Anomalous sensitivity to initial conditions and entropy production in   standard maps: Nonextensive approach
  We perform a throughout numerical study of the average sensitivity to initial conditions and entropy production for two symplectically coupled standard maps focusing on the control-parameter region close to regularity. Although the system is ultimately strongly chaotic (positive Lyapunov exponents), it first stays lengthily in weak-chaotic regions (zero Lyapunov exponents). We argue that the nonextensive generalization of the classical formalism is an adequate tool in order to get nontrivial information about this complex phenomenon. Within this context we analyze the relation between the power-law sensitivity to initial conditions and the entropy production. 
Garin F.J. Ananos, Fulvio Baldovin, Constantino Tsallis