Optimal varying dyadic structure models of time invariant systems

The problem of approximation of a time-invariant system by a varying dyadic structure model is considered. The increase in network implementation complexity of varying structure systems is avoided by considering dyadic groups only. The problem of best approximation in Euclidean norm is solved, and it is shown that, in general, there does not exist a one-to-one correspondence between causal and symmetric linear systems and their best models.<<ETX>>