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 prove that Szilard languages of context-free grammars can be accepted by an indexing alternating Turing machine (indexing ATM) in logarithmic time and space. The same result holds for leftmost Szilard languages of unrestricted (phrase-structure or type 0) grammars. Since the class of languages recognizable by an indexing ATM in logarithmic time equals(More)
The paper presents an original survey on Web ontology editing tools, in respect with Semantic Web actual technologies. The material is focused on features that these tools might expose: granularity of expressivity, Web standards compliance, reasoning support, provided APIs and, not least, the interoperability issues. The comparative study is used a specific(More)
This paper concerns linear context-free languages (LIN). We prove that LIN ⊆ NC (under UE∗−uniformity reduction). We introduce a new normal form for context-free grammars, called Dyck normal form. Using this new normal form we prove that for each context-free language L there exist an integer K and a homomorphism φ such that L = φ(D′ K), where D′ K ⊆ DK ,(More)
We investigate computational resources used by alternating Turing machines (ATMs) to accept Szilard languages (SZLs) of context-free matrix grammars (MGs). The main goal is to relate these languages to parallel complexity classes such as NC1 and NC2. We prove that unrestricted and leftmost-1 SZLs of context-free MGs, without appearance checking, can be(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 nonterminals 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)