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A generalized automaton (GA) is a nite automaton where the single transitions are deened on words rather than on single letters. Generalized automata were considered by K. Hashiguchi who proved that the problem of calculating the size of a minimal GA is decidable. We deene the model of deterministic generalized automaton (DGA) and study the problem of its(More)
We investigate the complexity of a variety of normal-form transformations for extended context-free grammars, where by extended we mean that the set of right-hand sides for each nonterminal in such a grammar is a regular set. The study is motivated by the implementation project GraMa which will provide a C++ toolkit for the symbolic manipulation of(More)
Tiling systems that recognize two-dimensional languages are intrinsically non-deterministic models. We introduce the notion of deter-ministic tiling system that generalizes deterministic automata for strings. The corresponding family of languages matches all the requirements of a robust deterministic class. Furthermore we show that, differently from the(More)
We consider non-self-embedding (NSE) context-free grammars as a representation of regular sets.We point out its advantages with respect to more classical representations by finite automata, in particular when considering the efficient realization of the rational operations. We give a characterization in terms of composition of regular grammars and state(More)