Alexander V. Chagrov, Mikhail N. Rybakov. How Many Variables Does One Need to Prove PSPACE-hardness of Modal Logics. In Philippe Balbiani, Nobu-Yuki Suzuki, Frank Wolter, Michael Zakharyaschev, editors, Advances in Modal Logic 4, papers from the fourth conference on Advances in Modal logic, held in Toulouse (France) in October 2002. pages 71-82, King s College Publications, 2002.
Abstract is missing.