Lebesgue Sets of Izobov Exponents of Linear Differential Systems. I.

We give a complete description of the Lebesgue sets of upper Izobov -exponents of linear differential systems continuously depending on a parameter varying in a metric space. We prove the simultaneous attainability of the upper Izobov -exponents by the Lyapunov exponents and their upper semicontinuity as functions of the perturbation exponent . [ABSTRACT FROM AUTHOR]