Combinatorial Dynamics And Entropy In Dimension OneIn last thirty years an explosion of interest in the study of nonlinear dynamical systems occured. The theory of one dimensional dynamical systems has grown out in many directions. One of them has its roots in the Sharkovski0 Theorem. This beautiful theorem describes the possible sets of periods of all cycles of maps of an interval into itself. Another direction has its main objective in measuring the complexity of a system, or the amount of chaos