On signed graphs and gramians

Let A be a symmetric matrix with entries (0, 1, -1) and ¹(A) its smallest eigenvalue. We consider the question of how closely A–¹(A)I can be approximated by a gramian KK^T, where each entry in K is 0, 1, or -1.This work was supported (in part) by the U.S. Army Research Office under Contract DAAG 29-74-C-0007.