 The Gleason – Prange theorem is named after Gleason 's work with <unk> researcher Eugene Prange ; it was originally published in a 1964 <unk> research report by H. F. Mattson , Jr. and E. F. <unk> , 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 <unk> ( n ) as a subgroup of its symmetries . 
