Theorem. Suppose the open set condition holds and each ψ<sub>i</sub> is a similitude, that is a composition of an isometry and a dilation around some point. Then the unique fixed point of ψ is a set whose Hausdorff dimension is s where s is the unique solution of | Theorem. Suppose the open set condition holds and each ψ<sub>i</sub> is a similitude, that is a composition of an isometry and a dilation around some point. Then the unique fixed point of ψ is a set whose Hausdorff dimension is s where s is the unique solution of |