A Sequent Calculus for a Modal Logic on Finite Data Trees

International audienceWe investigate the proof theory of a modal fragment of XPath equipped with data (in)equality tests over finite data trees, i.e. over finite unranked trees where nodes are labelled with both a symbol from a finite alphabet and a single data value from an infinite domain. We present a sound and complete sequent calculus for this logic, which yields the optimal PSPACE complexity bound for its validity problem