“…We have now access to a systematic treatment of modal logics in display calculus [32], calculus of structures [26,14], labeled systems [25,22], hyper sequents [3,18], and nested sequents [5,28,20]. There are focused proof systems for classical and intuitionistic modal logics [7,8], and we understand the relation between display calculus and nested sequents [10] and hyper sequents [11].…”