Cannon's conjecture on hyperbolic groups with two-sphere boundary

Let GG be a Gromov hyperbolic group whose boundary at infinity is homeomorphic to the two-sphere S2\mathbb{S}^2. A group is virtually Kleinian if, up to a finite-index subgroup, it can be realized as a group of discrete, cocompact isometries of real hyperbolic three-space HR3H^3_{\mathbb{R}}. Cannon's conjecture. If G\partial_\infty G is homeomorphic to S2\mathbb{S}^2, then GG is virtually Kleinian. This is the two-dimensional boundary case of the relationship between the large-scale geometry of hyperbolic groups and geometric actions on real hyperbolic space; the conjecture remains open.

Sources & referencesView supporting material

Primary source

Guy C. David, Pekka Pankka and Jeremy T. Tyson, “The Heinonen-Semmes problems after thirty years”, arXiv:2510.19179 (2025).

Additional references

13 papers in this index state this conjecture (2002–2025). The statement above is taken from the most recent of them; the others are arXiv:2508.01075, arXiv:2507.11337, arXiv:2406.14667, arXiv:2405.20428, arXiv:2111.00342, arXiv:1805.12583, arXiv:1804.00738, arXiv:1603.01023, arXiv:1411.3562, arXiv:math/0701370, arXiv:math/0612605, arXiv:math/0208135.

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