Monday, 13 April 2009

ds.dynamical systems - Partitions and Expansiveness

Why if one have an varepsilon-expansive homeomorphism T:XrightarrowX (X a compact metric space) and a given partition D of X which has diameter smaller than varepsilon the sequence of refined partitions Dn=bigveeni=nTiD has diameter converging to zero ?



Recall that a varepsilon-expansive homeomorphism T is such that given any two distinct points x and y there exist ninmathbfZ such that d(Tnx,Tny)>varepsilon



I can see intituively why this is true, somehow the refined partitions have less an less points in its members precisely because they have diameter less than epsilon but T keeps separating points (and i fact open sets of points) at distance greater than varepsilon.



Thanks in advance!

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