|Dept.||Univ. Paris 7 (Diderot)|
We first recall that normality can be characterized by incompressibility by finite state machines. We show that this characterization is robust as it does not depend on the variant of finite machines considered.
We consider the preservation of normality by selection based of prefixes and suffixes. We present a notion of independence based on incompressibilty for normal sequences. This independence can, in turn, be characterized by preservation of normality in several contexts.