Conditions are given for uniqueness of solutions of linear time-invariant s
ystems under relay feedback. From a hybrid dynamical point of view this ent
ails the deterministic specification of the discrete transition rules. The
results are based on the formulation of relay systems as complementarity sy
stems, and use the constructive theory of the Linear Complementarity Proble
m. (C) 1999 Elsevier Science Ltd. All rights reserved.