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The ordinary-double-point gap conjecture for normalized volumes of klt singularities

Theorem 1.1: for n≥2n\ge2 and a singular closed point of a normal complex algebraic nn-fold with KXK_X Q\mathbb Q-Cartier, klt with zero boundary, vol^(x,X)≤2(n−1)n\widehat{\mathrm{vol}}(x,X)\le2(n-1)^n, with equality iff the germ is analytically an ordinary double point; the point need not be isolated. The companion proves dimension four (bound 162), the base case. Corollary 1.2 gives a strict anticanonical volume bound below 2nn2n^n for singular K-semistable Q\mathbb Q-Fano nn-folds, so (−KV)n=2nn(-K_V)^n=2n^n off projective space only for the smooth quadric or P1×Pn−1\mathbb P^1\times\mathbb P^{n-1}. Not shown: nonzero boundary, the next gaps, or sharpness of the singular global bound.

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Prior state unknown→proved

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Occurred: Sep 24, 2026

Delta type: SOURCE CLAIM

Assumptions: VibeMathed verification: unreviewed. Publication: announcement. AI contribution: ai-discovered. VibeMathed editorial classifications, scores, notes, relations, and dataset structure are CC BY 4.0. Source statements and linked content retain their own rights.

Canonical aliases: The ordinary-double-point gap conjecture for normalized volumes of klt singularities · ODP normalized-volume gap

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Theorem 1.1: for n≥2n\ge2 and a singular closed point of a normal complex algebraic nn-fold with KXK_X Q\mathbb Q-Cartier, klt with zero boundary, vol^(x,X)≤2(n−1)n\widehat{\mathrm{vol}}(x,X)\le2(n-1)^n, with equality iff the germ is analytically an ordinary double point; the point need not be isolated. The companion proves dimension four (bound 162), the base case. Corollary 1.2 gives a strict anticanonical volume bound below 2nn2n^n for singular K-semistable Q\mathbb Q-Fano nn-folds, so (−KV)n=2nn(-K_V)^n=2n^n off projective space only for the smooth quadric or P1×Pn−1\mathbb P^1\times\mathbb P^{n-1}. Not shown: nonzero boundary, the next gaps, or sharpness of the singular global bound. parent of this event

The ordinary-double-point gap conjecture for normalized volumes of klt singularities parent of this event

VibeMathed record: The ordinary-double-point gap conjecture for normalized volumes of klt singularities evidence for this event

Companion: The normalized-volume gap in dimension four evidence for this event

Spotti-Sun, Explicit Gromov-Hausdorff compactifications (arXiv) evidence for this event

The ordinary-double-point gap conjecture for normalized volumes of klt singularities evidence for this event

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