Below is the ascii version of the abstract for 98-717. The html version should be ready soon.

Correlations decay for Markov maps on a countable states space.
(305K, compressed postscript file)

ABSTRACT.  We estimate the decay of correlations for some Markov maps on a 
countable states space. A necessary and sufficient condition is given 
for the transfer operator to be quasi-compact on the space of locally 
Lipschitz functions. In the non quasi-compact case, the decay of correlations depends on the contribution to the 
transfer operator of the complementary of finitely many 
cylinders. Estimates are given for some non uniformly expanding maps 
and for birth-and-death processes.