 Kummer, M. 

 Cholak, P.  Degrees of inferability  1992 
 Kummer, M.  The strength of noninclusions for teams of finite learners  1994 
 Fortnow, L.  Extremes in the Degrees of Inferability  1994 
 Kummer, M.  Inclusion problems in parallel learning and games  1994 
