A note on t-unidirectional error correcting and d(d>or=t)-unidirectional error detecting (t-UEC and d-UED) codes

Necessary and sufficient conditions for t-unidirectional error correcting and d-unidirectional error detecting (t-UEC and d-UED) codes are shown. In addition, an error in a theorem previously published on t-UEC and d-UED codes (see D.J. Lin and B. Bose, IEEE Trans. Comput., vol.37, p.433-39, Apr. 1988) is corrected.<
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