Agi Kurucz, Frank Wolter, Michael Zakharyaschev. Islands of Tractability for Relational Constraints: Towards Dichotomy Results for the Description Logic EL. In Lev D. Beklemishev, Valentin Goranko, Valentin Shehtman, editors, Advances in Modal Logic 8, papers from the eighth conference on "Advances in Modal Logic," held in Moscow, Russia, 24-27 August 2010. pages 271-291, College Publications, 2010. [doi]
Abstract is missing.