Bounded cohomology is not a profinite invariant
Canadian mathematical bulletin, Tome 67 (2024) no. 2, pp. 379-390
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We construct pairs of residually finite groups with isomorphic profinite completions such that one has non-vanishing and the other has vanishing real second bounded cohomology. The examples are lattices in different higher-rank simple Lie groups. Using Galois cohomology, we actually show that $\operatorname {SO}^0(n,2)$ for $n \ge 6$ and the exceptional groups $E_{6(-14)}$ and $E_{7(-25)}$ constitute the complete list of higher-rank Lie groups admitting such examples.
Mots-clés :
Profinite invariance, bounded cohomology, lattices in Lie groups
Echtler, Daniel; Kammeyer, Holger. Bounded cohomology is not a profinite invariant. Canadian mathematical bulletin, Tome 67 (2024) no. 2, pp. 379-390. doi: 10.4153/S0008439523000826
@article{10_4153_S0008439523000826,
author = {Echtler, Daniel and Kammeyer, Holger},
title = {Bounded cohomology is not a profinite invariant},
journal = {Canadian mathematical bulletin},
pages = {379--390},
year = {2024},
volume = {67},
number = {2},
doi = {10.4153/S0008439523000826},
url = {http://geodesic.mathdoc.fr/articles/10.4153/S0008439523000826/}
}
TY - JOUR AU - Echtler, Daniel AU - Kammeyer, Holger TI - Bounded cohomology is not a profinite invariant JO - Canadian mathematical bulletin PY - 2024 SP - 379 EP - 390 VL - 67 IS - 2 UR - http://geodesic.mathdoc.fr/articles/10.4153/S0008439523000826/ DO - 10.4153/S0008439523000826 ID - 10_4153_S0008439523000826 ER -
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