Bounded cohomology and isometry groups of hyperbolic spaces
Journal of the European Mathematical Society, Tome 10 (2008) no. 2, pp. 315-349
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Let X be an arbitrary hyperbolic geodesic metric space and let Γ be a countable subgroup of the isometry group Iso(X) of X. We show that if Γ is non-elementary and weakly acylindrical (this is a weak properness condition) then the second bounded cohomology groups Hb2(Γ,R), Hb2(Γ,lp(Γ)) (1∞) are infinite dimensional. Our result holds for example for any subgroup of the mapping class group of a non-exceptional surface of finite type not containing a normal subgroup which virtually splits as a direct product.
@article{JEMS_2008_10_2_a1,
author = {Ursula Hamenst\"adt},
title = {Bounded cohomology and isometry groups of hyperbolic spaces},
journal = {Journal of the European Mathematical Society},
pages = {315--349},
publisher = {mathdoc},
volume = {10},
number = {2},
year = {2008},
doi = {10.4171/jems/112},
url = {http://geodesic.mathdoc.fr/articles/10.4171/jems/112/}
}
TY - JOUR AU - Ursula Hamenstädt TI - Bounded cohomology and isometry groups of hyperbolic spaces JO - Journal of the European Mathematical Society PY - 2008 SP - 315 EP - 349 VL - 10 IS - 2 PB - mathdoc UR - http://geodesic.mathdoc.fr/articles/10.4171/jems/112/ DO - 10.4171/jems/112 ID - JEMS_2008_10_2_a1 ER -
Ursula Hamenstädt. Bounded cohomology and isometry groups of hyperbolic spaces. Journal of the European Mathematical Society, Tome 10 (2008) no. 2, pp. 315-349. doi: 10.4171/jems/112
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