  Discretizations of infinite-dimensional variational inequalities lead to
linear and nonlinear complementarity problems with many degrees of freedom. To
solve these problems in a parallel computing environment, we propose two
active-set methods that solve only one linear system of equations per
iteration. The linear solver, preconditioner, and matrix structures can be
chosen by the user for a particular application to achieve high parallel
performance. The parallel scalability of these methods is demonstrated for some
discretizations of infinite-dimensional variational inequalities.
