Convergence of subdivision schemes associated with nonnegative masks

This paper is concerned with refinement equations of the type [GRAPHICS] where f is the unknown function defined on the s-dimensional Euclidean spac e R-s, a is a finitely supported sequence on Z(s), and M is an s x s dilati on matrix with m := \det M\. The solution of a refinement equation can be o btained by using the subdivision scheme associated with the mask. In this p aper we give a characterization for the convergence of the subdivision sche me when the mask is nonnegative. Our method is to relate the problem of con vergence to m column-stochastic matrices induced by the mask. In this way, the convergence of the subdivision scheme can be determined in a finite num ber of steps by checking whether each finite product of those column-stocha stic matrices has a positive row. As a consequence of our characterization, we show that the convergence of the subdivision scheme with a nonnegative mask depends only on the location of its positive coefficients. Several exa mples are provided to demonstrate the power and applicability of our approa ch.