# Taming the `elsewhere': On expressivity of topological languages

@inproceedings{FernandezDuque2021TamingT, title={Taming the `elsewhere': On expressivity of topological languages}, author={David Fern'andez-Duque}, year={2021} }

In topological modal logic, it is well known that the Cantor derivative is more expressive than the topological closure, and the ‘elsewhere,’ or ‘difference,’ operator is more expressive than the ‘somewhere’ operator. In 2014, Kudinov and Shehtman asked whether the combination of closure and elsewhere becomes strictly more expressive when adding the Cantor derivative. In this paper we give an affirmative answer: in fact, the Cantor derivative alone can define properties of topological spaces…

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