A method includes associating, in a graph including graph nodes connected via of edges, a respective node weight with each of the graph nodes, and organizing the graph nodes into ancestor nodes, each of the ancestor nodes having one or more descendent nodes so that the ancestor and the descendent nodes include all the graph nodes. For a given descendent node, a respective path to one or more of the ancestor nodes is identified, each of the respective paths including one or more edges, and a given ancestor node having a shortest of the identified paths is determined. A respective edge weight is assigned to each of the one or more edges in the shortest path, and, for the given descendent node, a node loss value is calculated based on the node weight and the respective edge weight of the each of the one or more edges.