Experts in information theory have long been interested in the maximal size A(n, d) of a binary error-correcting code of length n and distance d, The problem of determining A(n, d) involves both the construction of good codes and the search for good upper bounds. From 1973 to 2003, the linear programming bound found many applications, but there were few significant theoretical advances until Schrijver proposed a new code upper bound via semidefinite...