Copy and remove as dynamic operators

Abstract

In this article, we present a modal logic that extends the basic modal logic with two dynamic operators: copy (), which replicates the current model, labelling each copy with a different propositional symbol and respecting accessibility relations even between distinct copies; and remove (), which deletes paths in the model that satisfy certain intermediate conditions. We call the resulting logic . We study its computational complexity, and its relative expressivity with respect to (static) modal logics and , and the dynamic epistemic Action Model Logic, .