Dynamics of sub-hyperbolic and semi-hyperbolic rational semigroups and skew products

We consider dynamics of sub-hyperbolic and semi-hyperbolic semigroups of ra tional functions on the Riemann sphere and will show some no wandering doma in theorems. The Julia set of a rational semigroup in general may have non- empty interior points. We give a sufficient condition that the Julia set ha s no interior points. From some information about forward and backward dyna mics of the semigroup, we consider when the area of the Julia set is equal to zero or an upper estimate of the Hausdorff dimension of the Julia set.