Invariant subspaces of contractions with constant characteristic function.

We describe all the invariant subspaces of a completely nonunitary contraction T_c with nonzero scalar constant characteristic function c, where |c|<1. Moreover, we show that T_c and restriction to its invariant subspaces are essentially normal. Using this description of T_c-invariant subspaces, we then identify the hyperinvariant subspaces. [ABSTRACT FROM AUTHOR]