"Compress and eliminate" solver for symmetric positive definite sparse   matrices
  We propose a new approximate factorization for solving linear systems with symmetric positive definite sparse matrices. In a nutshell the algorithm is to apply hierarchically block Gaussian elimination and additionally compress the fill-in. The systems that have efficient compression of the fill-in mostly arise from discretization of partial differential equations. We show that the resulting factorization can be used as an efficient preconditioner and compare the proposed approach with state-of-art direct and iterative solvers. 
Daria A. Sushnikova and Ivan V. Oseledets
math.NA cs.NA