Bernd Borchert, Dietrich Kuske, Frank Stephan. On Existentially First-Order Definable Languages and Their Relation to NP. In Kim Guldstrand Larsen, Sven Skyum, Glynn Winskel, editors, Automata, Languages and Programming, 25th International Colloquium, ICALP 98, Aalborg, Denmark, July 13-17, 1998, Proceedings. Volume 1443 of Lecture Notes in Computer Science, pages 17-28, Springer, 1998. [doi]
Abstract is missing.