A Lower Bound Technique for Communication on BSP with Application to the FFT

Communication complexity is defined, within the Bulk Synchronous Parallel (BSP) model of computation, as the sum of the degrees of all the supersteps. A lower bound to the communication complexity is derived for a given class of DAG computations in terms of the switching potential of a DAG, that is, the number of permutations that the DAG can realize when viewed as a switching network. The proposed technique yields a novel and tight lower bound for the FFT grap