In mathematics, the Johnson scheme, named after Selmer M. Johnson, is also known as the triangular association scheme. It consists of the set of all binary vectors X of length ℓ and weightn. Two vectorsx,yX are called ith associates if dist(x,y)=2i for i=0,1,...,n. The eigenvalues are given by

where

and Ek(x) is an Eberlein polynomial defined by

References