Preprint A34/2001
A formula with some aplications to the theory of Lyapunov exponents

Jairo Bochi | Avila, Artur

**Keywords: **
Lyapunov Exponents

We prove an elementary formula about the average expansion of certain
products of matrices. This permits us to quickly reobtain
an inequality by M. Herman and a theorem by Dedieu and Shub, both
concerning Lyapunov exponents. Indeed, we show that equality holds
in Herman's result.