Iterated Function Systems of Generalized Finite Type

For iterated function systems (IFS) of contractive similitudes on R ^d , we introduce a generalized finite type condition which allows us to include some IFS's of contractive similitudes with overlaps whose contraction ratios are not exponentially commensurable. We show that this condition extends the finite type condition and the open set condition. It also implies the weak separation property. We also show that under this condition, the Hausdorff dimension of the attractor can be computed in terms of the spectral radius of a weighted incidence matrix.