In mathematics, the Grothendieck inequality states that there is a universal constant with the following property. If Mij is an n by n (real or complex) matrix with for all (real or complex) numbers si, tj of absolute value at most 1, then , The Grothendieck inequality and Grothendieck constants are named after Alexander Grothendieck, who proved the existence of the constants in a paper published in 1953.