title: Required criteria for recognizing new types of chaos: application to the "cord" attractor.
abstract: After suggesting criteria to recognize a new system and a new attractor-and to make a distinction between them-the paper details the topological analysis of the "cord" attractor. This attractor, which resembles a cord between two leaves, is produced by a three-dimensional system that is obtained after a modification of the Lorenz-84 model for the global atmospheric circulation [L. A. Aguirre and C. Letellier, Phys. Rev. E 83, 066209 (2011)]. The nontrivial topology of the attractor is described in terms of a template that corresponds to a reverse horseshoe, that is, to a spiral Rössler attractor with negative and positive global π twists. Due to its particular structure and to the fact that such a system has two variables from which the dynamics is poorly observable, this attractor qualifies as a challenging benchmark in nonlinear dynamics.
authors.affiliation: CORIA UMR 6614, Université de Rouen, Avenue de l'Université, BP 12, F-76801 Saint-Etienne du Rouvray cedex, France.
authors.forename: Christophe
authors.initials: C
authors.lastname: Letellier
authors.forename: Luis A
authors.initials: LA
authors.lastname: Aguirre