Directed Simulations
نویسندگان
چکیده
Although negation-free languages are widely used in logic and computer science, relatively little is known about their expressive power. To address this issue we consider a kind of non-symmetric bisimuIations called directed simulations, and use these to analyze the expressive power and model theory of negation-free modal and temporal languages. We first use them to obtain preservation, safety and definability results for a simple negation-free modal language. We then obtain analogous results for stronger negation-free languages. Finally, we extend our methods to deal with languages with non-boolean negation.
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