Escape from strange repellers

In a dynamical system described by a map, it may be that a “strange” sets of points is left invariant under the mapping. The set is a repeller if points placed in its neighborhood move away. An escape rate is defined to describe this motion. An alternative method of evaluating the escape rate, based on the consideration of repulsive cycles, is proposed. In the several cases examined numerically and analytically, the escape rate is shown to agree with the proposed formula.