Dora Giammarresi

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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 deterministic 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)
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)