In this note, we show that if all Lyapunov exponents of a matrix cocycle vanish, then it can be perturbed to become cohomologous to a cocycle taking values in the orthogonal group. This extends a result of Avila, Bochi and Damanik to general base dynamics and arbitrary dimension. We actually prove a fibered version of this result, and apply it to study the existence of dominated splittings into conformal subbundles for general matrix cocycles.
@article{AIHPC_2014__31_6_1101_0, author = {Bochi, Jairo and Navas, Andr\'es}, title = {Almost reduction and perturbation of matrix cocycles}, journal = {Annales de l'I.H.P. Analyse non lin\'eaire}, volume = {31}, year = {2014}, pages = {1101-1107}, doi = {10.1016/j.anihpc.2013.08.004}, mrnumber = {3280061}, zbl = {1332.37026}, language = {en}, url = {http://dml.mathdoc.fr/item/AIHPC_2014__31_6_1101_0} }
Bochi, Jairo; Navas, Andrés. Almost reduction and perturbation of matrix cocycles. Annales de l'I.H.P. Analyse non linéaire, Tome 31 (2014) pp. 1101-1107. doi : 10.1016/j.anihpc.2013.08.004. http://gdmltest.u-ga.fr/item/AIHPC_2014__31_6_1101_0/
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