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Cannon's conjecture
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Cannon's conjecture. Every word-hyperbolic group with boundary homeomorphic to S2 admits a proper cocompact isometric action on hyperbolic three-space with finite kernel, proving Cannon's conjecture. Every torsion-free such group is therefore the fundamental group of a closed hyperbolic three-manifold.

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released 2026-09-23  |  2 theorems · 22 lemmas · 30 proofs · 13,533 words  |  PLAY LEVEL 1 »  (pdf)
We prove that every hyperbolic group whose boundary is homeomorphic to the two-sphere admits a proper cocompact isometric action on hyperbolic three-space with finite kernel. This resolves Cannon's conjecture positively.

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