 Andrew Mattei Gleason ( November 4 , 1921 – October 17 , 2008 ) was an American mathematician who as a young World War II naval officer broke German and Japanese military codes , then over the succeeding sixty years made fundamental contributions to widely varied areas of mathematics , including the solution of Hilbert 's fifth problem , and was a leader in reform and innovation in math ­ e ­ mat ­ ics teaching at all levels . Gleason 's theorem in quantum logic and the Greenwood – Gleason graph , an important example in Ramsey theory , are named for him . 
