@conference {34, title = {Symmetries in Modal Logics: A Coinductive Approach}, booktitle = {Proceedings of the 7th Workshop on Logical and Semantic Frameworks, with Applications (LSFA 2012)}, year = {2012}, month = {September}, address = {Rio de Janeiro}, abstract = {We generalize the notion of symmetries of propositional formulas in conjunctive normal form to modal formulas. Our framework uses the coinductive models introduced in [4] and, hence, the results apply to a wide class of modal logics including, for example, hybrid logics. Our main result shows that the symmetries of a modal formula preserve entailment: if \sigma is a symmetry of \phi then \phi |= \psi if and only if \phi |= \sigma(\psi).}, author = {Carlos Areces and Hoffmann, G. and Ezequiel Orbe} }