ALGEBRAIC MULTIGRID BY SMOOTHED AGGREGATION FOR SECOND AND FOURTH ORDER ELLIPTIC PROBLEMS Petr Vanek, Jan Mandel, and Marian Brezina Abstract An algebraic multigrid algorithm is developed based on prolongations by smoothed aggregation. Coarse levels are generated automatically. Guidelines for the selection of method components are presented based on energy considerations. Efficiency of the resulting algorithm is demonstrated by computational results.