Philipp Weis, Neil Immerman. Structure Theorem and Strict Alternation Hierarchy for FO:::2::: on Words. In Jacques Duparc, Thomas A. Henzinger, editors, Computer Science Logic, 21st International Workshop, CSL 2007, 16th Annual Conference of the EACSL, Lausanne, Switzerland, September 11-15, 2007, Proceedings. Volume 4646 of Lecture Notes in Computer Science, pages 343-357, Springer, 2007. [doi]
Abstract is missing.