@article {icl:545, title = {Sparse approximations of the Schur complement for parallel algebraic hybrid solvers in 3D}, journal = {Numerical Mathematics: Theory, Methods and Applications}, volume = {3}, number = {3}, year = {2010}, month = {2010-00}, pages = {64-82}, publisher = {Golbal Science Press}, address = {Beijing}, author = {Luc Giraud and Azzam Haidar and Yousef Saad}, editor = {C. Zhiming} }