geometry-topology / Metric measure spaces; synthetic lower Ricci bounds; RCD spaces

Bi-Lipschitz charts at every regular point of a noncollapsed RCD(K,n) space

Claims that for every integer n≥2n\ge2 there is Ln≥1L_n\ge1 such that every regular point of every noncollapsed RCD(K,n)\mathrm{RCD}(K,n) space, K∈RK\in\mathbb R, has an open neighborhood LnL_n-bi-Lipschitz homeomorphic, with the ambient distance, to an open subset of Rn\mathbb R^n; the neighborhood depends on the space and the point. Corollary: an open set of full Hn\mathcal H^n measure containing all regular points carries a countable bi-Lipschitz atlas with Ln2L_n^2 transition maps. It does NOT claim that the regular set is open, any collapsed or non-RCD statement, or regularity of the metric tensor in the charts.

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geometry-topologySep 25, 2026Significance 24/100Registry: unreviewed

Bi-Lipschitz charts at every regular point of a noncollapsed RCD(K,n) space

Prior state unknown→proved

Claims that for every integer n≥2n\ge2 there is Ln≥1L_n\ge1 such that every regular point of every noncollapsed RCD(K,n)\mathrm{RCD}(K,n) space, K∈RK\in\mathbb R, has an open neighborhood LnL_n-bi-Lipschitz homeomorphic, with the ambient distance, to an open subset of Rn\mathbb R^n; the neighborhood depends on the space and the point. Corollary: an open set of full Hn\mathcal H^n measure containing all regular points carries…

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Claims that for every integer n≥2n\ge2 there is Ln≥1L_n\ge1 such that every regular point of every noncollapsed RCD(K,n)\mathrm{RCD}(K,n) space, K∈RK\in\mathbb R, has an open neighborhood LnL_n-bi-Lipschitz homeomorphic, with the ambient distance, to an open subset of Rn\mathbb R^n; the neighborhood depends on the space and the point. Corollary: an open set of full Hn\mathcal H^n measure containing all regular points carries a countable bi-Lipschitz atlas with Ln2L_n^2 transition maps. It does NOT claim that the regular set is open, any collapsed or non-RCD statement, or regularity of the metric tensor in the charts.

Claims that for every integer n≥2n\ge2 there is Ln≥1L_n\ge1 such that every regular point of every noncollapsed RCD(K,n)\mathrm{RCD}(K,n) space, K∈RK\in\mathbb R, has an open neighborhood LnL_n-bi-Lipschitz homeomorphic, with the ambient distance, to an open subset of Rn\mathbb R^n; the neighborhood depends on the space and the point. Corollary: an open set of full Hn\mathcal H^n measure containing all regular points carries a countable bi-Lipschitz atlas with Ln2L_n^2 transition maps. It does NOT claim that the regular set is open, any collapsed or non-RCD statement, or regularity of the metric tensor in the charts.

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Bi-Lipschitz charts at every regular point of a noncollapsed RCD(K,n) space — Mathematical Frontier Network