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This example shows a vector , x , with 0 stride and a vector , z , with negative stride . Make up a new version of A by adding to a copy of it a new terminal node z , with unlabeled transitions to it from each accepting state in A. This example shows a vector , x , with 0 stride , and a vector , z , with negative stride . We present a perfect simulation algorithm for stationary processes indexed by Z , with summable memory decay .