A median of a sequence pi = x1, x2, … , xk of elements of a finite metric space (X, d ) is an element x for which ∑ k, i=1 d(x, xi) is minimum. The function M with domain the set of all finite sequences on X and defined by M(pi) = {x: x is a median of pi} is called the median function on X,...

A median of a sequence ï° = x1, x2, … , xk of elements of a finite metric space (X, d ) is an element x for which  1 ≤ I ≤ k d(x, xi) is minimum. The function M with domain the set of all finite sequences on X and defined by M(ï°) = {x: x is a median of ï°} is...