“…For problems related to variational inequalities, there are results by Lions [14], Hoffman and Zou [8], Kuznetsov and Neittaanmäki [10], Kuznetsov, Neittaanmäki and Tarvainen [11]- [12], Lü, Liem and Shih [18], Tarvainen [19], Badea [2], and Zeng and Zhou [20] in the domain decomposition method, and by Kornhuber [9] and Mandel [13] in the multigrid method. Despite those results, the functioning and convergence of the Schwarz domain decomposition method is not fully understood for variational inequalities.…”