Languages with homomorphic replacements

A Homomorphic Representation of Simple Matrix Languages

In this paper we continue the investigation of simple matrix languages introduced by Ibarra (1970) as a subfamily of matrix languages. Simple matrix languages have many properties similar to those of context-free languages. In the following, we prove that every simple matrix language can be written as a homomorphic image of the intersection of the Dyck context-free language and an equal matrix ...

On Subword Complexities of Homomorphic Images of Languages

— The subword complexity of a language K is the function nK on positive integer s such that nK (n) equals the number of different subwords of length n appearing in words of X. We investigate the relationship between nk(K) and nK where Kis a language and h is a homorphism. This study is aiso carried out for the special case when Kis a DOL language. Resumé. — La complexité des facteurs d'un langa...

Homomorphic Encryption with CCA Security

We address the problem of constructing public-key encryption schemes that meaningfullycombine useful computability features with non-malleability. In particular, we investigate schemesin which anyone can change an encryption of an unknown message m into an encryption of T (m)(as a feature), for a specific set of allowed functions T , but the scheme is “non-malleable” withrespect...

Molecular replacements

Homomorphic Images of Sentential Form Languages Defined by Semi-Thue Systems

We investigate various language famili$:s which can be obtained from sentential form languages of semi-Thue systems by applying codmgs, weak codings, non-erasing homomorphisms, and arbitrary homomorphi5rns. We also distinguish between monotone, contexi-independent, and context-dependent semi-Thur systems with at most one or finitely many starting words. Finally, we study the effect of erasing p...