The system presented, LEFT, learns most specific generalizations (MSGs)from structural descriptions. The new inductive multistaged generalization algorithm is based on several new or enhanced ideas that improve the quality of generalization using weighted predicates and make it applicable to real world problems. The algorithm distinguishes between important and less important predicates. Built-in predicates are used to select alternative MSGs and improve the resulting hypothesis. The system has been applied successfully to chip-floorplanning, a subtask of VLSI design. It acquires rules describing single floorplanning steps.