A Lower Bound on the Expected Length of 1-1 Codes
نویسندگان
چکیده
We show that the minimum expected length of a 1-1 encoding of a discrete random variable X is at least H(X)− log(H(X)+1)− log e and that this bound is asymptotically achievable.
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امید ریاضی نرخ پوشش برای ماتریسهای هلمن
Hellman’s time-memory trade-off is a probabilistic method for inverting one-way functions, using pre-computed data. Hellman introduced this method in 1980 and obtained a lower bound for the success probability of his algorithm. After that, all further analyses of researchers are based on this lower bound. In this paper, we first studied the expected coverage rate (ECR) of the Hellman matrice...
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