Liliana Cojocaru

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<i>Watson-Crick Automata</i> are a counterpart of finite automata working on a <i>Watson-Crick tape</i> composed of double stran-ded sequences of symbols linked by a complementarity relation like DNA molecules. Consequently, these devices have as input double strands of strings of symbols arranged in a pairwise affinity similar to Watson-Crick(More)
We introduce a normal form for context-free grammars, called Dyck normal form. This is a syntactical restriction of the Chomsky normal form, in which the two nonter-minals occurring on the right-hand side of a rule are paired nonterminals. This pairwise property allows to define a homomorphism from Dyck words to words generated by a grammar in Dyck normal(More)
We investigate computational resources used by alternating Turing machines (ATMs) to accept Szilard languages (SZLs) of regulated rewriting grammars. The main goal is to relate these languages to low-level complexity classes such as N C 1 and N C 2. We focus on the derivation process in random context grammars (RCGs) with context-free rules. We prove that(More)