  The performance of iterative decoding techniques for linear block codes
correcting erasures depends very much on the sizes of the stopping sets
associated with the underlying Tanner graph, or, equivalently, the parity-check
matrix representing the code. In this paper, we introduce the notion of
dead-end sets to explicitly demonstrate this dependency. The choice of the
parity-check matrix entails a trade-off between performance and complexity. We
give bounds on the complexity of iterative decoders achieving optimal
performance in terms of the sizes of the underlying parity-check matrices.
Further, we fully characterize codes for which the optimal stopping set
enumerator equals the weight enumerator.
