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Generalized Cartan-Hadamard Conjecture


The generalized Cartan-Hadamard conjecture compares isoperimetric profiles of complete simply connected Riemannian manifolds with an upper bound on sectional curvature. If Sec_M<=kappa<=0, the proposed inequality is

 I_M(v)>=I_(M_kappa^d)(v),

where I_M(v) is the infimum of perimeters of finite perimeter sets of volume v in the d-dimensional manifold M, and M_kappa^d is the complete simply connected model of constant curvature kappa. The case kappa=0 is the Cartan-Hadamard conjecture, which gives the Euclidean isoperimetric inequality (Ghomi and Spruck 2022).

Agnoletto et al. (2026) reported the inequality in all dimensions, without an additional global lower Ricci-curvature bound in the smooth theorem. They also report that equality for a positive-volume finite perimeter set forces it to agree, up to a set of volume zero, with a region isometric to a model geodesic ball. Their treatment adapts analytic techniques from an earlier OpenAI manuscript and requires independent assessment. Agnoletto et al. (2026) report mathematical assistance from Claude and ChatGPT.


See also

Isoperimetric Inequality, Riemannian Manifold

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References

Agnoletto, M.; da Silva, M. F.; Nardulli, S.; and Resende, R. "The Generalized Cartan-Hadamard Conjecture." 27 Oct 2026. https://arxiv.org/abs/2610.37817.Ghomi, M. and Spruck, J. "Total Curvature and the Isoperimetric Inequality in Cartan-Hadamard Manifolds." J. Geom. Anal. 32, 50, 2022. https://doi.org/10.1007/s12220-021-00801-2.

Cite this as:

Weisstein, Eric W. "Generalized Cartan-Hadamard Conjecture." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/GeneralizedCartan-HadamardConjecture.html

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