= Relatively almost periodic observable
{title2=$\min_j\|U_T^nf-g_j\|_y<\varepsilon$}
= Relative almost periodicity
{synonym}
= Relatively almost periodic
{synonym}
For every positive $\varepsilon$, require finitely many global $L^2$ centers $g_j$ such that the displayed inequality holds for every integer $n$ on almost every fiber of the <factor map>. A center can depend on the fiber and time; its finite list is fixed. This is weaker than <almost periodic observable> in global norm. For noninvertible systems use nonnegative times.
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