 The Gleason – Prange theorem is named after Gleason 's work with AFCRL researcher Eugene Prange ; it was originally published in a 1964 AFCRL research report by H. F. Mattson , Jr. and E. F. Assmus , Jr . It concerns the quadratic residue code of order n , extended by adding a single parity check bit . This " remarkable theorem " shows that this code is highly symmetric , having the projective linear group PSL2 ( n ) as a subgroup of its symmetries . 
