Lance Fortnow William I. Gasarch Sanjay Jain Efim B. Kinber Martin Kummer Stuart A. Kurtz Mark Pleszkovich Theodore A. Slaman Robert Solovay Frank Stephan Extremes in the Degrees of Inferability. 231-276 1994 66 Ann. Pure Appl. Logic 3 db/journals/apal/apal66.html#FortnowGJKKKPSSS94 http://dx.doi.org/10.1016/0168-0072(94)90035-3