Stephen G. Simpson. Degrees of Unsolvability: A Tutorial. In Arnold Beckmann, Victor Mitrana, Mariya Ivanova Soskova, editors, Evolving Computability - 11th Conference on Computability in Europe, CiE 2015, Bucharest, Romania, June 29 - July 3, 2015. Proceedings. Volume 9136 of Lecture Notes in Computer Science, pages 83-94, Springer, 2015. [doi]
Abstract is missing.