Classical cryptosystems of the type " Richeheu " or " garbage-in-between " give rise to ideas and notions so far neglected in the theory of formal languages. This paper investigates such notions, mainly from the point of view of decidability.
The measure of the influence of an observation on a statistical estimator is the φ-divergence. We present a comparative computational study of the estimators of the φ-divergence, Monte-Carlo and bootstrap estimators, used for detection of the outliers data. We also give estimators for the prediction density of the Random Coefficient Autoregressive (RCA)… (More)
A classical cryptosystem and a public-key cryptosystem are proposed, based on the passing from a string of production labels (embedding in some way the message to be encrypted) to the string generated by the grammar by a (leftmost) derivation with that given control word (thus obtaining the cyphertext). Some problems of formal language theory appearing in… (More)