  In this paper, the duality of erasures and defects will be investigated by
comparing the binary erasure channel (BEC) and the binary defect channel (BDC).
The duality holds for channel capacities, capacity achieving schemes, minimum
distances, and upper bounds on the probability of failure to retrieve the
original message. Also, the binary defect and erasure channel (BDEC) will be
introduced by combining the properties of the BEC and the BDC. It will be shown
that the capacity of the BDEC can be achieved by the coding scheme that
combines the encoding for the defects and the decoding for the erasures. This
coding scheme for the BDEC has two separate redundancy parts for correcting
erasures and masking defects. Thus, we will investigate the problem of
redundancy allocation between these two parts.
