The Complementary Problem

Problems of the form

F(x) >=0
x >=0
F_i(x) x_i>=0, i=1,...,n . If F depends linearly on x, then we have a linear, otherwise a nonlinear complementarity problem. Problems of this type occur often e.g. in mechanics, finance and games. Linear complementarity problems typically are solved by so called principal pivoting algorithms and nonlinear ones by a nonsmooth nonlinear equations approach using appropriate variants of the damped Newton's method e.g.
H(x)=0
with H_i(x)=SQRT( F_i² (x)+x_i²)-F_i (x)- x_i
Systems of equations, various pieces of software, mostly in Matlab, documentation, testproblems, net-submission and other info see:

	CPNet/software
	AMPL interface to PATH

For more information on complementarity problems see CPNET which provides a directory of researchers, related software, overview on applications, an own archive, calendar of related events (meetings) and relevant web sites.