<html><head><meta http-equiv="Content-Type" content="text/html; charset=us-ascii"></head><body style="word-wrap: break-word; -webkit-nbsp-mode: space; line-break: after-white-space;" class=""><div class="">We are looking for a PhD candidate for a research project Derivation Systems for Modal Fixpoint Logics.</div><div class=""><br class=""></div><div class="">Many applications of modal logic, in particular in computer science, require the formalism to deal with various kinds of recursion. Modal fixpoint logics are extensions of basic modal logic that deal with the concept of recursion in an elegant and fundamental way by adding operators or connectives that can express</div><div class="">recursive statements. Whereas semantic and computational aspects of these logics are by now reasonably well understood, the theory of proof systems for modal fixpoint logics has remained relatively underdeveloped.</div><div class=""><br class=""></div><div class="">The aim of the Derivation Systems for Modal Fixpoint Logics project is to develop a general and uniform theory of proof systems for modal fixpoint logics. Such a</div><div class="">theory will extend that of basic modal logics with proof systems that allow fo derivations that are circular or feature other mechanisms for dealing with the recursive nature of fixpoints. The envisaged methodology for designing and studying such proof systems will integrate insights from proof theory with ideas from the theories of automata, infinite games, and (co-)algebra.</div><div class=""><br class=""></div><div class="">The research project Derivation Systems for Modal Fixpoint Logics was awarded to Prof.Dr. Yde Venema by the Netherlands Organisation for Scientific Research (NWO) in the ENW TOP grant programme. It is part of a larger project on proof systems for modal fixpoint logics, directed by Venema together with Dr. Bahareh Afshari.</div><div class=""><br class=""></div><div class="">For more details and information on the application procedure, see</div><div class=""><br class=""></div><div class=""><a href="https://www.illc.uva.nl/NewsandEvents/News/Positions/newsitem/12740/PhD-in-Proof-Systems-for-Modal-Fixpoint-Logics" class="">https://www.illc.uva.nl/NewsandEvents/News/Positions/newsitem/12740/PhD-in-Proof-Systems-for-Modal-Fixpoint-Logics</a></div><div class=""><br class=""></div><div class="">or contact Yde Venema at <a href="mailto:y.venema@uva.nl" class="">y.venema@uva.nl</a>, or Bahareh Afshari at <a href="mailto:b.afshari@uva.nl" class="">b.afshari@uva.nl</a>.</div><div class=""><br class=""></div><div class="">The deadline for applications is Monday 7 June; the preferred starting date is 1 September 2021.</div></body></html>