A topological horseshoe in the hyperchaotic Rössler attractor

This Letter reports a horseshoe with two-directional expansion in the 4D hyperchaotic Rössler system. In order to show that it is indeed a horseshoe with two-dimensional expansion, some simple results on topological horseshoe which are applicable to 3D hyperchaotic maps are presented. In this way, a computer-assisted verification of hyperchaoticity is presented.