Pierre Collet, Servet Martinez, Veronique Maume-Deschamps
Conditionally Invariant Probability Measures in Dynamical Systems.
(133K, ps file)

ABSTRACT.  Let $T$ be a measurable map on a Polish space $X$, 
let $Y$ be a non trivial subset of $X$. We give 
conditions ensuring existence of conditionally 
invariant probability measures (to non absorption in $Y$). 
We also supply sufficient conditions for these probability 
measures to be absolutely continuous with respect to some regular 
measure.