR.

The conjecture concerns the existence of non-commutative counterparts to crepant resolutions. The source states that it remains open, although NCCRs are known in a number of cases.

Sources & referencesView supporting material

Primary source

Aimeric Malter, “Conic modules, secondary fans and non-commutative resolutions”, arXiv:2603.23945 (2026).

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