Linear complementarity on simplicial cones and the congruence orbit of   matrices
  The congruence orbit of a matrix has a natural connection with the linear complementarity problem on simplicial cones formulated for the matrix. In terms of the two approaches -- the congruence orbit and the family of all simplicial cones -- we give equivalent classification of matrices from the point of view of the complementarity theory. 
A. B. N\'emeth and S. Z. N\'emeth
math.OC