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Residual Finiteness of Hyperbolic Groups

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· geometric group theory · ~1 min read · difficulty 4/5

geometric-group-theory

The problem

Question (Gromov): is every Gromov-hyperbolic group residually finite? That is, for every non-identity \(g\) does there exist a homomorphism to a finite group not killing \(g\)?

History & significance

Gromov's 1987 essay founding hyperbolic group theory asked which of their properties mirror 3-manifold groups — residual finiteness among the most basic. Agol–Wise virtual specialness (2012) settled virtual Haken-type questions for many hyperbolic groups without implying residual finiteness; non-residually-finite hyperbolic examples would have to be non-linear (all linear groups are residually finite by Malcev), and none are known. A counterexample would be as shocking as a proof.

Still open.

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