Weak insensitivity to initial conditions at the edge of chaos in the   logistic map
  We extend existing studies of weakly sensitive points within the framework of Tsallis non-extensive thermodynamics to include weakly insensitive points at the edge of chaos. Analyzing tangent points of the logistic map we have verified that the generalized entropy with suitable entropic index q correctly describes the approach to the attractor. 
M. Coraddu, F. Meloni, G. Mezzorani, R. Tonelli