  In this paper, we show that, under some technical assumptions, the
Kolmogorov-Sinai entropy and the permutation entropy are equal for
one-dimensional maps if there exists a countable partition of the domain of
definition into intervals such that the considered map is monotone on each of
those intervals. This is a generalization of a result by Bandt, Pompe and G.
Keller, who showed that the above holds true under the additional assumptions
that the number of intervals on which the map is monotone is finite and that
the map is continuous on each of those intervals.
