  In this work, with the help of fractional calculus, it is shown a time
dependence of entropy more general than the well known Pesin relation is
derived. Here the equiprobability postulate is not assumed, the system dynamic
in the phase space is not necessarily Markovian and the system is not in a
steady state at all. Different possibilities for the time evolution of entropy
by considering different features of the phase space and processes involved are
obtained.
